Malware Analysis Report (AR18-221A)

MAR-10135536-17 – North Korean Trojan: KEYMARBLE

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This Malware Analysis Report (MAR) is the result of analytic efforts between Department of Homeland Security (DHS) and the Federal Bureau of Investigation (FBI). Working with U.S. Government partners, DHS and FBI identified Trojan malware variants used by the North Korean government. This malware variant has been identified as KEYMARBLE. The U.S. Government refers to malicious cyber activity by the North Korean government as HIDDEN COBRA. For more information on HIDDEN COBRA activity, visit

DHS and FBI are distributing this MAR to enable network defense and reduce exposure to North Korean government malicious cyber activity.

This MAR includes malware descriptions related to HIDDEN COBRA, suggested response actions and recommended mitigation techniques. Users or administrators should flag activity associated with the malware, report the activity to the DHS National Cybersecurity and Communications Integration Center (NCCIC) or the FBI Cyber Watch (CyWatch), and give the activity the highest priority for enhanced mitigation.

This malware report contains analysis of one 32-bit Windows executable file, identified as a Remote Access Trojan (RAT). This malware is capable of accessing device configuration data, downloading additional files, executing commands, modifying the registry, capturing screen shots, and exfiltrating data.

For a downloadable copy of IOCs, see:

Submitted Files (1)

e23900b00ffd67cd8dfa3283d9ced691566df6d63d1d46c95b22569b49011f09 (704d491c155aad996f16377a35732c...)

IPs (3)





Size126976 bytes
TypePE32 executable (GUI) Intel 80386, for MS Windows
ESETa variant of Win32/NukeSped.H trojan
EmsisoftTrojan.GenericKD.4837544 (B)
K7Trojan ( 0050e4401 )
Quick HealTrojan.IGENERIC
SymantecProcess timed out
Yara Rules
hidden_cobra_consolidated.yararule rsa_modulus { meta: Author="NCCIC trusted 3rd party" Incident="10135536" Date = "2018/04/19" category = "hidden_cobra" family = "n/a" description = "n/a" strings: $n = "bc9b75a31177587245305cd418b8df78652d1c03e9da0cfc910d6d38ee4191d40" condition: (uint16(0) == 0x5A4D and uint16(uint32(0x3c)) == 0x4550) and any of them }
ssdeep Matches

No matches found.

PE Metadata
Compile Date2017-04-12 11:16:04-04:00
Import Hashfc7dab4d20f23681313b91eba653aa21
PE Sections
MD5NameRaw SizeEntropy
Microsoft Visual C++ v6.0

This application is a malicious 32-bit Windows executable file, which functions as a RAT. When executed, it de-obfuscates its application programming interfaces (APIs) and using port 443, attempts to connect to the hard-coded IP addresses listed below. After connecting, the malware waits for further instructions.

--Begin hard-coded IP addresses--
--End hard-coded IP addresses--

Static analysis reveals that this RAT uses a customized XOR cryptographic algorithm displayed in Figure 1 to secure its data transfers and command-and-control (C2) sessions. It is designed to accept instructions from the remote server to perform the following functions:

--Begin functions--
Download and upload files
Execute secondary payloads
Execute shell commands
Terminate running processes
Delete files
Search files
Set file attributes
Create registry entries for storing data:(HKEY_CURRENT_USER\SOFTWARE\Microsoft\WABE\DataPath)
Collect device information from installed storage devices (disk free space and their type)
List running processes information
Capture screenshots
Collect and send information about the victim's system (operating system, CPU, MAC address, computer name, language settings, list of disk devices and their type, time elapsed since the system was started, and unique identifier of the victim's system)
--End functions--

Figure 1 - Screenshot of the cryptographic algorithms the malware used to secure its data transfers and C2 sessions.

Figure 1 - Screenshot of the cryptographic algorithms the malware used to secure its data transfers and C2 sessions.

  • 443 TCP

Domain Name: KRYPT.COM
Registry Domain ID: 4620809_DOMAIN_COM-VRSN
Registrar WHOIS Server:
Registrar URL:
Updated Date: 2016-02-25T03:39:29Z
Creation Date: 1998-05-04T04:00:00Z
Registry Expiry Date: 2024-05-03T04:00:00Z
Registrar:, LLC
Registrar IANA ID: 146
Registrar Abuse Contact Email:
Registrar Abuse Contact Phone: 480-624-2505
Domain Status: clientDeleteProhibited
Domain Status: clientRenewProhibited
Domain Status: clientTransferProhibited
Domain Status: clientUpdateProhibited
Name Server: NS1.CF.KRYPT.COM
Name Server: NS2.CF.KRYPT.COM
Name Server: NS3.CF.KRYPT.COM
DNSSEC: signedDelegation
DNSSEC DS Data: 2371 13 2 503AEB51F773BBCA00DB982C938895EF147DDC7D48A4E1E6FD0FE5BE7B98DA0D
URL of the ICANN Whois Inaccuracy Complaint Form:
Last update of whois database: 2018-06-28T02:39:11Z


  • 443 TCP

Domain Name: SERVPAC.COM
Registry Domain ID: 81803816_DOMAIN_COM-VRSN
Registrar WHOIS Server:
Registrar URL:
Updated Date: 2013-12-27T04:46:10Z
Creation Date: 2001-12-31T08:29:34Z
Registry Expiry Date: 2018-12-31T08:29:34Z
Registrar:, LLC
Registrar IANA ID: 146
Registrar Abuse Contact Email:
Registrar Abuse Contact Phone: 480-624-2505
Domain Status: clientDeleteProhibited
Domain Status: clientRenewProhibited
Domain Status: clientTransferProhibited
Domain Status: clientUpdateProhibited
Name Server: NS1.SERVPAC.COM
Name Server: NS2.SERVPAC.COM
DNSSEC: unsigned
URL of the ICANN Whois Inaccuracy Complaint Form:
Last update of whois database: 2018-06-28T02:40:41Z


  • 443 TCP

netnum: -
netname:        Nana10-LAN
descr:         Nana10-LAN
country:        IL
admin-c:        NV6695-RIPE
tech-c:         NV6695-RIPE
status:         ASSIGNED PA
mnt-by:         NV-MNT-RIPE
created:        2011-02-17T09:16:56Z
last-modified: 2011-02-17T09:16:57Z
source:         RIPE

person:         Nana 10 LTD
address:        1 Korazin str
address:        Givataim, Israel, 53583
mnt-by:         NV-MNT-RIPE
phone:         +972-73-7992000
fax-no:         +972-73-7992220
nic-hdl:        NV6695-RIPE
created:        2010-08-04T09:51:11Z
last-modified: 2011-02-17T09:01:21Z
source:         RIPE

% Information related to ''

descr:         013 Netvision Network
origin:         AS1680
mnt-by:         NV-MNT-RIPE
created:        1970-01-01T00:00:00Z
last-modified: 2009-03-26T10:55:12Z
source:         RIPE


Relationship Summary



NCCIC would like to remind users and administrators to 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 thumbdrives, external drives, CDs, etc.).
  • Scan all software downloaded from the Internet prior to executing.
  • Maintain situational awareness of the latest threats and implement appropriate ACLs.

Additional information on malware incident prevention and handling can be found in NIST's Special Publication 800-83, Guide to Malware Incident Prevention & Handling for Desktops and Laptops.

Contact Information

NCCIC 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:

Document FAQ

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 US-CERT and provide information regarding the level of desired analysis.

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

NCCIC 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 US-CERT's homepage at


August 9, 2018: Initial version

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