Malware Analysis Report (AR21-202F)

MAR-10334587-2.v1: Pulse Connect Secure

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Summary

Malware Analysis Report
10334587.r2.v1
2021-07-14

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.cisa.gov/tlp.

Summary

Description

CISA received one file for analysis. The file is a modified Pulse Secure Perl Common Gateway Interface (CGI) script. The modified script functions as a webshell that hijacks two legitimate inputs. This analysis is derived from malicious files found on Pulse Connect Secure devices.

For a downloadable copy of IOCs, see: MAR-10334587-2.v1.WHITE.stix.

Submitted Files (1)

0460f9c22127055b337d2b67ee782e7454dc13e7993430020e62518654cb045b (tnchcupdate.cgi)

Findings

0460f9c22127055b337d2b67ee782e7454dc13e7993430020e62518654cb045b

Tags

webshell

Details
Name tnchcupdate.cgi
Size 29056 bytes
Type Perl script text executable
MD5 92dfab44b0777f1b0da83c3c4cca4d56
SHA1 04a5d3d01ca5083d8adbae2b84794f0bf506d51f
SHA256 0460f9c22127055b337d2b67ee782e7454dc13e7993430020e62518654cb045b
SHA512 835c897c7b8c810543f589ed9a0421b1845d43192949cdc3831e0eee112fc26dbcbab1520254f56930c6fbf00365911ab1084059846a213faee5f13e30f9d7c5
ssdeep 384:DSVXaipozdVFIMIVzjJVreteR03LD/AxrYjVmzp3LulFNF2K9gjOw:DSVXaiMdn4jJVrete2gxrYj4Wn2K2D
Entropy 4.976907
Antivirus

No matches found.

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This is a modified Pulse Secure Perl CGI script that functions as a webshell. It is used to hijack two legitimate inputs 'hmacTime' and 'deviceid' and allows the attacker to activate and run remote commands.

The main function contains malicious code that accepts the attacker's inputs via parameter 'hmacTime' and parameter 'deviceid'.

The input parameter 'hmacTime' from the attacker is RC4 encrypted and base64 encoded.

The 'deviceid' is compared with a hard-coded value that works as an authorization key to access the webshell. If it matches, the input parameter 'hmacTime' will be base64 decoded and RC4 decrypted by the function checkTimeP with a hard-coded key.

The decrypted command will be executed in function checkUserTime using popen. The output of the command will be RC4 encrypted with a hard-coded key and base64 encoded in function checkTimeU.

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://us-cert.cisa.gov/forms/feedback/

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

July 21, 2021: Initial Version

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