MAR-10334587-2.v1: Pulse Connect Secure

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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)

0460f9c22127055b337d2b67ee782e7454dc13e7993430020e62518654cb045b

Tags

webshell

Details

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.

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".

• 1-888-282-0870
• CISA Central (UNCLASS)
• CISA SIPR (SIPRNET)
• CISA IC (JWICS)

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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 Central.

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

• Web: https://malware.us-cert.gov
• E-Mail: submit@malware.us-cert.gov
• FTP: ftp.malware.us-cert.gov (anonymous)

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.