Trellix Insights: ChaChi GoLang RAT used in Ransomware Attacks
Technical Articles ID:
KB94919
Last Modified: 2022-09-07 09:28:09 Etc/GMT
Last Modified: 2022-09-07 09:28:09 Etc/GMT
Environment
IMPORTANT: This Knowledge Base article discusses a specific threat that is being automatically tracked by Trellix Insights technology. The content is intended for use by Trellix Insights users, but is provided for general knowledge to all customers. Contact us for more information about Trellix Insights.
Summary
The ChaChi remote access trojan (RAT) was used in multiple attacks against the government, healthcare, and educational sectors across the United States and the UK. The campaigns used obfuscation, cryptography, fallback channels, and proxies to stay under the radar. ChaChi uses components from open-source tools for DNS and HTTP tunneling to command-and-control servers. The RAT was used along with the PYSA/Mespinoza ransomware family for persistence and exfiltration.
Our Threat Research team gathers and analyzes information from multiple open and closed sources before disseminating intelligence reports. This campaign was researched by BlackBerry and shared publicly.
How to use this article:
- If a Threat Hunting table has been created, use the rules contained to search for malware related to this campaign.
- Review the product detection table and confirm that your environment is at least on the specified content version.
To download the latest content versions, go to the Security Updates page. - Scroll down and review the "Product Countermeasures" section of this article. Consider implementing them if they are not already in place.
- Review
KB91836 - Countermeasures for entry vector threats . - Review KB87843 - Dynamic Application Containment rules and best practices.
- Review KB82925 - Identify what rule corresponds to an Adaptive Threat Protection and Threat Intelligence Exchange event.
{ meta: description = "ChaChi RAT used in PYSA Ransomware Campaigns" author = "BlackBerry Threat Research & Intelligence" strings: // "Go build ID:" $go = { 47 6F 20 62 75 69 6C 64 20 49 44 3A } // dnsStream $dnsStream = { 64 6E 73 53 74 72 65 61 6D } // SOCKS5 $socks5 = { 53 4F 43 4B 53 35 } // chisel $chisel = { 63 68 69 73 65 6C } condition: // MZ signature at offset 0 uint16(0) == 0x5A4D and // PE signature at offset stored in MZ header at 0x3C uint32(uint32(0x3C)) == 0x00004550 and // ChaChi Strings all of them } |
This Knowledge Base article discusses a specific threat that's being tracked. The list of IOCs will change over time; check Trellix Insights for the latest IOCs.
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Minimum set of Manual Rules to improve protection to block this campaign:
IMPORTANT: Always follow best practices when you enable new rules and signatures.
When you implement new rules or signatures, always set them to Report mode first and check the alerts generated. Resolve any issues that arise and then set the rules to Block. This step mitigates against triggering false positives and allows you to refine your configuration.
For more information, see KB87843 - List of and best practices for Endpoint Security Dynamic Application Containment rules.
Endpoint Security - Advanced Threat Protection:
Endpoint Security - Exploit Prevention:
Aggressive set of Manual Rules to improve protection to block this campaign:
IMPORTANT: Always follow best practices when you enable new rules and signatures.
When you implement new rules or signatures, always set them to Report mode first and check the alerts generated. Resolve any issues that arise and then set the rules to Block. This step mitigates against triggering false positives and allows you to refine your configuration.
For more information, see KB87843 - List of and best practices for Endpoint Security Dynamic Application Containment rules.
VirusScan Enterprise - Access Protection Rules:
Prevent creation of new executable files in the Windows folder
Host Intrusion Prevention:
Rule ID: 111 Event Log Registry Setting Modified
Rule ID: 1020 Windows Agent Shielding - File Access
Rule ID: 2806 Attempt to create a hardlink to a file
Rule ID: 1148 CMD Tool Access by a Network Aware Application
Rule ID: 412 Double File Extension Execution
Rule ID: 6010 Generic Application Hooking Protection
