Trellix Insights: XLL Files Used to Deliver Infostealer Malware and Ransomware
Technical Articles ID:
KB95839
Last Modified: 2022-08-22 10:11:43 Etc/GMT
Last Modified: 2022-08-22 10:11:43 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
Description of Campaign
Using resume and purchase-order themed emails with malicious attachments, threat actors have been using MS Excel add-ins to deliver malicious payloads. Once opened and allowed, the XLL files use Excel to launch the XLL file, which retrieves its payloads from the attacker-controlled C2 server. Payloads are identified as LokiBot, which gathers and steals information, and the CARLOS ransomware, which is used to encrypt data and demand payment for the decryption key.
Our ATR team gathers and analyzes information from multiple open and closed sources before disseminating intelligence reports. This campaign was researched by AhnLabs and shared publicly.
How to use this article:
Campaign IOC
Minimum Content Versions
Detection Summary
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:Rule ID: 239 Identify suspicious command parameter execution
Rule ID: 4 Use GTI file reputation to identify trusted or malicious files
Host Intrusion Prevention:Rule ID: 6070 Hidden PowerShell Detected
Rule ID: 6113 T1055 - Fileless Threat: Reflective Self Injection
Rule ID: 6083 PowerShell Command Restriction - NonInteractive
Rule ID: 6081 PowerShell Command Restriction - NoProfile
Rule ID: 6135 Unmanaged PowerShell Detected
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: 6010 Generic Application Hooking Protection
Rule ID: 6011 Generic Application Invocation Protection
Rule ID: 1020 Windows Agent Shielding - File Access
Rule ID: 344 T1547 - New Startup Program Creation
Rule ID: 1148 CMD Tool Access by a Network Aware Application
Using resume and purchase-order themed emails with malicious attachments, threat actors have been using MS Excel add-ins to deliver malicious payloads. Once opened and allowed, the XLL files use Excel to launch the XLL file, which retrieves its payloads from the attacker-controlled C2 server. Payloads are identified as LokiBot, which gathers and steals information, and the CARLOS ransomware, which is used to encrypt data and demand payment for the decryption key.
Our ATR team gathers and analyzes information from multiple open and closed sources before disseminating intelligence reports. This campaign was researched by AhnLabs 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.
Campaign IOC
| Type | Value |
Minimum Content Versions
| Content Type | Version |
Detection Summary
| IOC | Scanner | Detection |
| IOC | Scanner | Detection |
| IOC | Scanner | Detection |
| IOC | Scanner | Detection |
| IOC | Scanner | Detection |
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:
Rule ID: 4 Use GTI file reputation to identify trusted or malicious files
Host Intrusion Prevention:
Rule ID: 6113 T1055 - Fileless Threat: Reflective Self Injection
Rule ID: 6083 PowerShell Command Restriction - NonInteractive
Rule ID: 6081 PowerShell Command Restriction - NoProfile
Rule ID: 6135 Unmanaged PowerShell Detected
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:
Host Intrusion Prevention:
Rule ID: 6011 Generic Application Invocation Protection
Rule ID: 1020 Windows Agent Shielding - File Access
Rule ID: 344 T1547 - New Startup Program Creation
Rule ID: 1148 CMD Tool Access by a Network Aware Application
