Full Report
This blog post provides a detailed look at the TTPs of a ransomware affiliate operator. In this case, the endpoint had been moved to another infrastructure (as illustrated by various command lines, and confirmed by the partner), so while Huntress SOC analysts reported the activity to the partner, no Huntress customer was impacted by the ransomware deployment.
Analysis Summary
# Tool/Technique: BlackCat (ALPHV) Ransomware
## Overview
BlackCat (also known as ALPHV or Noberus) is a sophisticated Ransomware-as-a-Service (RaaS) operation. It is notable for being one of the first major malware families written in the Rust programming language, allowing for high performance and easier cross-platform porting. The threat actors associated with this tool often employ "triple extortion" tactics: encrypting data, stealing sensitive information for ransom, and threatening Distributed Denial of Service (DDoS) attacks.
## Technical Details
- **Type:** Malware family (Ransomware-as-a-Service)
- **Platform:** Windows, Linux, VMware ESXi
- **Capabilities:** High-speed encryption (Rust-based), lateral movement, credential theft, data exfiltration, and self-propagation.
- **First Seen:** Approximately November 2021
## MITRE ATT&CK Mapping
- **[TA0001 - Initial Access]**
- [T1190 - Exploit Public-Facing Application] (e.g., ScreenConnect vulnerabilities)
- [T1133 - External Remote Services]
- **[TA0003 - Persistence]**
- [T1133 - External Remote Services] (Use of RMM tools like ScreenConnect)
- **[TA0005 - Defense Evasion]**
- [T1562.001 - Impair Defenses: Disable or Modify Tools] (Targeting Canary files/Antivirus)
- **[TA0010 - Exfiltration]**
- [T1567.002 - Exfiltration Over Web Service: Exfiltration to Cloud Storage] (Use of backup utilities)
- **[TA0040 - Impact]**
- [T1486 - Data Encrypted for Impact]
## Functionality
### Core Capabilities
- **Rust-Based Execution:** Highly customizable and difficult to reverse-engineer compared to traditional C++ malware.
- **Data Encryption:** Uses strong encryption algorithms to lock files on local drives and network shares.
- **Credential Harvesting:** Often bundled with scripts or tools to dump credentials from memory (LSASS).
### Advanced Features
- **RMM Exploitation:** Leverages compromised Remote Monitoring and Management (RMM) tools (like ScreenConnect) for initial access and persistence.
- **Evasion of "Canary" Files:** Designed to detect and modify "canary" files used by defenders to trigger ransomware alerts.
- **Multi-Platform Targeting:** Specifically includes variants capable of encrypting Linux servers and ESXi virtual machines.
## Indicators of Compromise
- **File Names:** `BlackCat` (or variants thereof), legitimate backup utility names used for exfiltration.
- **Network Indicators:**
- `REDACTED.ddns[.]net` (C2/RMM callback)
- Specific ScreenConnect instances connecting to unauthorized DDNS domains.
- **Behavioral Indicators:**
- Modification of "Ransomware Canary" files.
- Unauthorized installation or update of ScreenConnect (versions like 21.15.6764.8075).
- Sudden appearance of `chlsln14` or other unauthorized usernames in RMM logs.
## Associated Threat Actors
- **ALPHV / BlackCat Affiliates** (Specific affiliate identified by the use of the `chlsln14` username).
## Detection Methods
- **Signature-based detection:** Huntress Managed Antivirus and other EDRs track the specific Rust-based binary signatures.
- **Behavioral detection:** Monitoring for the modification of canary files and rapid file encryption activities.
- **Log Analysis:** Auditing RMM (ScreenConnect) logs for unauthorized connections from unfamiliar usernames or connections to dynamic DNS (DDNS) providers.
## Mitigation Strategies
- **Patch Management:** Immediately update ScreenConnect to version 23.9.8 or higher to mitigate authentication bypass vulnerabilities.
- **Access Control:** Implement Multi-Factor Authentication (MFA) on all remote access and RMM tools.
- **Network Segmentation:** Restrict RMM tool communication to known, authorized IP addresses.
- **Inventory Management:** Regularly audit active agents to ensure retired or moved hardware is no longer reporting to the production infrastructure.
## Related Tools/Techniques
- **ScreenConnect:** Remote management tool frequently abused by BlackCat affiliates.
- **Noberus:** An alternative name for the BlackCat malware family.
- **Akira / Qilin / INC Ransom:** Other ransomware families using similar affiliate-based TTPs.