Full Report
Key Takeaways In December 2023, we observed an intrusion that started with the execution of a Cobalt Strike beacon and ended in the deployment of BlackSuit ransomware. The threat actor … Read More
Analysis Summary
# Tool/Technique: BlackSuit Ransomware (Contextual)
Given the context, this summary focuses on the overall intrusion where BlackSuit ransomware was the final payload, utilizing multiple tools and techniques.
## Overview
This documents an intrusion observed in December 2023 that commenced with the execution of a Cobalt Strike beacon and culminated in the deployment of the BlackSuit ransomware. The threat actor utilized a combination of specialized third-party tools alongside built-in system utilities for reconnaissance, privilege escalation, and lateral movement.
## Technical Details
- Type: Malware (Ransomware payload, deployed following initial compromise and C2 activity)
- Platform: Windows (Inferred from tools like Rubeus, Sharphound, and standard system utilities)
- Capabilities: Encryption of data leading to system impact/extortion.
- First Seen: Intrusion began December 2023
## MITRE ATT&CK Mapping
The mapping below reflects the techniques used *leading up to* and *including* the final impact, as described in the context:
- **TA0002 - Execution**
- T1059.001 - PowerShell
- T1569.002 - Service Execution
- **TA0008 - Lateral Movement**
- T1021.002 - SMB/Windows Admin Shares
- **TA0003 - Persistence**
- T1547.001 - Registry Run Keys / Startup Folder (Inferred, though not explicitly detailed for persistence here)
- **TA0004 - Privilege Escalation**
- T1558.004 - AS-REP Roasting
- T1558.003 - Kerberoasting
- **TA0009 - Collection**
- T1003.001 - LSASS Memory (Credential Dumping)
- **TA0010 - Command and Control**
- T1090 - Proxy (Via CloudFlare)
- T1071.001 - Web Protocols (Cobalt Strike C2)
- **TA0011 - Exfiltration**
- T1560 - Archive Collected Data
- **TA0007 - Discovery**
- T1082 - System Information Discovery
- T1482 - Domain Trust Discovery
- T1518.001 - Security Software Discovery
- T1518 - Software Discovery
- **TA0006 - Credential Access**
- T1550.002 - Pass the Hash (Inferred given credential access/lateral movement)
- **TA0001 - Initial Access**
- T1204.002 - Malicious File (Execution of Cobalt Strike beacon)
- **TA0005 - Defense Evasion**
- T1055 - Process Injection (Implied by in-memory Cobalt Strike execution)
- **TA000A - Impact**
- T1486 - Data Encrypted for Impact (BlackSuit Ransomware activity)
- T1490 - Inhibit System Recovery
## Functionality
### Core Capabilities
- Initial C2 establishment via Cobalt Strike beacon.
- System and environment enumeration using built-in tools (`systeminfo`, `nltest`).
- Credential theft via AS-REP Roasting and Kerberoasting against domain controllers.
- Discovery of Active Directory structures using Sharphound.
- Lateral movement via transferring and executing Cobalt Strike over SMB.
- Credential dumping from LSASS memory on subsequent hosts.
- Final payload deployment: BlackSuit Ransomware encryption.
### Advanced Features
- **C2 Obfuscation/Proxying:** Command and control traffic was proxied through CloudFlare to conceal the actual team server IP address.
- **In-Memory Execution:** Utilization of Rubeus and Sharphound executed entirely in memory via Cobalt Strike to reduce disk artifacts.
- **Output Saving:** Sharphound output was saved to disk, likely for later review or exfiltration preparation.
## Indicators of Compromise
*Note: Specific IOCs were not extracted as they were summarized in the linked "Indicators" section of the original article.*
- File Hashes: [Not explicitly provided in the summary text]
- File Names: [Not explicitly provided in the summary text, but related to tool usage]
- Registry Keys: [T1547.001 artifacts likely present]
- Network Indicators: C2 traffic beaconed to IP addresses managed by `cloudflare[.]com` (used as proxy).
- Behavioral Indicators: Large-sized Cobalt Strike beacon execution, execution of Rubeus and Sharphound in memory, use of `systeminfo` and `nltest` shortly after initial execution.
## Associated Threat Actors
- Unknown/Unspecified in the description, associated with the deployment of BlackSuit ransomware.
## Detection Methods
The DFIR report suggests capabilities for detection:
- Detection Methods: The DFIR report offers comprehensive detection techniques tied to the noted ATT&CK behaviors (e.g., detection rules for Cobalt Strike patterns, PowerShell logging).
- YARA rules: Multiple YARA rules are listed as being associated with various Cobalt Strike payloads and configurations in the source material appendices.
## Mitigation Strategies
- **Network Segmentation:** Mitigate lateral movement over SMB.
- **Credential Protection:** Implement Tiering models and LSA protection to defend against LSASS dumping and credential attacks (AS-REP Roasting/Kerberoasting).
- **Endpoint Detection & Response (EDR):** Monitor for in-memory execution of known offensive frameworks like Cobalt Strike, Rubeus, and Sharphound.
- **C2 Policy:** Restrict or closely monitor outbound traffic to known CDN/Proxy services if they are being abused for malicious C2 hiding.
- **Vulnerability Management:** Address initial access vectors which remain unclear.
## Related Tools/Techniques
- Cobalt Strike (Beacon)
- Sharphound (AD Discovery)
- Rubeus (Kerberos credential attacks)
- SystemBC (Mentioned in associated toolset)
- ADFind (Mentioned in associated toolset)
- Windows built-in utilities (`systeminfo`, `nltest`)