A recent analysis of the LummaC2 (LUMMAC.V2) malware reveals its use of advanced obfuscation techniques, specifically leveraging indirect control flow manipulation to make reverse engineering significantly more challenging. This type of obfuscation disrupts binary analysis tools like IDA Pro and Ghidra, making it difficult for security analysts to capture execution artifacts and generate meaningful detections.
According to a detailed report from Mandiant, LummaC2’s control flow protection is achieved through dispatcher blocks. These blocks introduce indirect jumps and obscure the flow of execution by mixing original code with obfuscator-generated instructions, thus hiding the true functionality of the malware.
Dispatcher Block Types
LummaC2 uses multiple types of dispatcher blocks:
- Unconditional dispatchers: Used for most obfuscated instructions, performing encoded offset calculations to determine the next execution step.
- Conditional dispatchers: Protect blocks that include conditional jumps, fetching one of two possible destinations based on the evaluated condition.
These blocks also take different forms, such as register-based, memory-based, or mixed-order dispatchers, each designed to further hinder static analysis.
Indicators of Compromise (IOCs)
Some IOCs associated with LummaC2:
- MD5 Hashes:
- d01e27462252c573f66a14bb03c09dd2
- 5099026603c86efbcf943449cd6df54a
- 205e45e123aea66d444feaba9a846748
For more IOCs and deeper technical analysis, refer to the full Mandiant report.
MITRE ATT&CK Techniques
LummaC2’s behaviour aligns with the following MITRE ATT&CK techniques:
- T1027.001: Obfuscated Files or Information: Utilises control flow obfuscation to evade detection.
- T1055: Process Injection: Likely injects malicious code into legitimate processes to hide its presence.
- T1064: Scripting: Manipulates script-based code to affect the flow of execution.
LummaC2’s use of indirect control flow manipulation represents a significant hurdle for security analysts. By employing symbolic backward slicing, researchers can peel away the layers of obfuscation, allowing for a more effective analysis of the malware’s behaviour. For a full breakdown, see the original Mandiant post.
Further Reading
- Mandiant: Staying a Step Ahead of the DPRK IT Worker Threat
- MITRE ATT&CK: Obfuscated Files or Information (T1027.001)
- MITRE ATT&CK: Process Injection (T1055)