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Cyber Risks · Unit 42 Palo Alto Networks

Teasing the Secrets From Threat Actors: Malware Configuration Parsing at Scale

Summary: Unit 42 described how malware configuration data - the per-deployment elements such as C2 URLs and campaign IDs that authors keep editable without recompiling - is deliberately protected with encryption, obfuscation and compression, and showed how it decrypted an IcedID (Bokbot) sample from an attack chain discovered in early November 2022 by setting breakpoints at Memmove and WinHttpConnect and reversing the XOR loops. The stage one blob was 0x20 bytes with a key at a 0x40-byte offset, the stage two blob was 0x25c bytes with the key in its last 0x10 bytes, and the extracted stage two configuration yielded C2 domains including spkdeutshnewsupp[.]com and germanysupportspk[.]com, C2 URI news, and campaign ID 1139942657.

Bottom line: The campaign ID in that configuration links an IcedID sample back to a specific threat actor, and the C2 URLs included some that would not surface during execution of the binary - intelligence a sandbox alone would miss. Unit 42 notes the diversity of payloads makes supporting them all more or less impossible, so it prioritizes families by metrics; the parsers your detection depends on likely cover a similarly chosen subset.

Read the original at Unit 42 Palo Alto Networks ↗

Topics
Detection & Response
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