Simplifying MBA obfuscation with CoBRA
Summary: Trail of Bits released CoBRA, an open-source tool that simplifies Mixed Boolean-Arithmetic obfuscation by routing each expression through a worklist-based orchestrator managing 36 passes across linear, semilinear, polynomial, and mixed families. CoBRA simplified 99.86% of 73,066 expressions drawn from SiMBA, GAMBA, OSES, and four other independent sources, verifying every result against random inputs or with Z3 before returning it.
What you should know: The 106 unsupported expressions are carry-sensitive mixed-domain cases where bitwise and arithmetic operations interact in ways current techniques cannot decompose - the same class of expression an obfuscator can use to stall your reverse engineering, and CoBRA reports them as unsupported rather than guessing wrong.
Read the original at Trail of Bits Blog ↗
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