TLDR Tech / InfoSec
Static Devirtualization of Themida (15 minute read)
Back Engineering Labs has published a generic static devirtualization approach for Themida and CodeVirtualizer (extensible to VMProtect, vxlang, EagleVM, and other VM-based protectors) that deliberately avoids handler pattern-matching, instead lifting native instructions into BLARE2's SSA IR with all registers symbolic and RSP concretized, then running constant promotion, constant folding, dead store elimination (scoped to VM-private sections), instruction combination, and branch folding to convergence until handler addresses, VPC math, and dispatch logic collapse into concrete control flow. VM-specific knowledge is only required for Themida's VJCC handler (which writes a branch_taken_flag before advancing VIP, forcing both paths to be explored) and for VMEXIT classification via RSP displacement from initRSP — for example, a return at initRSP - 0x10 indicates a VMEXIT-CALL with target at RSP and return address at RSP + 0x8. Defenders and reverse engineers can study the released sample binaries on GitHub. Red-team tool authors should note that MBA-encoded branch targets no longer reliably defeat symbolic evaluation and that stronger anti-symbolic constructions (as in CodeDefender's higher tiers) are now required to resist this class of pipeline.
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