2026-07-21 · view entry permalink →
Cruciferra: a crypter-as-a-service using kernel-aware process ghosting and BYOVD EDR termination, tied to China-nexus TA4922
Proofpoint's analysis details Cruciferra, a Mono/.NET-based crypter-as-a-service advertised on underground forums since late 2025 and used by several unrelated criminal groups to pack commodity payloads (AsyncRAT/DCRAT, Agent Tesla, XWorm, Formbook/XLoader, Remcos, Snake Keylogger and others). Its distinguishing feature is an evasion stack aimed squarely at endpoint defenses (Proofpoint, 2026-07-20). Payloads are encrypted with one of over 90 polymorphic cipher routines assembled from primitives such as Keccak, Feistel, SPECK and Threefish and stored Base16-encoded in the PE's .reloc section, so no two samples share an identical routine. Execution uses a variant of process ghosting: a temporary file is marked for deletion, then mapped as a PE image section (NtCreateSection with SEC_IMAGE) before the delete completes, leaving a running process whose backing image is never scannable on disk. Cruciferra hardens that trick with two anti-EDR steps — patching ZwQueryVirtualMemory so endpoint tools misread mapped memory, and neutering NtManageHotPatch to defeat image-integrity validation — alongside Import Address Table unhooking and indirect syscalls: per Proofpoint, "the malware reads a clean copy of ntdll.dll on disk and stores all stub pointers in a global structure for later usage." For EDR/AV termination it loads a legitimate-but-vulnerable signed driver (Proofpoint names GoFlyDrv.sys among the alternates) and issues control codes to kill security processes — classic BYOVD.
Attribution matters here: "Proofpoint observed four campaigns attributed to Chinese-speaking cybercrime actor TA4922 using Cruciferra to ultimately deliver AsyncRAT," behind landing pages mimicking government tax portals, against finance, healthcare and government targets.
the malware reads a clean copy of ntdll.dll on disk and stores all stub pointers in a global structure for later usage.
Proofpoint observed four campaigns attributed to Chinese-speaking cybercrime actor TA4922 using Cruciferra to ultimately deliver AsyncRAT.