💀 Modern Malware’s Anti-Forensics

Source: Dev.to

Abstract

High‑Retention Hook
pslist, netscan, hashdump. The results came back suspiciously clean: zero network connections, no unfamiliar processes, and no obvious strings in the kernel pool. My initial thought was tool error, but after three hours of re‑runs and profile checks, the realization hit: the malware wasn’t hiding; it was destroying the evidence path we were trained to follow. The threat actor had designed the payload specifically to defeat memory analysis.

Research Context

Problem Statement

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Methodology or Investigation Process

Tools used included:

• Targeted C++ payload implementing the evasion TTPs.
• WinPmem for reliable memory acquisition.
• Volatility 3 framework for analysis, specifically testing the windows.pslist, windows.modscan, and windows.vadinfo plugins.

The process involved injecting a payload into a benign process (e.g., svchost.exe), executing a small task (such as simulating a registry change), and then triggering a cleanup routine before the memory dump was taken.

Findings and Technical Analysis

Process Hollowing and Module Stomping Evasion

windows.modscan might flag anomalies in the DLL list or memory maps. However, when the attacker uses module stomping, they overwrite a legitimate, loaded module in memory with malicious code while maintaining the original module’s headers and structure pointers. The resulting artifact looks legitimate to pslist and modscan.

The actual malicious code resides in a VAD (Virtual Address Descriptor) marked as MEM_COMMIT, often blending into large, legitimate process memory regions. Furthermore, the attacker can manipulate the VAD tree to mark the malicious region with misleading protection flags, making it appear as initialized data rather than executable code. This requires an analyst to perform heuristic analysis based on entropy and execution patterns, moving far beyond automated artifact parsing.

Targeted Heap Data Destruction

windows.cmdline or windows.apihooks plugins looking for post‑execution artifacts find any sensitive strings or arguments simply missing. This technique aligns with the concept of post‑exploitation cleanup, making the attribution path extremely difficult and time‑consuming.

Mitigation and Defensive Strategies

• Hardware‑Assisted Memory Acquisition (HAMA): Tools utilizing hardware features like Intel VMX or AMD‑V for memory monitoring bypass operating system visibility, making it much harder for user‑mode malware to tamper with the acquisition process.

• Kernel Callback Monitoring: Implement deep kernel‑level monitoring (using tools like Sysmon or specialized EDRs) to track memory allocation, process injection attempts, and VAD modifications in real time. This captures the TTP during execution before the cleanup routine runs.

• Heuristic Analysis and Entropy Profiling: Instead of relying on specific structure parsing, DFIR teams should profile memory regions for high entropy (indicating packed or encrypted data) combined with execution permissions. Anomalously high entropy in a non‑standard memory region within a typically low‑entropy process (like svchost.exe) is a strong indicator of malicious injection, even if the surrounding structures appear clean.

Researcher Reflection

Career and Research Implications

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Conclusion

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Discussion Question

How can investigators today ensure evidence continuity in volatile environments?