Subvert Trust Controls: SIP and Trust Provider Hijacking Defense Evasion [Mitre]

Adversaries may tamper with SIP and trust provider components to mislead the operating system and application control tools when conducting signature validation checks. In user mode, Windows Authenticode digital signatures are used to verify a file's origin and integrity, variables that may be used to establish trust in signed code (ex: a driver with a valid Microsoft signature may be …

Template Injection Defense Evasion [Mitre]

Adversaries may create or modify references in user document templates to conceal malicious code or force authentication attempts. For example, Microsoft’s Office Open XML (OOXML) specification defines an XML-based format for Office documents (.docx, xlsx, .pptx) to replace older binary formats (.doc, .xls, .ppt). OOXML files are packed together ZIP archives compromised of various XML files, referred to as parts, …

Unloading Module with FreeLibrary Antivirus/EDR Evasion

Malware authors often use various techniques to evade detection by AV/EDR solutions. One such technique involves checking for the presence of AV/EDR DLLs that may be loaded in the malware's address space and attempting to unload them before executing their malicious code.

To do this, the malware first uses the GetModuleHandleA function to retrieve a handle to the DLL, …

Evasion using direct Syscalls Antivirus/EDR Evasion

In the Windows operating system, conventional malware frequently utilizes strategies involving the invocation of specific functions from the kernel32.dll library, such as VirtualAlloc, VirtualProtect, and CreateThread. A closer inspection of the call stack reveals that the functions employed from kernel32.dll eventually trigger corresponding functions within the ntdll.dll library. This is facilitated by the ntdll.dll library, which serves …

DLL Unhooking Antivirus/EDR Evasion

Endpoint Detection and Response (EDR) tools use a technique known as hooking to monitor sensitive system functions within the DLLs of loaded processes. Hooking is a method of live-patching system DLLs, enabling EDRs to intercept the flow of a program and evaluate its legitimacy.

Here's how it works: EDRs modify the first instructions of the functions within the DLLs. …

VBA Purging Antivirus/EDR Evasion

VBA Purging is an obfuscation technique designed to evade detection mechanisms used in malware analysis. When a VBA macro is added to a Microsoft Office document, it is stored in two sections: the PerformanceCache (compiled VBA code) and the CompressedSourceCode (compressed VBA source code). In VBA Purging, the PerformanceCache (compiled code) is completely removed from the module stream, along with …

SuspendThread Anti-Debugging

Suspending threads is a technique used by malware to disable user-mode debuggers and make it more difficult for security analysts to reverse engineer and analyze the code. This can be achieved by using the SuspendThread function from the kernel32.dll library or the NtSuspendThread function from the NTDLL.DLL library.

The malware can enumerate the threads of a given process, or …

Peer to peer C2 Network Evasion

Peer-to-peer (P2P) botnets are a type of botnet that uses a decentralized network structure, without a central command and control (C&C) server. Each infected machine in a P2P botnet maintains a list of other trusted computers (including other infected machines), as well as information drop locations and locations where the malware can be updated. Some P2P botnets also use encryption …

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