System Binary Proxy Execution: Regsvcs/Regasm Defense Evasion [Mitre]

Adversaries may abuse Regsvcs and Regasm to proxy execution of code through a trusted Windows utility. Regsvcs and Regasm are Windows command-line utilities that are used to register .NET Component Object Model (COM) assemblies. Both are binaries that may be digitally signed by Microsoft.

Both utilities may be used to bypass application control through use of attributes within the …

System Binary Proxy Execution: Regsvr32 Defense Evasion [Mitre]

Adversaries may abuse Regsvr32.exe to proxy execution of malicious code. Regsvr32.exe is a command-line program used to register and unregister object linking and embedding controls, including dynamic link libraries (DLLs), on Windows systems. The Regsvr32.exe binary may also be signed by Microsoft.

Malicious usage of Regsvr32.exe may avoid triggering security tools that may not monitor execution of, and modules …

System Binary Proxy Execution: Rundll32 Defense Evasion [Mitre]

Adversaries may abuse rundll32.exe to proxy execution of malicious code. Using rundll32.exe, vice executing directly (i.e. Shared Modules), may avoid triggering security tools that may not monitor execution of the rundll32.exe process because of allowlists or false positives from normal operations. Rundll32.exe is commonly associated with executing DLL payloads (ex: rundll32.exe {DLLname, DLLfunction}).

Rundll32.exe can also be used to …

AddVectoredExceptionHandler Anti-Debugging

The AddVectoredExceptionHandler technique is an anti-debugging method that can detect the presence of debuggers using Vectored Exception Handlers. This technique works by calling AddVectoredExceptionHandler(1, ourHandler) to register a top-level exception handler that will catch any exceptions raised by the process, including those generated by debuggers.

After this call has taken place, stepping through the code will trigger an EXCEPTION_SINGLE_STEP …

Virtualization/Sandbox Evasion: System Checks Defense Evasion [Mitre]

Adversaries may employ various system checks to detect and avoid virtualization and analysis environments. This may include changing behaviors based on the results of checks for the presence of artifacts indicative of a virtual machine environment (VME) or sandbox. If the adversary detects a VME, they may alter their malware to disengage from the victim or conceal the core functions …

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. …

SMB / Named Pipes Network Evasion

Named Pipes are a feature of the Windows operating system that allow for inter-process communication (IPC) using a pipe metaphor. These are particularly useful in networking scenarios as they can be made accessible over a network and facilitate a client-server model of communication. The SMB (Server Message Block) protocol is commonly used in Windows environments for shared access to files, …

FuncIn Antivirus/EDR Evasion Anti-Debugging Anti-Disassembly Anti-Forensic

FuncIn involves a payload staging strategy wherein the entire set of malicious functionalities is not contained within the malware file itself or any third-party file/network location (e.g., a web server). Instead, these functionalities are transmitted over the network by the Command and Control (C2) server when required.

This approach addresses three primary issues in malware development. Firstly, it mitigates …

PyArmor Packers

Pyarmor is a command-line tool primarily used for the obfuscation of Python scripts. While its original design aims to protect Python code from unauthorized access and reverse engineering, its capabilities also make it a tool of interest for malware obfuscation. Pyarmor achieves this through several key features, each with potential applications in both legitimate protection and malicious exploitation:

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BlockInput Others

As per Microsoft's documentation, BlockInput function "prevents keyboard and mouse input events from reaching applications," effectively restricting user interaction with the system.

Malware occasionally employs this tactic to hinder analysis by debuggers or other analysis tools throughout the process' runtime. To deactivate the block, the program must make a live call to BlockInput with the parameter 0. Windows automatically …

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