XSL Script Processing Defense Evasion [Mitre]

Adversaries may bypass application control and obscure execution of code by embedding scripts inside XSL files. Extensible Stylesheet Language (XSL) files are commonly used to describe the processing and rendering of data within XML files. To support complex operations, the XSL standard includes support for embedded scripting in various languages.

Adversaries may abuse this functionality to execute arbitrary files …

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. …

Right-to-Left Override (RLO) Extension Spoofing Others

The Right-to-Left Override (RLO) character (U+202E) is a Unicode control character used for bidirectional text formatting. It affects the way text is displayed, causing text following the RLO character to be rendered from right to left, which is typically used in languages like Arabic and Hebrew.

However, malicious actors have found a way to exploit this Unicode …

EasyCrypter Packers

EasyCrypter is the crypter that is being sold via an automated bot on Telegram. The crypter uses a method known as "mutation", which involves replacing instructions in the file with their analogues or a sequence of instructions that yield the same outcome as the original code. EasyCrypter supports a maximum file size of 5MB and is only applicable for x86 …

PureCrypter Packers

PureCrypter, a multi-functional crypter/loader developed in C#, was first introduced in hacking forums on March 17, 2021. This tool is compatible with both 32-bit and 64-bit native as well as .NET payloads. It features multiple injection modes, including reflection, RunPE, and shellcode. PureCrypter can deliver payloads either via a URL or offline. It has been noted for its use in …

PowerShell Special Characters Obfuscation Data Obfuscation

PowerShell scripts can be obfuscated using methods that encode commands exclusively with special characters. This technique aims to complicate analysis and potentially evade detection mechanisms.

Attackers frequently employ these tactics to hide the true functionalities of the script, making the analysis more challenging.

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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Runtime Function Decryption Antivirus/EDR Evasion

This technique is used to store the function body in an encrypted form. They will only be decrypted just before the execution of that code and will be re-encrypted after the code has been executed.

This technique is used by SmokeLoader to evade anti-virus and EDRs, since the function body is in encrypted form except at the time of …

AppInit DLL Injection Process Manipulating Defense Evasion [Mitre]

Any Dynamic Link Libraries (DLL) that are specified within the AppInit_DLLs registry key values are loaded by user32.dll into any process that utilizes user32.dll. So by modifying the AppInit_DLLs registry key value and pointing it to a malicious DLL, an attacker can force the system to load their DLL into every process that utilizes user32.dll and force it to execute …

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