File Splitting Antivirus/EDR Evasion

An old trick consists to split the malicious file into different parts and analyse all of them separately with and AV. The chunk where the detection is still being triggered is actually the part of the file that need to change to evade the antivirus software you are targeting.

Bad String Format Anti-Debugging

Bad string format is a technique used by malware to evade detection and analysis by OllyDbg, a popular debugger used by security researchers and analysts. This technique involves using malformed strings that exploit a known bug in OllyDbg, causing the debugger to crash or behave unexpectedly.

For example, the malware may use a string with multiple %s inputs, which …

Performing Code Checksum Anti-Debugging

Adversaries may use code checksumming to detect if their code has been modified or tampered with. This technique involves calculating a checksum or hash of the code, storing it, and then periodically checking the current checksum against the stored one. If the checksums do not match, it indicates that the code has been modified and the adversary's code can take …

Interrupts Anti-Debugging

Adversaries may use exception-based anti-debugging techniques to detect whether their code is being executed in a debugger. These techniques rely on the fact that most debuggers will trap exceptions and not immediately pass them to the process being debugged for handling.

By triggering an exception and checking whether it is handled properly, the adversary's code can determine whether it …

Process Camouflage, Masquerading Process Manipulating

Masquerading is a technique used by malware to evade detection by disguising itself as a legitimate file. This is typically achieved by renaming the malicious file to match the name of a commonly found and trusted file, such as svchost.exe, and placing it in a legitimate folder.

Masquerading can occur when the name or location of an executable, …

Hook Injection Process Manipulating

Hook injection is a technique used by malware to alter the behavior of internal functions in an operating system or application. This is typically achieved by inserting malicious code into existing function calls, allowing the malware to intercept and manipulate the normal flow of execution.

In the case of Windows, the SetWindowsHookEx function can be used by programs to …

FIleless Mechanisms Process Manipulating

Fileless malware is a type of malware that is designed to reside and execute entirely in the memory of a host system, without leaving any trace on the local disk. This can make it more difficult for security tools to detect and remove the malware, as it does not leave any files on the system that can be scanned or …

XOR Operation Data Obfuscation

The XOR operation is a common technique used by malware to hide data. This is because it is a simple and reversible function, meaning that the same operation can be used to both encode and decode data. In the XOR operation, a key is used to create a ciphertext, which is then used to encrypt the original data.

The …

Caesar Cipher Data Obfuscation

The Caesar Cipher is a simple encoding algorithm that was used during the Roman Empire to hide secret messages. In this algorithm, each letter of the plaintext is replaced with a letter that is a fixed number of positions down the alphabet. For example, if the shift value is 3, then the letter "A" would be replaced with "D", "B" …

ROL Data Obfuscation

ROL, or Rotate Left, is a simple encoding algorithm similar to the Caesar Cipher. In the ROL algorithm, each letter of the plaintext is replaced with a letter that is a fixed number of positions down the alphabet. For example, if the rotation value is 3, then the letter "A" would be replaced with "D", "B" would be replaced with …

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