Antivirus Evasion for Beginners: A Step-by-Step Guide to Bypassing AV for Penetration Testers

Antivirus Evasion refers to a set of techniques used to bypass the protective mechanisms of antivirus (AV) software, which is designed to detect and prevent malicious activities on a system. For hackers, the ability to evade AV detection is crucial in carrying out undetected attacks, whether it’s for exploiting vulnerabilities, deploying malware, or executing payloads. Here’s how this concept is viewed:

Avoiding Signature-Based Detection: Traditional AV software uses signature-based detection, which compares files and programs against a database of known malware. By modifying the code of the payloads — either through obfuscation, encryption, or polymorphic techniques — hackers can create variants of their malware that don’t match the signatures of known threats. These modifications allow the malware to sneak past signature-based detection.Bypassing Heuristic and Behavioral Analysis: More advanced AV solutions employ heuristic and behavioral analysis to detect unknown threats by their actions (e.g., file system manipulation, unusual network activity). To bypass these, hackers use living off the land techniques (abusing legitimate system tools like PowerShell, WMI, or other system scripts) to execute payloads in a manner that appears normal. This means executing their malicious code without triggering behavioral flags set by the AV software.