modifications

A recent study has revealed a method that bypasses Microsoft’s Windows Defender antivirus by using direct system calls and XOR encryption techniques, exposing vulnerabilities in the security solution. The technique targets the user mode and kernel mode operations of Windows, allowing attackers to execute harmful code without detection. Researchers demonstrated that by directly invoking syscall instructions, they could evade security monitoring that typically occurs at the user mode level. They utilized XOR encryption to obfuscate malicious shellcodes, making them unrecognizable and undetectable by signature-based systems. Tests showed that a Meterpreter reverse shell payload, encrypted with XOR and executed via direct syscalls, successfully bypassed Windows Defender protections without leaving traces on the disk. This method has been effective since at least 2022 and continues to work against recent updates of Windows Defender. The researchers recommend that Microsoft enhance defenses with kernel-level monitoring of syscalls and advise organizations to implement additional security measures beyond Windows Defender.