Linux Execless Enum

ShellBeak is an 'execless' Linux enumeration tool that leverages Bash built-in commands (such as read, printf, and parameter expansions) to gather extensive system information without invoking execve syscalls, which are commonly monitored by security tools. By avoiding process creation, it aims to reduce detection by EDR solutions that hook exec* syscall families. The script enumerates local accounts, process details, network interfaces, permissions, scheduled tasks, user configurations, installed software databases, GTFOBins availability, and searches for potential secrets in readable files. It requires Bash 4.4 or newer and uses a local GTFOBins list for additional enumeration. While it improves stealth, it cannot bypass all enumeration limitations inherent to Bash and does not execute external binaries during its main enumeration phase. This technique is not a vulnerability but a stealthy enumeration method that may be used in offensive security operations.

The impact is primarily on detection evasion during Linux system enumeration. By avoiding execve syscalls, the script can bypass some EDR detections that rely on monitoring process creation events. However, it does not exploit a software vulnerability or cause direct system compromise. The technique may enable attackers or penetration testers to gather system information stealthily, potentially aiding further attack stages. There are no known exploits in the wild associated with this script, and it does not itself introduce a vulnerability.

This is a technique rather than a vulnerability; no patch or official fix applies. Defenders should consider monitoring a broader range of syscalls beyond execve, such as file read and write syscalls, and implement behavioral analytics to detect unusual system activity patterns. Awareness of execless enumeration techniques can inform detection strategies. No immediate remediation is required for this script itself.