HallWatch is a C++ user-mode detector for indirect syscalls that works by patching the actual syscall instruction (0F 05) to an INT3 breakpoint (CC 05). This approach enables detection of execution paths that reach the syscall instruction, allowing inspection and validation of the syscall number, stack unwinding, and redirection through a private trampoline. It also detects advanced syscall bypass techniques like Hell's Gate and shadow ntdll mappings by scanning executable memory for syscall stubs. The project is still in research phase and acknowledges limitations in fully detecting syscalls without debugger or tracer support.

HallWatch itself is not a vulnerability or exploit but a detection tool aimed at identifying indirect syscall usage that may be employed by malware or evasive techniques. It enhances visibility into syscall invocation in user-mode, potentially improving malware analysis and endpoint detection capabilities. There is no indication that HallWatch introduces security risks or is exploited in the wild.

This is a detection tool rather than a vulnerability requiring remediation. No patch or fix is applicable. Users interested in syscall detection and malware analysis may consider evaluating HallWatch as a lightweight research tool. Since it is a proof-of-concept, it should be used with caution and not relied upon as a sole detection mechanism.