Ptrace System Calls

What the technique is

Adversaries may inject malicious code into processes via ptrace (process trace) system calls in order to evade process-based defenses as well as possibly elevate privileges. Ptrace system call injection is a method of executing arbitrary code in the address space of a separate live process. Ptrace system call injection involves attaching to and modifying a running process. The ptrace system call enables a debugging process to observe and control another process (and each individual thread), including changing memory and register values. Ptrace system call injection is commonly performed by writing arbitrary code into a running process (ex: malloc) then invoking that memory with PTRACE_SETREGS to set the register containing the next instruction to execute. Ptrace system call injection can also be done with PTRACE_POKETEXT/PTRACE_POKEDATA, which copy data to a specific address in the target processes’ memory (ex: the current address of the next instruction). Ptrace system call injection may not be possible targeting processes that are non-child processes and/or have higher-privileges. Running code in the context of another process may allow access to the process's memory, system/network resources, and possibly elevated privileges. Execution via ptrace system call injection may also evade detection from security products since the execution is masked under a legitimate process.

What MITRE says you would watch

• AN0579

  Detects ptrace-based process injection by correlating audit logs of ptrace syscalls, memory modifications (e.g., poketext, pokedata), and suspicious register manipulation on a target process not normally debugged by the originator. Alerts on processes attempting to ptrace non-child or privileged processes, especially those followed by abnormal memory or execution behavior.