Adversaries may abuse utilities that allow for command execution to bypass security restrictions that limit the use of command-line interpreters. Various Windows utilities may be used to execute commands, possibly without invoking cmd. For example, Forfiles, the Program Compatibility Assistant (`pcalua.exe`), components of the Windows Subsystem for Linux (WSL), `Scriptrunner.exe`, as well as other utilities may invoke the execution of programs and commands from a Command and Scripting Interpreter, Run window, or via scripts.(Citation: VectorSec ForFiles Aug 2017)(Citation: Evi1cg Forfiles Nov 2017)(Citation: Secure Team - Scriptrunner.exe)(Citation: SS64)(Citation: Bleeping Computer - Scriptrunner.exe) Adversaries may also abuse the `ssh.exe` binary to execute malicious commands via the `ProxyCommand` and `LocalCommand` options, which can be invoked via the `-o` flag or by modifying the SSH config file.(Citation: Threat Actor Targets the Manufacturing industry with Lumma Stealer and Amadey Bot) Adversaries may abuse these features for Stealth, specifically to perform arbitrary execution while subverting detections and/or mitigation controls (such as Group Policy) that limit/prevent the usage of cmd or file extensions more commonly associated with malicious payloads.
Cause→effect chain: (1) A user or service launches an indirection utility (e.g., forfiles.exe, pcalua.exe, wsl.exe, scriptrunner.exe, ssh.exe with -o ProxyCommand/LocalCommand). (2) That utility spawns a secondary program/command (PowerShell, cmd, msiexec, regsvr32, curl, arbitrary EXE) and/or opens outbound network connections. (3) Optional precursor modification of SSH config to persist LocalCommand/ProxyCommand. Correlate process creation, command/script content, file access to %USERPROFILE%\.ssh\config, and network connections from the utility or its child.