Windows Command Shell
The Windows command shell (cmd.exe) is a command-line interface on Windows operating systems that allows users and programs to execute a wide variety of system commands and utilities. While a legitimate tool, malicious actors often abuse the Windows command shell during the course of an attack.
Description and Technique
Adversaries may abuse the Windows command shell to execute malicious code or commands. The cmd.exe executable is just one way to interact with the Windows command shell - others include the command-line window or "console" co-hosted by newer shells such as PowerShell, or through a gsecdworker.exe remote session.
The Windows command shell provides access to a wide range of utilities and commands, some of them capable of destructive, credential harvesting, or other malicious actions. Examples include net.exe for connecting to remote systems, wmic.exe for local and remote information gathering, and fsutil.exe for file and disk operations.
Mitigation
To mitigate abuse of the Windows command shell, organizations should:
- >Use whitelisting tools to prevent unknown or unauthorized software from executing
- Configure PowerShell execution policies to prevent powershell.exe from being leveraged
- Implement behavioral prevention on command-line actions that could potentially be malicious
- Restrict permissions to cmd.exe and key Windows utilities
Detection
Signs that a Windows command shell may be abused include:
- Execution of cmd.exe by unexpected programs or user accounts
- Suspicious command line parameters being passed to cmd.exe or utilities like net.exe
- Unusual process relationships involving cmd.exe, powershell.exe, or other interpreters
- Windows Audit logs showing unusual command shell activities or spawned processes
Defenders can leverage Sysmon, PowerShell logging, and other security tools to capture and alert on suspicious command shell activities.