Clear Command History

A subject clears bash terminal command history to prevent executed commands from being reviewed, disclosing information about the subject’s activities.

The Command Prompt on Windows only stores command history within the current session, once Command Prompt is closed, the history is lost.

On Linux-based operating systems different terminal software may store command history in various locations, with the most common being /home/%username%/.bash_history. Using the command history -c will clear the history for the current session, preventing it from being written to .bash_history when the session ends.

On MacOS the Terminal utility will write command history to /Users/%username%/.zsh_history or /Users/%username%/.bash_history based on operating system version.

A subject clears PowerShell command history to prevent executed commands from being reviewed, disclosing information about the subject’s activities.

PowerShell stores command history in the context of a user account. This file is located at C:/Users/%username%/AppData/Roaming/Microsoft/Windows/PowerShell/PSReadline.

A subject can delete their own PSReadline file without any special permissions.

A subject may attempt to use the Clear-History Cmdlet, however this will only clear commands from the current session, does not affect the PSReadline history file.

This section cannot be readily mitigated at a system level with preventive controls since it is based on the abuse of fundamental features of the system.

The .bash_history file, located within a user's directory on MacOS and Linux, is written with command history from shell sessions.

If the file has a Created timestamp, but a user has used a shell utility previously, this may indicate the file was deleted and manually or automatically re-created.

Recent modifications to the ConsoleHost_history.txt file located in C:\Users\%username%\AppData\Roaming\Microsoft\Windows\PowerShell\PSReadLine may indicate the file has been deleted and subsequently automatically recreated by the Operating System. This may represent an anti-forensics technique if the subject in question is known to have used PowerShell any time prior to the “Created” timestamp of the ConsoleHost_history.txt file.

If the ConsoleHost_history.txt file located in C:\Users\%username%\AppData\Roaming\Microsoft\Windows\PowerShell\PSReadLine, is missing, this indicates that the file has been deleted. This may represent an anti-forensics technique if the subject in question is known to have used PowerShell any time.

The .bash_history file, located within a user's directory on MacOS and Linux, is written with command history from shell sessions.

If the file is missing, this could indicate that it has been deleted, if a user account has used a shell utility previously.