Indicator Removal: Clear Command History
Created the Tuesday 07 February 2023. Updated 1 month, 2 weeks ago.
In addition to clearing system logs, an adversary may clear the command history of a compromised account to conceal the actions undertaken during an intrusion. Various command interpreters keep track of the commands users type in their terminal so that users can retrace what they've done.
On Windows hosts, PowerShell has two different command history providers: the built-in history and the command history managed by the PSReadLine module. The built-in history only tracks the commands used in the current session. This command history is not available to other sessions and is deleted when the session ends.
The PSReadLine command history tracks the commands used in all PowerShell sessions and writes them to a file ($env:APPDATA\Microsoft\Windows\PowerShell\PSReadLine\ConsoleHost_history.txt by default). This history file is available to all sessions and contains all past history since the file is not deleted when the session ends.
Adversaries may run the PowerShell command Clear-History to flush the entire command history from a current PowerShell session. This, however, will not delete/flush the ConsoleHost_history.txt file. Adversaries may also delete the ConsoleHost_history.txt file or edit its contents to hide PowerShell commands they have run.
The resources provided below are associated links that will give you even more detailed information and research on current evasion technique. It is important to note that, while these resources may be helpful, it is important to exercise caution when following external links. As always, be careful when clicking on links from unknown sources, as they may lead to malicious content.