T1562.003: Impair Command History Logging
Adversaries may impair command history logging to hide commands they run on a compromised system. Various command interpreters keep track of the commands users type in their terminal so that users can retrace what they've done.
On Linux and macOS, command history is tracked in a file pointed to by the environment variable HISTFILE
. When a user logs off a system, this information is flushed to a file in the user's home directory called ~/.bash_history
. The HISTCONTROL
environment variable keeps track of what should be saved by the history
command and eventually into the ~/.bash_history
file when a user logs out. HISTCONTROL
does not exist by default on macOS, but can be set by the user and will be respected.
Adversaries may clear the history environment variable (unset HISTFILE
) or set the command history size to zero (export HISTFILESIZE=0
) to prevent logging of commands. Additionally, HISTCONTROL
can be configured to ignore commands that start with a space by simply setting it to "ignorespace". HISTCONTROL
can also be set to ignore duplicate commands by setting it to "ignoredups". In some Linux systems, this is set by default to "ignoreboth" which covers both of the previous examples. This means that “ ls” will not be saved, but “ls” would be saved by history. Adversaries can abuse this to operate without leaving traces by simply prepending a space to all of their terminal commands.
On Windows systems, the PSReadLine
module tracks commands used in all PowerShell sessions and writes them to a file ($env:APPDATA\Microsoft\Windows\PowerShell\PSReadLine\ConsoleHost_history.txt
by default). Adversaries may change where these logs are saved using Set-PSReadLineOption -HistorySavePath {File Path}
. This will cause ConsoleHost_history.txt
to stop receiving logs. Additionally, it is possible to turn off logging to this file using the PowerShell command Set-PSReadlineOption -HistorySaveStyle SaveNothing
.
Adversaries may also leverage a Network Device CLI on network devices to disable historical command logging (e.g. no logging
).
Positive Technologies products that cover the technique
MaxPatrol SIEM knowledge base
eltex: PT-CR-2321: Eltex_Fastpath_disable_logging: Logging settings were changed
eltex: PT-CR-2345: Eltex_Ros_disable_logging: Logging was disabled or its settings were changed
unix_mitre_attck_defense_evasion: PT-CR-1658: Unix_Impair_Command_Logging: Command history log setting change
Detection
ID | DS0013 | Data source and component | Sensor Health: Host Status | Description | Users checking or changing their |
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ID | DS0017 | Data source and component | Command: Command Execution | Description | Correlating a user session with a distinct lack of new commands in their |
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Mitigation
ID | M1028 | Name | Operating System Configuration | Description | Make sure that the |
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ID | M1039 | Name | Environment Variable Permissions | Description | Prevent users from changing the |
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