Query: EDR alert: possible Clear Command History (T1070.003)
Matching passage: T1070.003 Clear Command History. Tactics: stealth. Description: 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 Linux and macOS, these command histories can be accessed in a few different ways. While logged in, this command history is tracked in a file pointed to by the environment variable <code>HISTFILE</code>. When a user logs off a system, this information is flushed to a file in the user's home directory called <code>~/.bash_history</code>. The benefit of this is that it allows users to go back to commands they've used before in different sessions. Adversaries may delete their commands from these logs by manually clearing the history (<code>history -c</code>) or deleting the bash history file <code>rm ~/.bash_history</code>. Adversaries may also leverage a [Network Device CLI](https://attack.mitre.org/techniques/T1059/008) on network devices to clear command history data (<code>clear logging</code> and/or <code>clear history</code>).(Citation: US-CERT-TA18-106A) On ESXi servers, command history may be manually removed from the `/var/log/shell.log` file.(Citation: Broadcom ESXi Shell Audit) On Windows hosts, PowerShell has two different command history providers: the built-in history and the command history managed by the <code>PSReadLine</code> 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 <code>PSReadLine</code> command history tracks the commands used in all PowerShell sessions and writes them to a file (<code>$env:APPDATA\Microsoft\Windows\PowerShell\PSReadLine\ConsoleHost_history.txt</code> 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.(Citation: Micros
Near-miss passage: T1070.007 Clear Network Connection History and Configurations. Tactics: stealth. Description: Adversaries may clear or remove evidence of malicious network connections in order to clean up traces of their operations. Configuration settings as well as various artifacts that highlight connection history may be created on a system and/or in application logs from behaviors that require network connections, such as [Remote Services](https://attack.mitre.org/techniques/T1021) or [External Remote Services](https://attack.mitre.org/techniques/T1133). Defenders may use these artifacts to monitor or otherwise analyze network connections created by adversaries. Network connection history may be stored in various locations. For example, RDP connection history may be stored in Windows Registry values under (Citation: Microsoft RDP Removal): * <code>HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Default</code> * <code>HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Servers</code> Windows may also store information about recent RDP connections in files such as <code>C:\Users\\%username%\Documents\Default.rdp</code> and `C:\Users\%username%\AppData\Local\Microsoft\Terminal Server Client\Cache\`.(Citation: Moran RDPieces) Similarly, macOS and Linux hosts may store information highlighting connection history in system logs (such as those stored in `/Library/Logs` and/or `/var/log/`).(Citation: Apple Culprit Access)(Citation: FreeDesktop Journal)(Citation: Apple Unified Log Analysis Remote Login and Screen Sharing) Malicious network connections may also require changes to third-party applications or network configuration settings, such as [Disable or Modify System Firewall](https://attack.mitre.org/techniques/T1686) or tampering to enable [Proxy](https://attack.mitre.org/techniques/T1090). Adversaries may delete or modify this data to conceal indicators and/or impede defensive analysis.