Home/ATT&CK Technique/Clear Command History
ATT&CK Technique

Clear Command History

T1070.003 · stealth

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 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 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 (history -c) or deleting the bash history file rm ~/.bash_history. Adversaries may also leverage a Network Device CLI on network devices to clear command history data (clear logging and/or clear history). On ESXi servers, command history may be manually removed from the /var/log/shell.log file.

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.

ESXiLinuxmacOSNetwork DevicesWindows
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Actors Using This

4
chinaAPT41
north_koreaLazarus Group
chinaSalt Typhoon
china_state_sponsored_mandiant_unc3886_virtualization_firewall_zero_day_specialistUNC3886
◈

Likely Attack Path

Techniques the same actors pair with this one distinctively - those showing up among actors who use this technique noticeably more than across all actors (lift > 1.15), grouped by kill-chain phase. The × is that lift multiplier; the shared-actor count is in the tooltip. A near-universal technique pairs with everything at baseline, so its list is short by design.
initial-access same
T1195.002 · Compromise Software Supply Chain ×6.38T1195 · Supply Chain Compromise ×4.35
execution same
T1047 · Windows Management Instrumentation ×3.19
persistence same
T1542 · Pre-OS Boot ×12.75T1505 · Server Software Component ×3.05
privilege-escalation same
T1055.001 · Dynamic-link Library Injection ×3.80T1134 · Access Token Manipulation ×3.31T1055 · Process Injection ×2.98
discovery same
T1012 · Query Registry ×3.13T1046 · Network Service Discovery ×2.98
lateral-movement same
T1021.004 · SSH ×3.64
command-and-control same
T1008 · Fallback Channels ×29.75
exfiltration same
T1048.003 · Exfiltration Over Unencrypted Non-C2 Protocol ×3.50T1048 · Exfiltration Over Alternative Protocol ×2.48
other same
T1553.002 · Code Signing ×4.35
▸

Atomic Tests

14
Executable Atomic Red Team test cases for exercising this technique in a lab. Copy a command, run it on the listed platform, confirm your detections fire.
shlinux, macosClear Bash history (rm)
Clears bash history via rm 
rm #{history_path}
shlinuxClear Bash history (echo)
Clears bash history via echo 
echo "" > #{history_path}
shlinux, macosClear Bash history (cat dev/null)
Clears bash history via cat /dev/null 
cat /dev/null > #{history_path}
shlinux, macosClear Bash history (ln dev/null)
Clears bash history via a symlink to /dev/null 
ln -sf /dev/null #{history_path}
shlinuxClear Bash history (truncate)
Clears bash history via truncate 
truncate -s0 #{history_path}
shlinux, macosClear history of a bunch of shells
Clears the history of a bunch of different shell types by setting the history size to zero 
unset HISTFILE
export HISTFILESIZE=0
history -c
bashlinux, macosClear and Disable Bash History Logging
Clears the history and disable bash history logging of the current shell and future shell sessions 
set +o history
echo 'set +o history' >> ~/.bashrc
. ~/.bashrc
history -c
shlinux, macosUse Space Before Command to Avoid Logging to History
Using a space before a command causes the command to not be logged in the Bash History file 
hostname
whoami
shlinuxDisable Bash History Logging with SSH -T
Keeps history clear and stays out of lastlog,wtmp,btmp ssh -T keeps the ssh client from catching a proper TTY, which is what usually gets logged on lastlog 
sshpass -p 'pwd101!' ssh testuser1@localhost -T hostname
bashelevatedlinuxClear Docker Container Logs
Clears Docker container logs using the Docker CLI and the truncate command, removing all log entries. 
docker container prune -f && sudo truncate -s 0 /var/lib/docker/containers/*/*-json.log
powershellwindowsPrevent Powershell History Logging
Prevents Powershell history 
Set-PSReadlineOption -HistorySaveStyle SaveNothing
powershellwindowsClear Powershell History by Deleting History File
Clears Powershell history 
Remove-Item (Get-PSReadlineOption).HistorySavePath
powershellwindowsSet Custom AddToHistoryHandler to Avoid History File Logging
The "AddToHistoryHandler" receives the current command as the $line variable and then returns $true if the line should be written to the history file. Here we simply return $false so nothing gets added to the history file for the current session. 
Set-PSReadLineOption -AddToHistoryHandler { return $false }
powershellwindowsClear PowerShell Session History
This technique involves using the Clear-History cmdlet in PowerShell to remove all records of previously executed commands. This action is often performed by attackers to eliminate traces of their activities, making incident detection and forensic investigation more challenging. By clearing the session history, adversaries aim to obfuscate their operational footprint. 
Clear-History
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Mitigations

3
MITRE ATT&CK mitigations - vendor-agnostic guidance for reducing exposure to this technique.
M1022Restrict File and Directory Permissions

Restricting file and directory permissions involves setting access controls at the file system level to limit which users, groups, or processes can read, write, or execute files. By configuring permissions appropriately, organizations can reduce the attack surface for adversaries seeking to access sensitive data, plant malicious code, or tamper with system files.

Enforce Least Privilege Permissions
  • Remove unnecessary write permissions on sensitive files and directories.
  • Use file ownership and groups to control access for specific roles. Example (Windows): Right-click the shared folder.
  • Properties.
  • Security tab.
  • Adjust permissions for NTFS ACLs.
Harden File Shares
  • Disable anonymous access to shared folders.
  • Enforce NTFS permissions for shared folders on Windows. Example: Set permissions to restrict write access to critical files, such as system executables (e.g., /bin or /sbin on Linux). Use tools like chown and chmod to assign file ownership and limit access. On Linux, apply: chmod 750 /etc/sensitive.conf `chown root:admin /etc/sensitive.
conf` File Integrity Monitoring (FIM)
  • Use tools like Tripwire, Wazuh, or OSSEC to monitor changes to critical file permissions.
Audit File System Access
  • Enable auditing to track permission changes or unauthorized access attempts.
  • Use auditd (Linux) or Event Viewer (Windows) to log activities.
Restrict Startup Directories
  • Configure permissions to prevent unauthorized writes to directories like C:\ProgramData\Microsoft\Windows\Start Menu. Example: Restrict write access to critical directories like /etc/, /usr/local/, and Windows directories such as C:\Windows\System32.
  • On Windows, use icacls to modify permissions: icacls "C:\Windows\System32" /inheritance:r /grant:r SYSTEM:(OI)(CI)F.
  • On Linux, monitor permissions using tools like lsattr or auditd.
M1029Remote Data Storage

Remote Data Storage focuses on moving critical data, such as security logs and sensitive files, to secure, off-host locations to minimize unauthorized access, tampering, or destruction by adversaries. By leveraging remote storage solutions, organizations enhance the protection of forensic evidence, sensitive information, and monitoring data.

Centralized Log Management
  • Configure endpoints to forward security logs to a centralized log collector or SIEM.
  • Use tools like Splunk Graylog, or Security Onion to aggregate and store logs.
  • Example command (Linux): sudo auditd | tee /var/log/audit/audit.log | nc <remote-log-server> 514 Remote File Storage Solutions:.
  • Utilize cloud storage solutions like AWS S3, Google Cloud Storage, or Azure Blob Storage for sensitive data.
  • Ensure proper encryption at rest and access control policies (IAM roles, ACLs).
Intrusion Detection Log Forwarding
  • Forward logs from IDS/IPS systems (e.g., Zeek/Suricata) to a remote security information system.
Example for Suricata log forwarding: `outputs
  • type: syslog protocol: tls address: <remote-syslog-server>` Immutable Backup Configurations:.
  • Enable immutable storage settings for backups to prevent adversaries from modifying or deleting data.
  • Example: AWS S3 Object Lock.
Data Encryption
  • Ensure encryption for sensitive data using AES-256 at rest and TLS 1.2+ for data in transit. Tools: OpenSSL, BitLocker, LUKS for Linux.
M1039Environment Variable Permissions

Restrict the modification of environment variables to authorized users and processes by enforcing strict permissions and policies. This ensures the integrity of environment variables, preventing adversaries from abusing or altering them for malicious purposes.

Restrict Write Access
  • Use Case: Set file system-level permissions to restrict access to environment variable configuration files (e.g., .bashrc, .bash_profile, .zshrc, systemd service files).
  • Implementation: Configure /etc/environment or /etc/profile on Linux systems to only allow root or administrators to modify the file.
Secure Access Controls
  • Use Case: Limit access to environment variable settings in application deployment tools or CI/CD pipelines to authorized personnel.
  • Implementation: Use role-based access control (RBAC) in tools like Jenkins or GitLab to ensure only specific users can modify environment variables.
Restrict Process Scope
  • Use Case: Configure policies to ensure environment variables are only accessible to the processes they are explicitly intended for.
  • Implementation: Use containerized environments like Docker to isolate environment variables to specific containers and ensure they are not inherited by other processes.
Audit Environment Variable Changes
  • Use Case: Enable logging for changes to critical environment variables.
  • Implementation: Use auditd on Linux to monitor changes to files like /etc/environment or application-specific environment files.
◈

Detection Coverage

2/6 layers
Coverage across standard detection surfaces. Rows marked none have no rule of that type mapped. Some are real blind spots worth closing; others are simply not applicable to this technique (e.g. YARA matches malware files, not network behaviour).
Behavioral / log (Sigma) 9
Analytics (MITRE CAR) 1
Runtime / container (Falco) none
File / malware (YARA) none
Network (Suricata/Snort) none
Vuln scan (Nuclei) none
◈

CAR Analytics

1
MITRE Cyber Analytics Repository - field-tested detection logic for this technique, written as pseudocode/queries you adapt to your own SIEM (Splunk, Sentinel, EQL). Each is a ready starting point for a detection rule, not just a description.
CAR-2020-11-005Low coverageClear Powershell Console Command History

Adversaries may attempt to conceal their tracks by deleting the history of commands run within the Powershell console, or turning off history saving to begin with. This analytic looks for several commands that would do this. This does not capture the event if it is done within the console itself.

only commandline-based commands are detected. Note that the command to remove the history file directly may very a bit if the history file is not saved in the default path on a particular system.

Pseudocode - Pseudocode - clear or disable Powershell console history via commandline
processes = search Process:Create
clear_commands = filter processes where (
  command_line ="*rm (Get-PSReadlineOption).HistorySavePath*" OR command_line="*del (Get-PSReadlineOption).HistorySavePath*" OR command_line="*Set-PSReadlineOption –HistorySaveStyle SaveNothing*" OR command_line="*Remove-Item (Get-PSReadlineOption).HistorySavePath*")  OR command_linee="del*Microsoft\Windows\Powershell\PSReadline\ConsoleHost_history.txt")
output clear_commands
Splunk - Splunk Search - clear command history via Powershell
(index=__your_sysmon_index__ EventCode=1) (CommandLine="*rm (Get-PSReadlineOption).HistorySavePath*" OR CommandLine="*del (Get-PSReadlineOption).HistorySavePath*" OR CommandLine="*Set-PSReadlineOption –HistorySaveStyle SaveNothing*" OR CommandLine="*Remove-Item (Get-PSReadlineOption).HistorySavePath*" OR CommandLine="del*Microsoft\\Windows\\Powershell\\PSReadline\\ConsoleHost_history.txt")
LogPoint - LogPoint Search - clear command history via Powershell
norm_id=WindowsSysmon event_id=1 (command="*rm (Get-PSReadlineOption).HistorySavePath*" OR command="*del (Get-PSReadlineOption).HistorySavePath*" OR command="*Set-PSReadlineOption –HistorySaveStyle SaveNothing*" OR command="*Remove-Item (Get-PSReadlineOption).HistorySavePath*" OR command="del*Microsoft\Windows\Powershell\PSReadline\ConsoleHost_history.txt")
▸

Caldera Emulation

1
MITRE Caldera abilities that emulate this technique - each is an executable action for automated adversary emulation.
defense-evasiondarwin, linux, windowsAvoid logs
> $HOME/.bash_history && unset HISTFILE
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Comply & Defend

NIST 800-53AC-02, AC-03, AC-05, AC-06, CA-07, CM-02, CM-06, SI-03, SI-04, SI-07
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