T1037.001_logon-script-windows

T1037.001 Logon Script (Windows)

Sub-technique of: T1037

High-Level Description

Adversaries may use Windows logon scripts automatically executed at logon initialization to establish persistence. Windows allows logon scripts to be run whenever a specific user or group of users log into a system. This is done via adding a path to a script to the HKCU\Environment\UserInitMprLogonScript Registry key.

Adversaries may use these scripts to maintain persistence on a single system. Depending on the access configuration of the logon scripts, either local credentials or an administrator account may be necessary.

Kill Chain Phase

• Persistence (TA0003)
• Privilege Escalation (TA0004)

Platforms: Windows

What to Check

• Identify if Logon Script (Windows) technique is applicable to target environment
• Check Windows systems for indicators of Logon Script (Windows)
• Verify mitigations are bypassed or absent (1 known mitigations)
• Assess detection coverage (1 detection strategies)

How to Test

Atomic Red Team Tests

The following tests are from Atomic Red Team and provide actionable ways to test this technique:

Atomic Test 1: Logon Scripts

Adds a registry value to run batch script created in the %temp% directory. Upon execution, there will be a new environment variable in the HKCU\Environment key that can be viewed in the Registry Editor.

Supported Platforms: windows

echo "#{script_command}" > #{script_path}
REG.exe ADD HKCU\Environment /v UserInitMprLogonScript /t REG_SZ /d "#{script_path}" /f

Manual Testing

If Atomic Red Team tests are not applicable, manually verify the technique by:

1. Identify Attack Surface: Determine if the target environment is susceptible to Logon Script (Windows) by examining the target platforms (Windows).

2. Assess Existing Defenses: Review whether mitigations for T1037.001 are in place. If defenses are absent or misconfigured, this technique may be exploitable.

3. Execute Test: Use tools and methods described in the MITRE ATT&CK page and external references below.

Remediation Guide

M1024 Restrict Registry Permissions

Ensure proper permissions are set for Registry hives to prevent users from modifying keys for logon scripts that may lead to persistence.

Detection

Detect Logon Script Modifications and Execution

Risk Assessment

CWE Categories

References

• Hexacorn Logon Scripts
• TechNet Logon Scripts
• Atomic Red Team - T1037.001
• MITRE ATT&CK - T1037.001