T1216 System Script Proxy Execution — Attack Pattern

Description

Adversaries may use trusted scripts, often signed with certificates, to proxy the execution of malicious files. Several Microsoft signed scripts that have been downloaded from Microsoft or are default on Windows installations can be used to proxy execution of other files.(Citation: LOLBAS Project) This behavior may be abused by adversaries to execute malicious files that could bypass application control and signature validation on systems.(Citation: GitHub Ultimate AppLocker Bypass List)

MITRE ATT&CK Detection Strategies
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DET0466 Detection of Script-Based Proxy Execution via Signed Microsoft Utilities

AN1288 Windows

Execution of Microsoft-signed scripts (e.g., pubprn.vbs, installutil.exe, wscript.exe, cscript.exe) used to proxy execution of untrusted or external binaries. Behavior is detected through command-line process lineage, child process spawning, and unsigned payload execution from signed parent.

WinEventLog:Sysmon WinEventLog:PowerShell WinEventLog:Sysmon WinEventLog:Sysmon WinEventLog:Sysmon

MITRE ATT&CK Mitigations
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M1038

Execution Prevention

Prevent the execution of unauthorized or malicious code on systems by implementing application control, script blocking, and other execution prevention mechanisms. This ensures that only trusted and authorized code is executed, reducing the risk of malware and unauthorized actions. This mitigation can be implemented through the following measures: Application Control: - Use Case: Use tools like AppLocker or Windows Defender Application Control (WDAC) to create whitelists of authorized applications and block unauthorized ones. On Linux, use tools like SELinux or AppArmor to define mandatory access control policies for application execution. - Implementation: Allow only digitally signed or pre-approved applications to execute on servers and endpoints. (e.g., `New-AppLockerPolicy -PolicyType Enforced -FilePath "C:\Policies\AppLocker.xml"`) Script Blocking: - Use Case: Use script control mechanisms to block unauthorized execution of scripts, such as PowerShell or JavaScript. Web Browsers: Use browser extensions or settings to block JavaScript execution from untrusted sources. - Implementation: Configure PowerShell to enforce Constrained Language Mode for non-administrator users. (e.g., `Set-ExecutionPolicy AllSigned`) Executable Blocking: - Use Case: Prevent execution of binaries from suspicious locations, such as `%TEMP%` or `%APPDATA%` directories. - Implementation: Block execution of `.exe`, `.bat`, or `.ps1` files from user-writable directories. Dynamic Analysis Prevention: - Use Case: Use behavior-based execution prevention tools to identify and block malicious activity in real time. - Implemenation: Employ EDR solutions that analyze runtime behavior and block suspicious code execution.

System Script Proxy Execution

Description

MITRE ATT&CK Detection Strategies 1

MITRE ATT&CK Mitigations 1

Details

MITRE ATT&CK Detection Strategies
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MITRE ATT&CK Mitigations
1