Microsoft Windows Kerberos Key Distribution Center (KDC) fails to properly validate Privilege Attribute Certificate (PAC) signature

Overview

Microsoft Windows Kerberos KDC contains a vulnerability allowing an authenticated unprivileged domain user to escalate privileges to a domain administrator account, allowing the user to compromise any computer on the domain.

Description

CWE-347: Improper Verification of Cryptographic Signature

The Microsoft Windows Kerberos KDC fails to properly check for valid signatures in the Privilege Attribute Certificate (PAC) included with the Kerberos ticket request. A domain user may forge the information contained in the PAC to request higher user privileges than should be allowed. Since the KDC does not verify the signature correctly, it will award the user the requested privileges, effectively making the user a domain administrator and allowing complete compromise of the entire domain.

The Microsoft Research Security and Defense Blog has a more technical description of the vulnerability.

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Impact

An unprivileged domain user may escalate to domain administrator privileges, allowing the user to fully compromise any computer on the domain, including the domain controller.

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Solution

Apply an update

Microsoft has released an update addressing this vulnerability. Please see Microsoft Security Bulletin MS14-068 for more information.

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Vendor Information

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Microsoft Corporation Affected

Updated: November 18, 2014

Status

Affected

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

We are not aware of further vendor information regarding this vulnerability.

Vendor References

• <https://technet.microsoft.com/library/security/MS14-068&gt;

CVSS Metrics

Group	Score	Vector
Base	9	AV:N/AC:L/Au:S/C:C/I:C/A:C
Temporal	7.4	E:F/RL:OF/RC:C
Environmental	8.5	CDP:MH/TD:H/CR:ND/IR:ND/AR:ND

References

• <https://technet.microsoft.com/library/security/MS14-068&gt;
• <http://blogs.technet.com/b/srd/archive/2014/11/18/additional-information-about-cve-2014-6324.aspx&gt;
• <http://msdn.microsoft.com/en-us/library/cc237955.aspx&gt;

Acknowledgements

Microsoft credits the Qualcomm Information Security & Risk Management team, with special recognition for Tom Maddock.

This document was written by Garret Wassermann.

Other Information

CVE IDs:	CVE-2014-6324
Date Public:	2014-11-18 Date First Published: