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Bug 2165827 - CVE-2022-37967: MS-PAC extended KDC signature [rhel-9]
Summary: CVE-2022-37967: MS-PAC extended KDC signature [rhel-9]
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: krb5
Version: 9.2
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Julien Rische
QA Contact: Filip Dvorak
Filip Hanzelka
URL:
Whiteboard:
Depends On:
Blocks: 2166001 2169477 2182135
TreeView+ depends on / blocked
 
Reported: 2023-01-31 08:49 UTC by Julien Rische
Modified: 2023-11-20 11:57 UTC (History)
3 users (show)

Fixed In Version: krb5-1.20.1-6.el9
Doc Type: Enhancement
Doc Text:
.MIT Kerberos supports the Ticket and Extended KDC MS-PAC signatures With this update, MIT Kerberos, which is used by Red Hat, implements support for two types of the Privilege Attribute Certificate (PAC) signatures introduced by Microsoft in response to recent CVEs. Specifically, the following signatures are supported: * Ticket signature ** Released in link:https://support.microsoft.com/en-au/topic/kb4598347-managing-deployment-of-kerberos-s4u-changes-for-cve-2020-17049-569d60b7-3267-e2b0-7d9b-e46d770332ab[KB4598347] ** Addressing link:https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2020-17049[CVE-2020-17049], also known as the "Bronze-Bit" attack * Extended KDC signature ** Released in link:https://support.microsoft.com/en-us/topic/kb5020805-how-to-manage-kerberos-protocol-changes-related-to-cve-2022-37967-997e9acc-67c5-48e1-8d0d-190269bf4efb[KB5020805] ** Addressing link:https://msrc.microsoft.com/update-guide/vulnerability/CVE-2022-37967[CVE-2022-37967] See also link:https://access.redhat.com/errata/RHSA-2023:2570[RHSA-2023:2570] and `krb5-1.20.1-6.el9`.
Clone Of:
: 2166001 2169477 (view as bug list)
Environment:
Last Closed: 2023-05-09 08:25:24 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Github krb5 krb5 pull 1284 0 None Merged Add PAC full signatures 2023-01-31 08:50:36 UTC
Red Hat Issue Tracker FREEIPA-9388 0 None None None 2023-01-31 08:53:55 UTC
Red Hat Issue Tracker RHELPLAN-147006 0 None None None 2023-01-31 08:54:01 UTC
Red Hat Product Errata RHSA-2023:2570 0 None None None 2023-05-09 08:26:08 UTC

Description Julien Rische 2023-01-31 08:49:07 UTC 
A paper by Tom Tervoort[1] noted that computing the PAC privsvr checksum over only the server checksum is vulnerable to collision attacks. In response, Microsoft has added a second KDC checksum over the full contents of the PAC[2].

This change will be required for PAC signatures to be accepted by AD from the 2023-07-11[3].

[1] https://i.blackhat.com/EU-22/Thursday-Briefings/EU-22-Tervoort-Breaking-Kerberos-RC4-Cipher-and-Spoofing-Windows-PACs-wp.pdf
[2] https://winprotocoldoc.blob.core.windows.net/productionwindowsarchives/MS-PAC/%5bMS-PAC%5d-20221212-diff.pdf
[3] https://support.microsoft.com/en-us/topic/kb5020805-how-to-manage-kerberos-protocol-changes-related-to-cve-2022-37967-997e9acc-67c5-48e1-8d0d-190269bf4efb
Comment 1 Julien Rische 2023-01-31 08:50:37 UTC 
The fix is available upstream:
https://github.com/krb5/krb5/pull/1284
Comment 9 errata-xmlrpc 2023-05-09 08:25:24 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (Moderate: krb5 security, bug fix, and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2023:2570
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