Bug 1216133 (CVE-2015-2694) - CVE-2015-2694 krb5: issues in OTP and PKINIT kdcpreauth modules leading to requires_preauth bypass
Summary: CVE-2015-2694 krb5: issues in OTP and PKINIT kdcpreauth modules leading to re...
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2015-2694
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1216134 1218020
Blocks: 1210268 1216136
TreeView+ depends on / blocked
 
Reported: 2015-04-28 14:46 UTC by Martin Prpič
Modified: 2021-02-17 05:20 UTC (History)
8 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
A flaw was found in the OTP kdcpreauth module of MIT Kerberos. A remote attacker could use this flaw to bypass the requires_preauth flag on a client principal and obtain a ciphertext encrypted in the principal's long-term key. This ciphertext could be used to conduct an off-line dictionary attack against the user's password.
Clone Of:
Environment:
Last Closed: 2015-11-20 05:43:50 UTC
Embargoed:

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System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2015:2154 0 normal SHIPPED_LIVE Moderate: krb5 security, bug fix, and enhancement update 2015-11-19 08:16:22 UTC

Description Martin Prpič 2015-04-28 14:46:49 UTC 
The following flaw was found in MIT Kerberos:

In the OTP kdcpreauth module, the TKT_FLG_PRE_AUTH bit was set before the request was successfully verified. In the PKINIT kdcpreauth module, code 0 was returned on empty input or an unconfigured realm. Together, these bugs could cause the KDC preauth framework to erroneously treat a request as pre-authenticated.

In MIT krb5 1.12 and later, when the KDC is configured with PKINIT support, an unauthenticated remote attacker can bypass the requires_preauth flag on a client principal and obtain a ciphertext encrypted in the principal's long-term key. This ciphertext could be used to conduct an off-line dictionary attack against the user's password.

Upstream patch:

https://github.com/krb5/krb5/commit/e3b5a5e5267818c97750b266df50b6a3d4649604
Comment 1 Martin Prpič 2015-04-28 14:47:38 UTC 
Created krb5 tracking bugs for this issue:

Affects: fedora-21 [bug 1216134]
Comment 3 Huzaifa S. Sidhpurwala 2015-05-04 03:38:29 UTC 
Statement:

This issue does not affect the version of krb5 package as shipped with Red Hat Enterprise Linux 5 and 6.
Comment 5 Fedora Update System 2015-05-11 19:02:49 UTC 
krb5-1.13.1-3.fc22 has been pushed to the Fedora 22 stable repository.  If problems still persist, please make note of it in this bug report.
Comment 6 Fedora Update System 2015-06-21 00:28:40 UTC 
krb5-1.12.2-17.fc21 has been pushed to the Fedora 21 stable repository.  If problems still persist, please make note of it in this bug report.
Comment 7 errata-xmlrpc 2015-11-19 05:13:33 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2015:2154 https://rhn.redhat.com/errata/RHSA-2015-2154.html
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