Bug 1238238

Summary:	openssh: weakness of agent locking (ssh-add -x) to password guessing
Product:	[Other] Security Response	Reporter:	Vasyl Kaigorodov <vkaigoro>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	carnil, huzaifas, jjelen, mattias.ellert, mgrepl, plautrba, security-response-team, szidek, tmraz
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	OpenSSH 6.9	Doc Type:	Bug Fix
Doc Text:	It was found that the OpenSSH ssh-agent, a program to hold private keys used for public key authentication, was vulnerable to password guessing attacks. An attacker able to connect to the agent could use this flaw to conduct a brute-force attack to unlock keys in the ssh-agent.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-05-11 08:09:54 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1238241, 1247864, 1281468
Bug Blocks:	1252864

Description Vasyl Kaigorodov 2015-07-01 12:55:56 UTC

OpenSSH version 6.9 fix weakness of agent locking (ssh-add -x) to password guessing by implementing an increasing failure delay, storing a salted hash of the password rather than the password itself and using a timing-safe comparison function for verifying unlock attempts. This problem was reported by Ryan Castellucci.
Upstream patch: https://anongit.mindrot.org/openssh.git/commit/?h=V_6_9&id=9173d0fbe44de7ebcad8a15618e13a8b8d78902e

External References:

http://www.openssh.com/txt/release-6.9

Comment 1 Vasyl Kaigorodov 2015-07-01 12:59:26 UTC

Created openssh tracking bugs for this issue:

Affects: fedora-all [bug 1238241]

Comment 2 Martin Prpič 2015-07-02 12:20:57 UTC

Per http://openwall.com/lists/oss-security/2015/07/01/10 , MITRE did not assign a CVE to this issue:

"Our current thought is that a CVE ID may not be needed because attacks against ssh-agent locking don't cross a privilege boundary. In other words, the changelog entry could be interpreted to mean addition of a new security feature related to a threat model that wasn't in the previous design goals (e.g., password guessing by malware running under the same account)."

Comment 3 Fedora Update System 2015-07-10 19:09:15 UTC

openssh-6.6.1p1-13.fc21 has been pushed to the Fedora 21 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 4 Fedora Update System 2015-07-10 19:18:17 UTC

openssh-6.9p1-1.fc22 has been pushed to the Fedora 22 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 12 errata-xmlrpc 2015-11-19 08:03:45 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2015:2088 https://rhn.redhat.com/errata/RHSA-2015-2088.html