Bug 755640 (CVE-2011-4327)

Summary:	CVE-2011-4327 openssh: Unauthorized local access to host keys on platforms where ssh-rand-helper used
Product:	[Other] Security Response	Reporter:	Jan Lieskovsky <jlieskov>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	592028873, hui.zhu, jchadima, mattias.ellert, mgrepl, plautrba, tmraz
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
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Clone Of:		Environment:
Last Closed:	2011-11-21 17:21:49 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Jan Lieskovsky 2011-11-21 16:53:18 UTC

A security flaw was found in the way ssh-keysign, a ssh helper program for host based authentication, attempted to retrieve enough entropy information on configurations that lacked a built-in entropy pool in OpenSSL (a ssh-rand-helper program would be executed to retrieve the entropy from the system environment). A local attacker could use this flaw to obtain unauthorized access to host keys via ptrace(2) process trace attached to the 'ssh-rand-helper' program.

References:
[1] http://www.openssh.com/txt/release-5.8p2
[2] http://www.openssh.com/txt/portable-keysign-rand-helper.adv
[3] http://www.nessus.org/plugins/index.php?view=single&id=53841
[4] http://www.openwall.com/lists/oss-security/2011/11/21/11
    (CVE assignment)

Comment 1 Jan Lieskovsky 2011-11-21 17:06:08 UTC

This issue did NOT affect the versions of the openssh package, as shipped with Red Hat Enterprise Linux 4, 5, and 6, since these versions use a built-in entropy pool to generate and retrieve entropy information by performing host-based authentication.

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This issue did NOT affect the versions of the openssh package, as shipped with Fedora release of 14, 15, and 16, since these versions use a built-in entropy pool to generate and retrieve entropy information by performing host-based authentication.

Comment 2 Jan Lieskovsky 2011-11-21 17:21:49 UTC

Statement:

Not vulnerable. This issue did not affect the versions of openssh as shipped with Red Hat Enterprise Linux 4, 5, and 6, as they use a built-in entropy pool to generate and retrieve entropy information when performing host-based authentication.