OpenSSH Race Condition in Signal Handler Lets Remote Users Deny Service and May Potentially Permit Code Execution
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SecurityTracker Alert ID: 1016940
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SecurityTracker URL: http://securitytracker.com/id?1016940
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CVE Reference: CVE-2006-5051
(Links to External Site)
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Date: Sep 28 2006
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Impact: Denial of service via network, Execution of arbitrary code via network, User access via network
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Fix Available: Yes
Vendor Confirmed: Yes
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Version(s): 4.3 and prior versions
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Description: A vulnerability was reported in OpenSSH. A remote user can cause denial of service conditions. A remote user may be able to execute arbitrary code on the target system.
A remote user can exploit a race condition in an unsafe signal hander to cause denial of service conditions.
On portable OpenSSH,
a remote user may theoretically be able to exploit this flaw to execute arbitrary code if GSSAPI authentication is enabled.
The
vendor credits Mark Dowd with reporting this vulnerability.
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Impact: A remote user can cause denial of service conditions.
A remote user may be able to execute arbitrary code on the target system.
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Solution: The vendor has issued a fixed version (4.4).
The OpenSSH advisory is available at:
http://www.openssh.org/txt/release-4.4
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Vendor URL: www.openssh.org/txt/release-4.4 (Links to External Site)
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Cause: State error
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Underlying OS: Linux (Any), UNIX (Any)
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Message History:
This archive entry has one or more follow-up message(s) listed below.
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Source Message Contents
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Date: Wed, 27 Sep 2006 22:27:26 -0400
Subject: OpenSSH vulnerability
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http://www.openssh.org/txt/release-4.4
* Fix an unsafe signal hander reported by Mark Dowd. The signal
handler was vulnerable to a race condition that could be exploited
to perform a pre-authentication denial of service. On portable
OpenSSH, this vulnerability could theoretically lead to
pre-authentication remote code execution if GSSAPI authentication
is enabled, but the likelihood of successful exploitation appears
remote.
CVE-2006-5051
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