OpenSSH GSSAPI user enumeration

openssh-gssapi-user-enumeration (29255)

Low Risk

Description:

OpenSSH portable version could allow a remote attacker to determine valid usernames. The GSSAPI authentication abort returns different error messages depending on whether a valid username has been entered during a login attempt. An attacker could use this information to enumerate valid usernames.

*CVSS:

Base Score:	3.5
Access Vector:	Remote
Access Complexity:	Low
Authentication:	Not Required
Confidentiality Impact:	Partial
Integrity Impact:	None
Availability Impact:	None
Temporal Score:	2.6
Exploitability:	Unproven
Remediation Level:	Official-Fix
Report Confidence:	Confirmed

Consequences:

Obtain Information

Remedy:

Upgrade to the latest version of Mac OS X (10.4.9 or later) or apply Apple Security Update 2007-003. See References.

Upgrade to the latest version of OpenSSH (4.4 or later), available from the OpenSSH Web site. See References.

For SUSE Linux:
Refer to SUSE-SA:2006:062 for patch, upgrade, or suggested workaround information. See References.

References:

• Apple Mac OS X Web site: Apple - Apple - Mac OS X - Leopard Sneak Peek.
• BugTraq Mailing List, Mon Oct 09 2006 - 05:33:05 CDT: yet another OpenSSH timing leak?.
• Mac OS X 10.4.9 and Security Update 2007-003: About the security content of Mac OS X 10.4.9 and Security Update 2007-003.
• OpenSSH Web site: OpenSSH.
• openssh-unix-dev Mailing List, 2006-09-27 21:08:47: Announce: OpenSSH 4.4 released.
• ASA-2007-527: OpenSSH security and bug fix update (RHSA-2007-0703)
• BID-20245: OpenSSH-Portable GSSAPI Authentication Abort Information Disclosure Weakness
• CVE-2006-5052: Unspecified vulnerability in portable OpenSSH before 4.4, when running on some platforms, allows remote attackers to determine the validity of usernames via unknown vectors involving a GSSAPI authentication abort.
• GLSA-200611-06: OpenSSH: Multiple Denial of Service vulnerabilities
• OSVDB ID: 29266: OpenSSH GSSAPI Authentication Abort Username Enumeration
• RHSA-2007-0540: Moderate: openssh security and bug fix update
• RHSA-2007-0703: Moderate: openssh security and bug fix update
• SA22173: OpenSSH Signal Handling Vulnerability
• SA24479: Mac OS X Security Update Fixes Multiple Vulnerabilities
• SA28320: Avaya Products openssh Multiple Vulnerabilities
• SECTRACK ID: 1016939: OpenSSH GSSAPI Authentication Abort Error Lets Remote Users Determine Valid Usernames
• SUSE-SA:2006:062: openssh security update

Platforms Affected:

• Gentoo Linux
• Novell Linux Desktop 9
• Novell Linux POS 9
• Novell Open Enterprise Server
• Novell Open Enterprise Server
• Novell UnitedLinux 1.0
• OpenBSD OpenSSH 1.2
• OpenBSD OpenSSH 1.2.1
• OpenBSD OpenSSH 1.2.2
• OpenBSD OpenSSH 1.2.27
• OpenBSD OpenSSH 1.2.3
• OpenBSD OpenSSH 2.1
• OpenBSD OpenSSH 2.1.1
• OpenBSD OpenSSH 2.1.1p4
• OpenBSD OpenSSH 2.2
• OpenBSD OpenSSH 2.2.0p1
• OpenBSD OpenSSH 2.3
• OpenBSD OpenSSH 2.3.0p1
• OpenBSD OpenSSH 2.5
• OpenBSD OpenSSH 2.5.1
• OpenBSD OpenSSH 2.5.1p1
• OpenBSD OpenSSH 2.5.1p2
• OpenBSD OpenSSH 2.5.2
• OpenBSD OpenSSH 2.5.2p1
• OpenBSD OpenSSH 2.5.2p2
• OpenBSD OpenSSH 2.9
• OpenBSD OpenSSH 2.9.9
• OpenBSD OpenSSH 2.9.9p1
• OpenBSD OpenSSH 2.9.9p2
• OpenBSD OpenSSH 2.9p1
• OpenBSD OpenSSH 2.9p2
• OpenBSD OpenSSH 3.0
• OpenBSD OpenSSH 3.0.1
• OpenBSD OpenSSH 3.0.1p1
• OpenBSD OpenSSH 3.0.2
• OpenBSD OpenSSH 3.0.2p1
• OpenBSD OpenSSH 3.0p1
• OpenBSD OpenSSH 3.1
• OpenBSD OpenSSH 3.1p1
• OpenBSD OpenSSH 3.2
• OpenBSD OpenSSH 3.2.2
• OpenBSD OpenSSH 3.2.2p1
• OpenBSD OpenSSH 3.2.3
• OpenBSD OpenSSH 3.2.3p1
• OpenBSD OpenSSH 3.3
• OpenBSD OpenSSH 3.3p1
• OpenBSD OpenSSH 3.4
• OpenBSD OpenSSH 3.4p1
• OpenBSD OpenSSH 3.5
• OpenBSD OpenSSH 3.5p1
• OpenBSD OpenSSH 3.6
• OpenBSD OpenSSH 3.6.1
• OpenBSD OpenSSH 3.6.1p1
• OpenBSD OpenSSH 3.6.1p2
• OpenBSD OpenSSH 3.7
• OpenBSD OpenSSH 3.7.1
• OpenBSD OpenSSH 3.7.1p1
• OpenBSD OpenSSH 3.7.1p2
• OpenBSD OpenSSH 3.8
• OpenBSD OpenSSH 3.8.1
• OpenBSD OpenSSH 3.8.1p1
• OpenBSD OpenSSH 3.9
• OpenBSD OpenSSH 3.9.1
• OpenBSD OpenSSH 3.9.1p1
• OpenBSD OpenSSH 4.0
• OpenBSD OpenSSH 4.0p1
• OpenBSD OpenSSH 4.1
• OpenBSD OpenSSH 4.1p1
• OpenBSD OpenSSH 4.2
• OpenBSD OpenSSH 4.2p1
• OpenBSD OpenSSH 4.3
• OpenBSD OpenSSH 4.3p1
• OpenBSD OpenSSH 4.3p2
• RedHat Enterprise Linux 4 Desktop
• RedHat Enterprise Linux 4 WS
• RedHat Enterprise Linux 4 ES
• RedHat Enterprise Linux 4 AS
• RedHat Enterprise Linux 5 Client
• RedHat Enterprise Linux 5
• SuSE Linux Enterprise Server 8
• SUSE SuSE Linux 10.0
• SUSE SuSE Linux 10.1
• SUSE SuSE Linux 9.2
• SUSE SuSE Linux 9.3
• SuSE SuSE Linux Desktop 1.0
• SuSE SuSE Linux OpenExchange Server 4
• SuSE SuSE Linux Retail Solution 8
• SuSE SuSE Linux School Server
• SuSE SuSE Linux Standard Server 8
• SuSE SuSE SLED 10
• SuSE SuSE SLES 10
• SuSE SuSE SLES 9
• Turbolinux Turbolinux 10 Server
• Turbolinux Turbolinux 10 Server x64 Ed
• Turbolinux Turbolinux FUJI
• Turbolinux Turbolinux Appliance Server 2.0

Reported:

Sep 27, 2006

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For corrections or additions please email xforce@iss.net

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