OpenSSH: Privilege escalation

Security Team Contact Address

Updated April 05, 2008

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200804-03 / openssh
Release Date	April 05, 2008
Latest Revision	April 05, 2008: 01
Impact	normal
Exploitable	local

Package	Vulnerable versions	Unaffected versions	Architecture(s)
net-misc/openssh	< 4.7_p1-r6	>= 4.7_p1-r6	All supported architectures

Related bugreports: #214985, #215702

Synopsis

Two flaws have been discovered in OpenSSH which could allow local attackers to escalate their privileges.

2. Impact Information

Background

OpenSSH is a complete SSH protocol implementation that includes an SFTP client and server support.

Description

Two issues have been discovered in OpenSSH:

Timo Juhani Lindfors discovered that OpenSSH sets the DISPLAY variable in SSH sessions using X11 forwarding even when it cannot bind the X11 server to a local port in all address families (CVE-2008-1483).
OpenSSH will execute the contents of the ".ssh/rc" file even when the "ForceCommand" directive is enabled in the global sshd_config (CVE-2008-1657).

Impact

A local attacker could exploit the first vulnerability to hijack forwarded X11 sessions of other users and possibly execute code with their privileges, disclose sensitive data or cause a Denial of Service, by binding a local X11 server to a port using only one address family. The second vulnerability might allow local attackers to bypass intended security restrictions and execute commands other than those specified by "ForceCommand" if they are able to write to their home directory.

3. Resolution Information

Workaround

There is no known workaround at this time.

Resolution

All OpenSSH users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=net-misc/openssh-4.7_p1-r6"

4. References