[ GLSA 201601-01 ] OpenSSH

[GLSA]

Gentoo Linux Security Advisory

Title: OpenSSH: Multiple vulnerabilities (GLSA 201601-01)
Severity: normal
Exploitable: remote
Date: January 16, 2016
Bug(s): #571892
ID: 201601-01

Synopsis

Multiple vulnerabilities have been found in OpenSSH, allowing
attackers to leak client memory to a server, including private keys.


Background

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


Affected Packages

Package: net-misc/openssh
Vulnerable: < 7.1_p2
Unaffected: >= 7.1_p2
Architectures: All supported architectures


Description

Qualys have reported two issues in the “roaming” code included in
the OpenSSH client, which provides undocumented, experimental support for
resuming SSH connections. An OpenSSH client could be tricked into leaking
parts of its memory to a malicious server. Furthermore, a buffer overflow
can be exploited by a malicious server, but its exploitation requires
non-default options and is mitigated due to another bug.


Impact

A remote attacker could entice a user to connect to a specially crafted
OpenSSH server, possibly resulting in the disclosure of the user’s
private keys. Users with private keys that are not protected by a
passphrase are advised to generate new keys if they have connected to an
SSH server they don’t fully trust.
Note that no special configuration is required to be vulnerable as the
roaming feature is enabled by default on the client.


Workaround

The issues can be worked around by disabling the roaming code. To do so,
add “UseRoaming no” to the SSH client configuration, or specify “-o
‘UseRoaming no’” on the command line.


Resolution

All OpenSSH users should upgrade to the latest version: