Ubuntu Security Notice USN-612-5
14th May, 2008
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 8.04 LTS
- Ubuntu 7.10
- Ubuntu 7.04
Matt Zimmerman discovered that entries in ~/.ssh/authorized_keys
with options (such as "no-port-forwarding" or forced commands) were
ignored by the new ssh-vulnkey tool introduced in OpenSSH (see
USN-612-2). This could cause some compromised keys not to be
listed in ssh-vulnkey's output.
This update also adds more information to ssh-vulnkey's manual page.
Original advisory details:
A weakness has been discovered in the random number generator used
by OpenSSL on Debian and Ubuntu systems. As a result of this
weakness, certain encryption keys are much more common than they
should be, such that an attacker could guess the key through a
brute-force attack given minimal knowledge of the system. This
particularly affects the use of encryption keys in OpenSSH, OpenVPN
and SSL certificates.
The problem can be corrected by updating your system to the following package version:
- Ubuntu 8.04 LTS:
- openssh-client 1:4.7p1-8ubuntu1.2
- openssh-client-udeb 1:4.7p1-8ubuntu1.2
- Ubuntu 7.10:
- openssh-client 1:4.6p1-5ubuntu0.5
- openssh-client-udeb 1:4.6p1-5ubuntu0.5
- Ubuntu 7.04:
- openssh-client 1:4.3p2-8ubuntu1.4
- openssh-client-udeb 1:4.3p2-8ubuntu1.4
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
After performing a standard system upgrade, users are encouraged to
re-run ssh-vulnkey on their systems.