1. Ubuntu Security Notices
  2. USN-34-1

USN-34-1: OpenSSH information leakage

Publication date

30 November 2004

Overview

OpenSSH information leakage

Releases

Details

@Mediaservice.net discovered two information leaks in the OpenSSH
server. When using password authentication, an attacker could
test whether a login name exists by measuring the time between
failed login attempts, i. e. the time after which the “password:”
prompt appears again.

A similar issue affects systems which do not allow root logins over
ssh (“PermitRootLogin no”). By measuring the time between login
attempts an attacker could check whether a given root password is
correct. This allowed determining weak root passwords using a brute
force attack.

@Mediaservice.net discovered two information leaks in the OpenSSH
server. When using password authentication, an attacker could
test whether a login name exists by measuring the time between
failed login attempts, i. e. the time after which the “password:”
prompt appears again.

A similar issue affects systems which do not allow root logins over
ssh (“PermitRootLogin no”). By measuring the time between login
attempts an attacker could check whether a given root password is
correct. This allowed determining weak root passwords using a brute
force attack.

Update instructions

In general, a standard system update will make all the necessary changes.

Learn more about how to get the fixes.

The problem can be corrected by updating your system to the following package versions:

Ubuntu Release Package Version
4.10 warty openssh-server – 

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References

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