A password authentication vulnerability with SSH Secure Shell 3.0.0 could allow hackers to gain root access on Unix servers.
Because of weak password authentication to the SSHD2 daemon it's been discovered that accounts with password fields consisting of two or fewer characters can be compromised using any password, including an empty password. Only Unix systems are affected by the vulnerability, which could be exploited by hackers to take control of servers.
Systems using OpenSSH are not affected by the issue.
Some of the systems that include default two-character passwords (and thus might be vulnerable if the affected software is used) are Red Hat Linux 6.1 through 7.1, Solaris 2.6 through 2.8, HP-UX 10.20, HP-UX 11.00, Caldera Linux 2.4, and SuSE Linux 6.4 through 7.0. Solaris systems are particularly vulnerable to the exploit, which would be trivial for hackers to pull off on Sun servers running the affected software.
Those sites using SecurID token, Kerberos, certificates, Smart Cards, or host authentication are protected from the vulnerability providing the password authentication to the SSH daemon is disabled. Likewise OpenBSD, NetBSD and Tru64 servers are also believed to be immune from the effects of the bug.
SSH Secure Shell has released several workarounds and a corrected version, 3.0.1, which system administrators are encouraged to review. ®