OpenSSH portable 4.1 on SUSE Linux, and possibly other platforms and versions, and possibly under limited configurations, allows remote attackers to determine valid usernames via timing discrepancies in which responses take longer for valid usernames than invalid ones, as demonstrated by sshtime. NOTE: as of 20061014, it appears that this issue is dependent on the use of manually-set passwords that causes delays when processing /etc/shadow due to an increased number of rounds.
secunia.com/advisories/25979
www.osvdb.org/32721
www.securityfocus.com/archive/1/448025/100/0/threaded
www.securityfocus.com/archive/1/448108/100/0/threaded
www.securityfocus.com/archive/1/448156/100/0/threaded
www.securityfocus.com/archive/1/448702/100/0/threaded
www.securityfocus.com/bid/20418
www.sybsecurity.com/hack-proventia-1.pdf
www.vupen.com/english/advisories/2007/2545