DenyHosts does not correctly parse log entries, potentially causing a remote Denial of Service.
|Package||app-admin/denyhosts on all architectures|
|Affected versions||< 2.6|
|Unaffected versions||>= 2.6|
DenyHosts is designed to monitor SSH servers for repeated failed login attempts.
Tavis Ormandy of the Gentoo Linux Security Audit Team discovered that DenyHosts used an incomplete regular expression to parse failed login attempts.
A remote unauthenticated attacker can add arbitrary hosts to the blacklist by attempting to login with a specially crafted username. An attacker may use this to prevent legitimate users from accessing a host remotely.
There is no known workaround at this time.
All DenyHosts users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=app-admin/denyhosts-2.6"
January 03, 2007
January 03, 2007: 01