DenyHosts: Denial of Service
Gentoo Linux Security Advisory
||GLSA 200701-01 / denyhosts
||January 03, 2007
||January 03, 2007: 01
All supported architectures
DenyHosts does not correctly parse log entries, potentially causing a
remote Denial of Service.
DenyHosts is designed to monitor SSH servers for repeated failed login
Tavis Ormandy of the Gentoo Linux Security Audit Team discovered that
DenyHosts used an incomplete regular expression to parse failed login
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
There is no known workaround at this time.
All DenyHosts users should upgrade to the latest version:
Code Listing 3.1: Resolution
# emerge --sync
# emerge --ask --oneshot --verbose ">=app-admin/denyhosts-2.6"