Joined: 12 May 2004
|Posted: Wed Jan 03, 2007 7:26 pm Post subject: [ GLSA 200701-01 ] DenyHosts: Denial of Service
|Gentoo Linux Security Advisory
Title: DenyHosts: Denial of Service (GLSA 200701-01)
Date: January 03, 2007
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 attempts.
Vulnerable: < 2.6
Unaffected: >= 2.6
Architectures: All supported architectures
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"