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-r1|
|Unaffected versions||>= 2.6-r1|
DenyHosts is designed to monitor SSH servers for repeated failed login attempts.
Daniel B. Cid discovered that DenyHosts used an incomplete regular expression to parse failed login attempts, a different issue than GLSA 200701-01.
A remote unauthenticated attacker can add arbitrary hosts into the blacklist, including the "all" keyword, by submitting specially crafted version identification strings to the SSH server banner. 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-r1"
October 13, 2007
October 13, 2007: 01