Fail2ban: Denial of Service

1.  Gentoo Linux Security Advisory

Version Information

Related bugreports: #181214

Synopsis

Fail2ban is vulnerable to a Denial of Service attack.

2.  Impact Information

Background

Fail2ban is a tool for parsing log files and banning IP addresses which make too many password failures.

Description

A vulnerability has been discovered in Fail2ban when parsing log files.

Impact

A remote attacker could send specially crafted SSH login banners to the vulnerable host, which would prevent any ssh connection to the host and result in a Denial of Service.

3.  Resolution Information

Workaround

There is no known workaround at this time.

Resolution

All Fail2ban users should upgrade to the latest version:

# emerge --sync
# emerge --ask --oneshot --verbose ">=net-analyzer/fail2ban-0.8.0-r1"

4.  References

• CVE-2007-4321
• Original advisory