Avahi: Denial of Service

Security Team  Contact Address

Updated April 08, 2009

1.  Gentoo Linux Security Advisory

Version Information

Advisory Reference GLSA 200904-10 / avahi
Release Date April 08, 2009
Latest Revision April 08, 2009: 01
Impact normal
Exploitable remote
Package Vulnerable versions Unaffected versions Architecture(s)
net-dns/avahi < 0.6.24-r2 >= 0.6.24-r2 All supported architectures

Related bugreports: #260971

Synopsis

An error in Avahi might lead to a Denial of Service via network and CPU consumption.

2.  Impact Information

Background

Avahi is a system that facilitates service discovery on a local network.

Description

Rob Leslie reported that the originates_from_local_legacy_unicast_socket() function in avahi-core/server.c does not account for the network byte order of a port number when processing incoming multicast packets, leading to a multicast packet storm.

Impact

A remote attacker could send specially crafted legacy unicast mDNS query packets to the Avahi daemon, resulting in a Denial of Service due to network bandwidth and CPU consumption.

3.  Resolution Information

Workaround

There is no known workaround at this time.

Resolution

All Avahi users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=net-dns/avahi-0.6.24-r2"

4.  References