By Joris Evers
Staff Writer, CNET News.com
March 14, 2007
A vulnerability in the way OpenBSD handles IPv6 data packets exposes
systems running the traditionally secure open-source operating system to
A memory corruption vulnerability error exists in the OpenBSD code that
handles IPv6 packets, Core Security Technologies said in an alert
published Tuesday. Exploiting the flaw could let an attacker commandeer
a vulnerable system, according to Core, which said it discovered the
issue and crafted sample exploit code.
"This vulnerability allows attackers to gain complete control of the
target system, bypassing all the operating system's security
mechanisms," Core said in a statement Wednesday. Core deems the issue
"critical." Security-monitoring company Secunia rates it "highly
OpenBSD is one of several operating systems based on the Berkeley
Software Distribution, or BSD. The most popular BSD descendents are
FreeBSD, PCBSD and NetBSD, with OpenBSD coming in fourth, according to
the BSDstats project.
OpenBSD is mostly known for its security enhancements and is used for
firewalls, intrusion detection systems and other applications. Google is
among OpenBSD users and backers. The OpenBSD team likes to tout that
only a few remotely exploitable vulnerabilities have been found in the
code in a decade.
A security update was issued last week to deal with the OpenBSD issue,
which affects multiple releases of the operating system.
Default installations of OpenBSD are vulnerable as IPv6 is enabled and
the system does not filter inbound packets, Core said. IPv6 is the next
version of the Internet Protocol designed to support a broader range of
IP addresses as the IP version 4 addresses currently in use become more
To exploit the vulnerability, an attacker must have the ability to send
malicious IPv6 packets to the target system or be on the same network,
Symantec said in an alert. The Cupertino, Calif., security company
raised its ThreatCon to level 2 because of the issue, which means
attacks are expected.
As a work-around for users who can not apply the OpenBSD patch or who do
not need to process or route IPv6 traffic on their systems, all inbound
IPv6 packets can be blocked by using Openness' firewall.
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