RealTime IT News

CERT Issues Security Advisory

A leading computer security group is warning individuals who use computer running certain variants of the UNIX operating system that they could be susceptible to a TCP/IP hack.

The Computer Emergency Response Team Coordination Center, or CERT, warned earlier this week that certain versions of the Free BSD and Berkeley Software Design version of UNIX are vulnerable.

CERT said intruders who construct a sequence of packets with certain characteristics can cause vulnerable systems to crash, hang or behave unpredictably. CERT did not detail the characteristics necessary for the attacks to be successful. The organization said the attack has similar effects to other well-known denial-of-service vulnerabilities.

The organization urged network administrators using the affected systems to configure their routers or firewalls to reduce hackers' ability to spoof source addresses.

"Currently, the best method to reduce the number of IP-spoofed packets exiting your network is to install filtering on your routers that require packets leaving your network to have a source address from your internal network. This type of filter prevents a source IP-spoofing attack from your site by filtering all outgoing packets that contain a source address of a different network," CERT's advisory said.

A detailed list of vendors whose products are affected is available here.