Users are warned to be vigilant after trojanised versions of popular packet sniffing packages were posted on well known download sites.

A detailed alert from members of the Houston Linux users group warns that trojanised versions of Libpcap, used as a packet sniffing library in programs like Snort (the open source IDS package), and Tcpdump have been posted on Tcpdump.org. These contaminated packages have also found their way onto many mirror sites, such as Wiretapped.net
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The trojan contains modifications to the configure script for both packages. It also alters gencode.c in libpcap only.

Russ Spooner, of network security specialists Interrorem, told us that the warning is genuine and affects a wide range of widely used programmes.

"Libpcap is massively used across a wide range of platforms, programs such as ethereal use it, and of course tcpdump," he told us. "If Snort (one of the best IDS out there) is built against a trojanised lipcap, then obviously that would become vulnerable too".

"Even "hacking" tools like ettercap would be vulnerable to compromise with this, he added.

There is an important mitigating factor, however.

The backdoor component of the trojan tries to connect to a specific host (mars.raketti.net), and as such fail to open compromised systems to world+dog.

Sponner advises that, as a precaution, people should downgrade their libpcap to a trusted
version and be cautious of statically compiled pcap based programs. These programmes should be run in a sandbox to make sure they are not trying to connect to the mars.raketti.net server.

Posting version of popular applications contaminated with trojan code has become a popular tactic among denizens in the digital underground.

In October a trojanised version of Sendmail was found circulating the Internet. Experts later noted the marked similarities between this trojan to a backdoor planted in OpenSSH in late July. ®

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