Another source distribution trojan [LWN.net]

Here we go again... the source distribution of a popular application has been compromised by a trojan horse. This time around, the affected application is tcpdump, which was compromised on November 11 and remained available for download for two days. As with other trojans, this one opens up a connection to a remote host, which can then execute shell commands. The fact that tcpdump was compromised allowed an additional twist, however: tcpdump will not show traffic to and from the hostile remote system.

For more information, see this CERT advisory.