Trojan Found in libpcap and tcpdump
Members of The Houston Linux Users Group discovered that the newest sources of libpcap and tcpdump available from tcpdump.org were contaminated with trojan code. HLUG has notified the maintainers of tcpdump.org.
The trojan contains modifications to the configure script and gencode.c (in libpcap only).
The configure script downloads http://mars.raketti.net/~mash/services which is then sourced with the shell. It contains an embedded shell script that creates a C file, and compiles it.
The program connects to 126.96.36.199 (mars.raketti.net) on port 1963 and reads one of three one byte status codes:
A - program exits
D - forks and spawns a shell and does the needed file descriptor manipulation to redirect it to the existing connection to 188.8.131.52.
M - closes connection, sleeps 3600 seconds, and then reconnects
It's important to note that it reuses the same outgoing connection for the shell. This gets around firewalls that block incoming connections.
Gencode.c is modified to force libpcap to ignore packets to/from the backdoor program, hiding the backdoor program's traffic.
This is similar to the OpenSSH trojan a few months ago.