A worm called x.c, which takes advantage of a buffer overflow vulnerability in the telnet daemon program commonly used on Unix boxes, has being discovered, and security experts fear it is a harbinger of worse to come.
Many of these organisations, such as the FBI's National Infrastructure Protection Centre, overplayed the destructive nature of the Code Red worm but that's not to say there isn't a problem here. The security loophole might allow an attacker to take control of a victim's system, and it is suspected as the root cause behind a number of recent hacks, so it's well worth reviewing the vulnerability.
The flaw, which was first reported last month, primarily affects BSD-derived Telnet daemons, which are used on Solaris, AIX, HP-UX and several versions of Linux-based servers, for example. More information on affected systems, possible workarounds and how to obtain fixes has been published by CERT and is available here. ®
In our original story we had a headline that warned that the telnetd bug. This is an oversimplification that we've now deleted.