Highly destructive Linux worm mutating

And we owe the FBI an apology

The recently discovered Lion worm, which attacks Linux BIND (DNS) servers, is turning out to be one nasty little package which leaves infected victims with no choice but to re-format their entire systems and rebuild from scratch.

We recently received a copy of a version which was released late last week, thanks to a Register reader who prefers to remain anonymous. On examining the package, we were immediately struck by how sophisticated and functional it is, and yet how kiddie-friendly it is as well. It obviously took considerable ingenuity and forethought to create, yet requires almost none to deploy (a bit like SubSeven in that regard).

It's also exceptionally destructive, as we confirmed from examining the logs of one victim who ran the Lionfind detection utility on his infected system after having cleaned up manually as well as he could. The number of files and directories Lion infects is nothing short of staggering.

And it's mutating, so to speak. We had a word with Matt Fearnow at the SANS Institute, who broke the news about Lion in an advisory posted late last week. On Tuesday of this week, an upgraded version was released, Fearnow told The Register.

This one includes a feature similar to one in the Ramen worm, which altered the Web pages of hacked HTTP servers with the message "Hackers looooooooooooove noodles," signed by the "RameN Crew."

The new Lion worm sets up an HTTP server on port 27374 and erects a page bearing greetz from the Lion crew, Fearnow told us.

All versions (there are three now) are virtually idiot proof, fire-and-forget tools. Each package contains a scanner which generates random class B addresses searching for an opening on port 53. It then queries the version, and if it finds it's vulnerable, runs a well-known BIND 8 transaction signature (TSIG) handling code exploit, and installs the t0rn rootkit.

It records all successful installations in an IP log file, which it sends to the attacker via e-mail once every twelve hours.

At present the Lionfind utility, by William Stearns, will detect, but not clean, the Lion worm. Stearns is working on a cleaner as well, but considering the large amount of destruction Lion causes we're not holding our breath. SANS's Fearnow says he hopes victims have a good backup. "My best advice right now is just to re-format and re-install," he confirmed.

Shoutz to the NIPC

We were hasty this week in our initial coverage, where we took a swipe at the FBI's National Infrastructure Protection Center (NIPC) over a Lion advisory bulletin of theirs which we deemed alarmist.

"The NIPC has received reports of an Internet worm named 'Lion' that is infecting computers and installing distributed denial of service (DDoS) tools on various computer systems," the bulletin warns.

That sounded like bollocks to us because the SANS advisory made no mention of it, and because we could find no evidence of a DDoS tool in the version of Lion which we evaluated; but actually, they're half right.

According to SANS, the first version of Lion did come bundled with a DDoS tool called Tribal Flood Network (tfn2k); though it does not, as the NIPC strongly implies, install it automatically.

So the NIPC bulletin is a bit gaseous, but not as grossly flatulent as we'd thought.

Chalk it up to experience. We lost respect for the NIPC when last December they ran an alarmist bulletin with shades of terrorist designs on US power utilities, but which actually involved nothing more than a bunch of kids making use of an open FTP server to play an interactive game, as we reported here.

We were ready to imagine them crying wolf again when in reality they were only whispering wolf this time.

Sorry guys, our mistake. ®

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