New DOS Attack Is a Killer

October 3, 2008 – 1:37 PM

Things are a-brewin’ in Sweden. Sweden is not just home of the infamous bikini team, it is also the home of Outpost 24, an equally sexy software-as-a-service network scanning service, and the employer of my friend Robert E. Lee and his colleague Jack C. Louis. These guys are the inventors of UnicornScan, a user-land TCP stack turned into a port scanner. Never heard of it? Use Nmap exclusively? Well if you run Linux, I suggest checking it out, especially if missed ports in your portscan is inexcusable. But I digress.

Robert and Jack are smart dudes. I’ve known them for years, and they’ve always been one step ahead of the game. A couple of years ago, Jack found some anomalies in which machines would stop working in some very specific circumstances while being scanned. A few experiments, tons of reading through documentation, and one mysteriously named tool called “sockstress” later, and the two are now touting a nearly universal denial-of-service (DoS) attack that can be performed on almost any normal broadband Internet connection — in just a few seconds.

How bad is it? Well, in an interview — (fast-forward five minutes in to hear it in English), the two were asked if they could take out a data center. While they’ve never tried, it appears to be a totally plausible attack. Worse yet, unlike most DoS attacks, the machines often do not come back online once the attack is over. The victim system just doesn’t respond any more. Great, huh?

Robert and I talk a lot, and I asked him if he’d be willing to DoS us, and he flatly said, “Unfortunately, it may affect other devices between here and there so it’s not really a good idea.” Got an idea of what we’re talking about now? This appears not to be a single bug, but in fact at least five, and maybe as many as 30 different potential problems. They just haven’t dug far enough into it to really know how bad it can get. The results range from complete shutdown of the vulnerable machine, to dropping legitimate traffic.

The two researchers have already contacted multiple vendors since the beginning of September (I’ve had a small hand in getting them in contact with one of the vendors). Robert and Jack are waiting with no specific timeline to hear back from the affected TCP stack vendors. Think firewalls, OSes, Web-enabled devices, and so on. Yup, they’ll all need to be hardened, if the vendors can come up with a good solution to the problem. IPv6 services appear to be more affected by the fact that they require more resources and are no more secure since they still reside on top of an unhardened TCP stack.


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