On February 4th, I started seeing small numbers of the following Snort alert:
Cisco IOS HTTP configuration attempt
Here's a breakdown of the number of alerts per day for the first couple of weeks of the month:
| 2006-02-04 | 6 |
| 2006-02-05 | 4 |
| 2006-02-13 | 2 |
| 2006-02-14 | 1 |
| 2006-02-15 | 30 |
| 2006-02-16 | 26 |
There were two things that drew my attention to this activity. First, it's an old exploit (detailed in this advisory. Second, there was a sharp spike in activity starting on the 15th.
Around the same time as I noticed this, the SANS ISC Handler's Diary posted an entry about it, and they didn't know what was going on either. I contacted them about it, and have since heard nothing in reply.
I didn't think too much about this at first, but after collecting a few more days' worth of data, I noticed the following: Each source IP only attacked one destination IP, and while is usually a steady stream of 3 or 4 alerts per hour, there are some periods where I go for several hours without seeing anything. These things tend to suggest that the attacks are coordinated, probably through a single botnet.
Today, I heard from several other analysts around the planet who have seen similar traffic. I got the IPs and timestamps from a few of them and am in the process of analyzing some of the data. What I can see so far is that we've got around 280 individual attacks from ~250 unique IPs. Each of the three sites reporting has at least a few IPs in common with the others, further supporting my idea that this is all due to one big botnet.
I don't have much information yet, but big thanks to fellow #snort-gui regulars David Lowless and hewhodoesnotwishtobenamedbutknowswhoheiseventhoughIrefusetousehiscodenameJesus for providing data and sharing thoughts & ideas about this. It may all just turn out to be nothing, but the coordination and stealth involved make it interesting if nothing else.
Update 2006-02-24 15:53: I asked around on the #shadowserver channel, and have found that attacks like the ones I observed have been found in at least one active botnet (not sure if the scattered sightings are from different botnets or not).
Why they are probing for 5 year old vulnerabilities in Cisco routers is still a mystery. Maybe they just want to use them as proxies for IRC/spam/other attacks. I hope that's the extent of their ambitions.
Update 2006-03-06 11:41: Based on conversations I've had with others who are experiencing these sorts of attacks, I've concluded that the most likely scenario is that the perpetrator is hoping to gain access to Cisco devices in order to use them as IRC proxies to hide their true network address while trading credit card numbers and other illicit info. In other words, they can log on to the devices and initiate outbound network connections to IRC servers. One analyst speculated that there may be an IRC client plugin of some sort to facilitate this, and that seems like a reasonable assumption.
BTW, if this technique is used to disguise IRC, it may also be used to disguise connections to other services as well (HTTP?). This all seems like a pretty roundabout way to achieve the hypothesized goal, but certainly in keeping with technology that existed at the time the original exploit was discovered. Maybe someone is just using some old scripts they found online somewhere?
Update 2006-03-07 06:53: The Philippine Honeynet Project (which I reached via this SANS ISC diary entry) has also noticed these probes. Their analysis includes the name of the tool they believe responsible (ciscoscanner). Unaccountably, though, they're suggesting that the tool is looking for the vulnerability listed in this advisory, which doesn't seem to fit the observed data. It's good to read that some other people have finally noticed this, at least. They kind of stick out like a sore thumb if you're paying attention.