Saturday, October 29, 2011

You're Doing It Wrong, Returning Scoundrels

The numbers are in. The slow dunces still don't get it.

After five days of activity and no wins on my machines, the Hail Mary Cloud moved on. That means we have yet another complete set of data to summarize and analyze. The numbers are:

A total of 4773 attempts, none of them successful, involving 338 distinctive source addresses, the most active host (, according to whois located somewhere in the Netherlands, made 109, while at the other end of the scale 30 hosts made only a single attempt). The wannabe attackers attempted to access 944 different user names, the most frequently attempted user name by far was root, with several blocks of root-only accesses even during the otherwise purely alphabetical stage.

The current sample is too small to support any far reaching conclusions, but it is tempting to speculate that with only 338 hosts participating we are seeing an indication that their success rate is sinking (previous attempts counted a cople of thousand hosts), even though they may be at least partially succeeding in their secondary goal: avoiding detection. That success is partial at best, this blog post and the earlier ones pluss varied commentary at Slashdot are indications that at least some of us are paying attention to our logs.

Another few observations worth making: 1) I have still not seen any of these sequences aimed at my Internet-facing OpenBSD systems, only Linux and FreeBSD ones. 2) It's likely that the miscreants are directing their attempts at several targets at the same time, so this sample is only a tiny fraction of the whole.

Reports of similar activity are surfacing from elsewhere, but very few people appear to be willing to share their data. It is of course even possible that the earlier episodes generated enough noise that better password policies (or preferably key logins only policies) are now in place, frustrating the random password guessers' attempts.

Whether or not you have been seeing these sequences in you authentication logs, please do yourself a favor and study your logs every now and then. It might even be worth the trouble to set up some kind of log collection and analysis infrastructure. Europeans may have to consider the legal implications of storing logs in light of the Data Retention Directive, denizens of the great elsewhere would do well to check if any similar legislation applies.

Good night and good luck.

Broken link fixed, sorry. Also, of course this has been discussed earlier, most recently in this post, also in this one as well as A low intensity, distributed bruteforce attempt (December 2, 2008), A Small Update About The Slow Brutes (December 6, 2008), Into a new year, slowly pounding the gates (December 21, 2008), The slow brutes, a final roundup (January 22, 2009) and The slow brute zombies are back (April 12, 2009). Read those for further info.

Update 2011-11-06: Another round of attempts has started, see the data aggregation page for the November 2011 entries. Of particular interest, perhaps is the List of participating hosts, sorted by number of attempts.

Update 2011-11-06 part 2: A note over at the ISC, "New, odd SSH brute force behavior" linked here, generating some additional traffic. Commenting over there requires a login and the confirmation email appears to be delayed by greylisting, so I'll comment here instead: I would not call this a particularly new approach. We've been seeing these attempts on and off since we started noticing them sometime in 2008, and it's entirely possible that there have been earlier attempts that did slip in under our radars. Analyses based on data from other sites beside mine would be very welcome indeed.

Update 2011-11-20: They keep coming back, now again after taking a 9 day breather (or possibly poking elsewhere in the meantime). Data accumulating again at the Hail Mary Cloud Data Page, with notes on the most recent activity at the very end. Please do play with the data, there's hope yet that some useful insights are to be found.

Note: A Better Data Source Is Available
Update 2013-06-09: For a faster and more convenient way to download the data referenced here, please see my BSDCan 2013 presentation The Hail Mary Cloud And The Lessons Learned which summarizes this series of articles and provides links to all the data. The links in the presentation point to a copy stored at NUUG's server, which connects to the world through a significantly fatter pipe than has.


  1. Oh, well. After the pounding on port 22, they started on 110. This time, they beat e few times on every username and triggers the alarm. Too bad for them, 6 tries and they're out for a week. Got anything like that in your logs?

  2. Inspired by this, I have to do some statistics of my own. I've kept an eye on traffic for years, as for some reason I've always been a very busy target.

    At one point I had a week or two of childlike excitement, when I discovered I could pour the IPs (of hosts trying too many ssh-connections too often) automatically into a blacklist and have PF completely ignore everything from those IPs.

    After this I kinda lost interest in the whole thing, had two more children and have been busy!


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