The Rising Tide: DDoS by Defective Designs and Defaults

Dedicated readers will recall my article about how I tracked down the “DDoS” attack on stratum 1 time servers by various D-Link devices. I’ve now had a paper accepted at the 2nd Workshop on Steps to Reducing Unwanted Traffic on the Internet (SRUTI’06) which runs in California in early July.

The paper (PDF version available here and HTML here) gives rather more details about the problems with the D-Link firmware. More significantly, it puts this incident into context as one of a number of problems suffered by stratum 1 time servers over the past few years AND shows that these time server problems are just one example of a number of incidents involving different types of system that have been “attacked” by defective designs or poorly chosen defaults.

My paper is fairly gloomy about the prospects for improvement going forward. ISPs are unlikely to be interested in terminating customers who are running “reputable” systems which just happen to contribute to a DDoS on some remote system. There’s no evidence that system designers are learning from past mistakes — and the deskilling of program development is meaning that ever more clueless people are involved. Economic and legal approaches don’t seem especially promising — it may have cost D-Link (and Netgear before them) real dollars, but I doubt that the cost been high enough yet to scare other companies into auditing their systems before they too cause a similar problem.

As to the title… I suggest that if a classic, zombie-originated, DDoS attack is like directing a firehose onto a system; and if a “flash crowd” (or “slashdotting”) is like a flash flood; then the sort of “attack” that I describe is like a steadily rising tide, initially easy to ignore and not very significant, but it can still drown you just the same.

Hence it’s important to make sure that your security approach — be it dams and dikes, swimming costumes and life-jackets, or wetsuits and scuba gear (or of course their Internet anti-DDoS equivalents) — is suitable for dealing with all of these threats.

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