Ramblings & ephemera

An overview of Flash Worms

From Stuart Staniford, Gary Grim, & Roelof Jonkman’s “Flash Worms: Thirty Seconds to Infect the Internet” (Silicon Defense: 16 August 2001):

In a recent very ingenious analysis, Nick Weaver at UC Berkeley proposed the possibility of a Warhol Worm that could spread across the Internet and infect all vulnerable servers in less than 15 minutes (much faster than the hours or days seen in Worm infections to date, such as Code Red).

In this note, we observe that there is a variant of the Warhol strategy that could plausibly be used and that could result in all vulnerable servers on the Internet being infected in less than thirty seconds (possibly significantly less). We refer to this as a Flash Worm, or flash infection. …

For the well funded three-letter agency with an OC12 connection to the Internet, we believe a scan of the entire Internet address space can be conducted in a little less than two hours (we estimate about 750,000 syn packets per second can be fit down the 622Mbps of an OC12, allowing for ATM/AAL framing of the 40 byte TCP segments. The return traffic will be smaller in size than the outbound. Faster links could scan even faster. …

Given that an attacker has the determination and foresight to assemble a list of all or most Internet connected addresses with the relevant service open, a worm can spread most efficiently by simply attacking addresses on that list. There are about 12 million web servers on the Internet (according to Netcraft), so the size of that particular address list would be 48MB, uncompressed. …

In conclusion, we argue that a small worm that begins with a list including all likely vulnerable addresses, and that has initial knowledge of some vulnerable sites with high-bandwidth links, can infect almost all vulnerable servers on the Internet in less than thirty seconds.

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