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How a Router's Missed Range Check Nearly Crashed the Internet
Barlaam writes "A bug by router vendor A (omitting a range check from a critical field in the configuration interface) tickled a bug from router vendor B (dropping BGP sessions when processing some ASPATH attributes with length very close to 256), causing a ripple effect that caused widespread global routing instability last week. The flaw lay dormant until one of vendor A's systems was deployed in an autonomous system whose ASN, modulo 256, was greater than 250. At that point, the Internet was one typo away from disaster. Other router vendors, who were not affected by the bug, happily propagated the trigger message to every vulnerable system on the planet in about 30 seconds. Few people appreciate how fragile and unsecured the Internet's trust-based critical infrastructure really is — this is just the latest example." Vendor A, in this case, is a Latvian router vendor called MikroTik.
Reminds me of a story that Keith Marzullo told our class in a graduate level reliability class. This was back in the days of using UUCP to send email, and the vendor that he worked for had just released a "failsafe" product they were very proud of -- essentially, it was a mail router that could detect if a path went down, and would try an alternate router instead. The company touted it as a bulletproof solution.
So they go to a conference, and set up some routers, unplug some of them, etc., and everything is going fine until they ask an audience member for his UUCP address. UUCP addresses are in the form of host1!host2!host3!username, with the routing for the username explicitly specified... the addresses could thus get quite long. In this case, the guy's email address was over the buffer limit the company's routers used.
Guess what happened?
The mail server tried sending an email to the next router in the chain. The router buffer overflowed and crashed. The reliable server than tried another router... and crashed it. It then went through the entire network, and crashed every single one of the nodes, turning a bug that would have been a single point of failure into a total network collapse.
=)
Yeah, one of my favorite stories from UCSD.
Untrue. Cisco TAC wil give you the latest firmware for free, provided you tell then n\you need it due to security flaws discovered in your current version. Yoy may need to point to their blletin about the bug, but that should be trivial (http://www.cisco.com/en/US/products/products_security_advisories_listing.html)
Since Cisco almost exclusivly patches current versions due to security bugs, all their IOS are belong to us for free.