Faulty Rules Foul Router Protection

摘要

THIS WEEK, my team and I discovered a vulnerability in the Cisco Systems Inc. equipment we use in our global network. There are 253 possible IP-based protocols in IP Version 4, and the majority of Cisco routers and switches have a serious problem with four of them. The flaw leaves un-patched equipment open to denial-of-service attacks. Once the Cisco device receives a certain number of IP packets of Type 53, 55, 77 or 103, it stops functioning. If a switch or router doesn't know what to do with a given packet, it just leaves it in the queue until the queue fills up and the device stops working.