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The route back from a DoS attack can be long and hard

Did you ever have one of those days? Network administrators have been suffering from a succession of them recently.

Did you ever have one of those days? Network administrators have been suffering from a succession of them recently.

Having suffered batterings from Blaster and Sobig, news last week of a further three critical vulnerabilities in Windows and Internet Explorer went down like a lead balloon.

The flaws could allow infections intended to secure vehicles for use in further denial of service attacks (known as "DoS" attacks). A commonly used malicious tool, DoS attacks arrange for a large number of infected web-connected machines to send simultaneously repeated requests to a particular server. The target is overwhelmed and crashes, frequently bringing websites down, and sometimes stalling whole networks.

So in days like these, what an IT manager really doesn't need is to face a DoS attack from an otherwise respectable hardware manufacturer. But that was what happened to the University of Wisconsin earlier this summer.

Residential network specialist Netgear sells thousands of low cost routers a year. If a network was a house, a router would be the entrance hall, linking various parts of the network with the outside world. Routers often have to carry out tasks at particular times, and so synchronise themselves with special computers on the internet that pass on the correct date and time. If a `time server' fails to respond, the router repeats the request until the information is provided.

Netgear produced over 700,000 routers that aimed this information at one single server belonging to the University of Wisconsin, and were programmed to repeat the request every second. By the end of June, over 500,000 routers were bombarding the university's server with over 250,000 requests a second.

Netgear has produced a corrective patch, but since these machines are used predominantly in the home, many will never be fixed. The university reported that the "unexpected behaviour of these products presents a significant operational problem for years to come". Unsurprisingly Netgear is stumping up funds to help the university deal with the issue.

* Matthew Rippon is senior solicitor specialising in intellectual property and information technology at Watson Burton in Newcastle

 

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