Security in web services: an evolving threat model
Udi Manber, chief scientist at Yahoo!, apprised security researchers at the IEEE's Symposium on Security and Privacy about attacks likely to become commonplace in the emerging era of large-scale, distributed web services. "The kind of attacks that we're seeing are not a traditional security attack," he warned. The threat to web services is not about something like root access; it's more about repeated violations and exploitations of the service - small cheats and hacks that are individually insignificant, but a huge problem in the aggregate.
Spam is an example of this kind of hack. A web-based e-mail service does not suffer if one of its accounts is used for mass-mailing. When tens of thousands of accounts are abused in this way, the service can be brought to its knees. Manber calls this the "penny jar" effect, likening it to a thief who comes to a cash register and empties the penny dish every five minutes. The pennies are meant to be given away, and each instance of the loss is trivial; but if the theft continues unchecked, the service will be destroyed.
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