Verisign, Inc.

Sivasankar Subramanian

Suresh Bhogavilli

Yujie Zhao

Anupam Kulkarni

Steven Bowers

A method for mitigating a denial of service attack includes determining, for a client, a number of requests being transmitted to a server and determining, for the client, that the number of requests for a time period is greater than a top talker threshold. The method includes classifying the client as a top talker based on the number of requests being greater than the top talker threshold and identifying, for the client, additional requests being transmitted to the server. The method also includes determining whether a number of the additional requests matches one or more attack patterns and preventing one or more of the additional requests from being transmitted to the server if the number of additional requests that matches one or more attack patterns is greater than a first threshold.

Techniques for automatically mitigating denial of service attacks via attack pattern matching

In one embodiment, a rule optimization application optimizes a rule set that a firewall applies to protect web applications from on-line attacks. The rule optimization application identifies a completed filtering operation that is associated with applying a rule to a request to access a web application received from a client. The rule optimization application then estimates a quality score for the rule based on the completed filtering operation and a reputation value for the client that indicates a likelihood that the client is legitimate. Subsequently, the rule optimization application determines that the quality score does not satisfy a predetermined quality criterion and disables the rule in the rule set to generate a updated, optimized rule set for the web application. Advantageously, the quality criterion may configure the rule optimization application to automatically update the rule set to reduce the number of legitimate requests that are blocked by the rule set.

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Herndon, VA, United States of America

Sivasankar Subramanian