Verisign, Inc.

Yujie Zhao

Suresh Bhogavilli

Roberto Guimaraes

Sivasankar Subramanian

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.

Automatically optimizing web application firewall rule sets

Methods and systems for mitigating denial-of-service attacks include a proxy server that monitors a set of application servers configured to receive and service requests from clients. The proxy server intercepts the requests, and in response, provides the clients with customized client-side scripts embedded in markup language. The client-side scripts may include random strings to generate follow-through random uniform resource identifier redirection requests expected by the proxy server. The client-side scripts, upon execution, may challenge the clients by demanding user interaction within a specified period of time, requesting a delay before responding, and/or attempting to set a challenge cookie multiple times. If a client provides the demanded user interaction within the specified time, honors the delay, and/or sets the challenge cookie with the correct value, then the client-side scripts may generate a redirection request expected by the proxy server for that client and the proxy servers may whitelist that client for a configurable duration and forward that client's subsequent requests to the application servers without challenge.

Client-side active validation for mitigating DDOS attacks

Embodiments relate to systems, devices, and computer-implemented methods for mitigating Distributed Denial of Service ('DDoS') attacks. The method can include receiving, by a server, a response message from an application server. The method can further include determining a source internet protocol (IP) address associated with the source client based on a request message received from a source client. The request message received from the source client corresponds to the response message received from the application server. In addition, the method can include identifying, by the server, a plurality of counters associated with the source IP address, and identifying, by the server, a response type of the response message. Further, the method can include causing a value of at least one of the plurality of counters to change based on the response message and the response type.

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Reston, VA, United States of America

Yujie Zhao