Distributed firewall that learns from traffic patterns to prevent attacks

In an embodiment, a distributed firewall that learns from traffic patterns to prevent attacks is configured to receive traffic comprising one or more uniform resource identifiers (URIs), where a URI of the one or more URIs includes one or more parameters and one or more corresponding values. The firewall is configured to classify the corresponding value(s) using a pre-configured classifier and obtain a statistical rule that specifies an allowable type and an allowable length for traffic containing the one or more parameters, where the statistical rule is generated based on the classification. The firewall is configured to apply the statistical rule to incoming traffic to allow or drop requests comprising the parameter(s).