A hypertext transport protocol (HTTP) inspection engine for an intrusion detection system (IDS) includes an HTTP policy selection component, a request universal resource identifier (URI) discovery component, and a URI normalization module. The HTTP policy selection component identifies an HTTP intrusion detection policy using a packet. The request URI discovery component locates a URI within the packet. The URI normalization module decodes an obfuscation within the URI. In another embodiment, a packet transmitted on the network is intercepted. The packet is parsed. An Internet protocol (IP) address of the packet is identified. An HTTP intrusion detection policy for a network device is determined. A URI is located in the packet. A pattern from an intrusion detection system rule is compared to the located URI. In another embodiment, an IDS includes a packet acquisition system, network and transport reassembly modules, an HTTP inspection engine, a detection engine, and a logging system.