Rule: -- Sid: 119-5 -- Summary: This event is generated when the pre-processor http_inspect detects network traffic that may constitute an attack. -- Impact: Unknown. This may be an attempt to obfuscate an attack an evade an IDS. -- Detailed Information: This event is generated when the pre-processor http_inspect detects base36 encoded characters in a web request. This may be used in an attempt to obfuscate an attack against a webserver or to evade an IDS. -- Affected Systems: Microsoft IIS web servers (Asian) -- Attack Scenarios: An attacker need only encode a web request using base 36 encoding. -- Ease of Attack: Simple. Exploits exist -- False Positives: None Known. -- False Negatives: None Known. -- Corrective Action: Check the target host for signs of compromise. Apply any appropriate vendor supplied patches. -- Contributors: Daniel Roelker <droelker@sourcefire.com> Sourcefire Vulnerability Research Team Nigel Houghton <nigel.houghton@sourcefire.com> -- Additional References: HTTP IDS Evasions Revisited - Daniel Roelker http://docs.idsresearch.org/http_ids_evasions.pdf --
