Rule: -- Sid: 119-9 -- 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 or an attempt to evade an IDS. -- Detailed Information: This event is generated when the pre-processor http_inspect detects a "\" character being used where a "/" is normally expected in a web request. This may be an attempt to obfuscate an attack or an attempt to evade an IDS. -- Affected Systems: Microsoft IIS web servers. -- Attack Scenarios: An attacker merely needs to use a "\" character instead of a "/"' in a web request. -- Ease of Attack: Simple. -- 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 --
