alert tcp $EXTERNAL_NET any -> $HOME_NET 23 (msg:"ET DOS Catalyst memory leak attack"; flow:to_server,established; content:"|41 41 41 0a|"; depth:20; reference:url,www.cisco.com/en/US/products/products_security_advisory09186a00800b138e.shtml; classtype:attempted-dos; sid:2000011; rev:8; metadata:created_at 2010_07_30, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)