alert tcp $EXTERNAL_NET $HTTP_PORTS -> $HOME_NET any (msg:"ET DELETED CAN-2005-0399 Gif Vuln via http"; flow:from_server,established; content:"GIF89a"; content:"|21 ff 0b|NETSCAPE2.0"; byte_test:1,!=,3,0,relative; reference:cve,2005-0399; classtype:attempted-admin; sid:2001807; rev:8; metadata:created_at 2010_07_30, signature_severity Unknown, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)