alert tcp $EXTERNAL_NET any -> $HOME_NET any (msg:"ET INFO HTTP CONNECT Tunnel Attempt Inbound"; flow:established,to_server; content:"CONNECT "; nocase; content:"|0d 0a|"; within:1024; distance:0; content:"HTTP/1."; nocase; within:8; distance:-10; content:!"|3a|80"; within:4; distance:-11; content:"CONNECT "; nocase; content:"|0d 0a|"; within:1024; distance:0; content:"HTTP/1."; nocase; within:8; distance:-10; content:!"|3a|443"; within:5; distance:-12; classtype:misc-activity; sid:2000560; rev:11; metadata:created_at 2010_07_30, confidence High, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_03_07;)