alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"ET CHAT Yahoo IM ping"; flow:to_server,established; content:"YMSG"; nocase; depth:4; content:"|00 12|"; offset:10; depth:2; classtype:policy-violation; sid:2001255; rev:6; metadata:created_at 2010_07_30, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)