alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Job314 EK Payload Checkin"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/knock"; startswith; fast_pattern; http.user_agent; content:"Mozilla|2f|5|2e|0|20 28|X11|3b 20|Ubuntu|3b 20|Linux|20|x86|5f|64|3b 20|rv|3a|15|2e|0|29 20|Gecko|2f|20100101|20|Firefox|2f|15|2e|0|2e|1|22|"; http.header_names; content:!"|0d 0a|Referer|0d 0a|"; classtype:command-and-control; sid:2019286; rev:5; metadata:created_at 2014_09_27, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_02_23;)