alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Joanap CnC Checkin"; flow:established,to_server; http.uri; content:".ico"; http.user_agent; content:"Mozillar"; startswith; fast_pattern; http.header_names; to_lowercase; content:!"|0d 0a|referer|0d 0a|"; reference:url,securelist.com/blog/incidents/73914/operation-blockbuster-revealed/; reference:url,operationblockbuster.com/resources/index.html; classtype:command-and-control; sid:2021730; rev:7; metadata:created_at 2015_08_31, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_05_02;)