alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE EvilNum CnC Checkin Response"; flow:established,to_client; http.response_body; content:"youwillnotfindthisanywhare"; bsize:<50; fast_pattern; reference:md5,0823457bcb82afff15c900f949e325f4; reference:url,www.welivesecurity.com/2020/07/09/more-evil-deep-look-evilnum-toolset/; classtype:command-and-control; sid:2030527; rev:1; metadata:attack_target Client_Endpoint, created_at 2020_07_15, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_07_15;)