alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE EvilNum CnC Checkin"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/Validate/valsrv"; bsize:16; fast_pattern; http.header_names; content:"Host|0d 0a|Connection|0d 0a 0d 0a|"; content:!"User-Agent"; content:!"Referer"; content:!"Accept-"; reference:md5,0823457bcb82afff15c900f949e325f4; reference:url,www.welivesecurity.com/2020/07/09/more-evil-deep-look-evilnum-toolset/; classtype:command-and-control; sid:2030526; 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;)