alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE W32/Echmark CnC Activity M2"; flow:established,to_server; http.method; content:"HEAD"; http.uri; content:".php?u="; fast_pattern; content:"_"; distance:0; content:"&i="; distance:0; http.user_agent; content:"Microsoft BITS/"; startswith; reference:md5,d30484a523fe3d8a883738f4ec06a952; reference:md5,f9509755c5781f87788ffdf9efad075d; reference:url,twitter.com/reddrip7/status/1366703445990723585?s=21; classtype:trojan-activity; sid:2031748; rev:1; metadata:attack_target Client_Endpoint, created_at 2021_03_02, deployment Perimeter, performance_impact Moderate, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_03_02;)