alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Suspected CloudAtlas APT Related Activity (GET)"; flow:established,to_server; http.method; content:"HEAD"; http.uri; content:"/?"; startswith; fast_pattern; content:".php?id="; distance:0; http.user_agent; content:"Microsoft Office"; startswith; http.header_names; content:!"Referer|0d 0a|"; reference:md5,a51d18cc42a9ac76d331913049cb0ffc; reference:url,twitter.com/t3ft3lb/status/1651154256294977537; classtype:trojan-activity; sid:2045304; rev:1; metadata:attack_target Client_Endpoint, created_at 2023_05_03, deployment Perimeter, deployment SSLDecrypt, performance_impact Significant, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_05_03; target:src_ip;)