alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE APT33/CharmingKitten JS/HTA Stage 1 CnC Checkin"; flow:established,to_server; http.method; content:"GET"; http.uri; content:".php?anti="; content:"&cliname="; distance:0; fast_pattern; http.accept; content:"*/*"; endswith; http.accept_enc; content:"gzip, deflate"; endswith; http.header_names; content:"User-Agent"; content:!"Cache"; content:!"Referer"; reference:md5,e15b3d2c39888fe459dc2d9c8dec331d; classtype:targeted-activity; sid:2026575; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2018_11_05, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag APT33, tag CharmingKitten, updated_at 2020_09_16;)