alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE APT33/CharmingKitten Retrieving New Payload (flowbit set)"; flow:established,to_server; flowbits:set,ET.APT33CharmingKitten.1; http.method; content:"GET"; http.uri; content:"/images/static/content/"; depth:23; fast_pattern; endswith; http.header_names; content:!"Cache"; content:!"Accept"; content:!"Referer"; reference:md5,9881bccf12fd8ae71a03247d2ad61a06; classtype:targeted-activity; sid:2026577; 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;)