alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Arkei/Vidar/Mars Stealer Variant CnC checkin commands"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/windbg"; fast_pattern; bsize:7; http.content_len; byte_test:0,<,84,0,string,dec; http.header_names; content:!"Referer"; http.request_body; content:"Content-Disposition|3a 20|form-data|3b 20|name|3d 22|type|22 0d 0a 0d 0a|"; pcre:"/^(?:ct_start|chr_start|moz_start|grb_start|upl_start)/R"; reference:md5,844ab1b8a2db0242a20a6f3bbceedf6b; classtype:trojan-activity; sid:2038523; rev:1; metadata:attack_target Client_Endpoint, created_at 2022_08_15, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_08_15, reviewed_at 2025_07_14;)