alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE DOUBLEBACK CnC Activity"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/admin"; startswith; content:"/client.php"; within:13; endswith; fast_pattern; pcre:"/^\/admin(?:[0-9]{1,2})?\/client\.php$/"; http.header_names; content:!"|0d 0a|Referer|0d 0a|"; http.content_type; content:"multipart/form-data"; bsize:19; reference:url,twitter.com/k3dg3/status/1532454383631450115; reference:url,www.mandiant.com/resources/unc2529-triple-double-trifecta-phishing-campaign; classtype:command-and-control; sid:2036823; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2022_06_03, deployment Perimeter, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_01_20;)