alert http $EXTERNAL_NET any -> $HOME_NET any (
msg:"ET MALWARE Possible APT Sarhurst/Husar/Hussarini/Hassar CnC Command Response";
flow:from_server,established;
http.stat_code;
content:"200";
file.data;
content:"<CHECK>"; depth:7;
content:"</CHECK><COMMAND>"; distance:0; fast_pattern;
content:"</COMMAND>"; endswith;
pcre:"/^<CHECK>(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})<\/CHECK>/";
reference:url,www.fortinet.com/blog/threat-research/hussarini---targeted-cyber-attack-in-the-philippines.html;
classtype:targeted-activity;
sid:2027708; rev:5;
metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2019_07_15, deployment Perimeter, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_03_24;
)