alert http $HOME_NET any -> $EXTERNAL_NET any (
msg:"ET MALWARE CastleLoader Task Complete in URI (GET)";
flow:established,to_server;
urilen:28;
http.method;
content:"GET";
http.uri;
content:"/service/tasks/complete/id/"; fast_pattern;
http.header;
content:"cache|2d|control|3a 20|no|2d|cache"; nocase;
content:"pragma|3a 20|no|2d|cache"; nocase;
http.header_names;
content:!"|0d 0a|referer|0d 0a|"; nocase;
reference:md5,835ab1cf597812b0e6464c2e8f100678;
classtype:trojan-activity;
sid:2064007; rev:1;
metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, tls_state plaintext, created_at 2025_08_13, deployment Perimeter, malware_family CastleLoader, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_08_13;
target:src_ip;
)