alert http $HOME_NET any -> $EXTERNAL_NET any (
msg:"ET MALWARE Operation Silk Lure Payload Request";
flow:established,to_server;
urilen:46;
http.method;
content:"GET";
http.uri;
content:"/down.php/"; startswith;
pcre:"/^(?:[a-z0-9]{32})\x2e\w{3}$/R";
http.user_agent;
content:"WindowsPowerShell"; fast_pattern;
reference:md5,f5b9ad341ccfe06352b8818b90b2413e;
reference:url,seqrite.com/blog/operation-silk-lure-scheduled-tasks-weaponized-for-dll-side-loading-drops-valleyrat;
classtype:trojan-activity;
sid:2065257; rev:1;
metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, tls_state TLSDecrypt, created_at 2025_10_20, deployment Perimeter, deployment SSLDecrypt, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_10_20, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1105, mitre_technique_name Ingress_Tool_Transfer;
target:src_ip;
)