alert http $EXTERNAL_NET any -> [$HOME_NET,$HTTP_SERVERS] any (
msg:"ET WEB_SERVER LEMURLOOT WebShell Interaction Header - X-siLock-Step2/3 File Retrieval Request- Observed in MOVEit File Transfer - INBOUND";
flow:established,to_server;
http.header_names;
content:"|0d 0a|X-siLock-Comment|0d 0a|";
content:"|0d 0a|X-siLock-Step2|0d 0a|"; fast_pattern; nocase;
content:"|0d 0a|X-siLock-Step3|0d 0a|";
threshold:type limit, count 1, seconds 300, track by_src;
reference:url,www.huntress.com/blog/moveit-transfer-critical-vulnerability-rapid-response;
reference:url,community.progress.com/s/article/MOVEit-Transfer-Critical-Vulnerability-31May2023;
reference:md5,af136505d384c9a89635b365e55b7fa3;
reference:url,www.mandiant.com/resources/blog/zero-day-moveit-data-theft;
classtype:attempted-admin;
sid:2046052; rev:1;
metadata:attack_target Web_Server, created_at 2023_06_02, deployment Perimeter, deployment SSLDecrypt, malware_family LEMURLOOT, performance_impact Low, confidence High, signature_severity Major, tag WebShell, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_06_02;
)