Versions (4)
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Rev: 1 • Jun 2, 2023, 12:00 PMET WEB_SERVER LEMURLOOT WebShell Interaction Header - X-siLock-Step1 -2 Health Check User Delete Request - Observed in MOVEit File Transfer - INBOUND
alert http $EXTERNAL_NET any -> [$HOME_NET,$HTTP_SERVERS] any (msg:"ET WEB_SERVER LEMURLOOT WebShell Interaction Header - X-siLock-Step1 -2 Health Check User Delete 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-Step1|0d 0a|"; fast_pattern; nocase; http.header; content:"X-siLock-Step1|3a 20|-2"; nocase; 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:2046051; rev:1; metadata:attack_target Web_Server, created_at 2023_06_02, deployment Perimeter, deployment SSLDecrypt, malware_family LEMURLOOT, performance_impact Low, confidence Medium, signature_severity Major, tag WebShell, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_06_02; target:dest_ip;)
Jun 2, 2023, 12:00 PM
Jun 2, 2023, 12:00 PM
Sep 21, 2024, 3:00 AM
Aug 22, 2025, 9:34 PM
rules/emerging-web_server.rules