Versions (3)
Version DetailsCurrent
Rev: 1 • Jun 2, 2023, 12:00 PMET WEB_SERVER LEMURLOOT WebShell Interaction Header - X-siLock-Step1 -1 Data Exfil Response - Observed in MOVEit File Transfer - OUTBOUND (Active Compromise)
alert http [$HOME_NET,$HTTP_SERVERS] any -> $EXTERNAL_NET any (msg:"ET WEB_SERVER LEMURLOOT WebShell Interaction Header - X-siLock-Step1 -1 Data Exfil Response - Observed in MOVEit File Transfer - OUTBOUND (Active Compromise)"; flow:established,to_client; http.header_names; content:"|0d 0a|X-siLock-Comment|0d 0a|"; content:"|0d 0a|AzureBlobStorageAccount|0d 0a|"; content:"|0d 0a|AzureBlobKey|0d 0a|"; content:"|0d 0a|AzureBlobContainer|0d 0a|"; fast_pattern; nocase; 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:successful-admin; sid:2046050; 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 Critical, tag WebShell, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_06_02; target:src_ip;)
Jun 2, 2023, 12:00 PM
Jun 2, 2023, 12:00 PM
Jun 3, 2023, 12:00 AM
Aug 22, 2025, 9:34 PM
rules/emerging-web_server.rules