Versions (5)
Version DetailsCurrent
Rev: 4 • Apr 18, 2019, 12:00 PMET MALWARE Observed Malicious SSL Cert (Unattributed CnC)
alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE Observed Malicious SSL Cert (Unattributed CnC)"; flow:from_server,established; tls.cert_subject; content:"CN=microsoftonline-secure-login.com"; nocase; endswith; tls.cert_issuer; content:"C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3"; reference:url,krebsonsecurity.com/wp-content/uploads/2019/04/wiproiocs.txt; classtype:domain-c2; sid:2027221; rev:4; metadata:attack_target Client_and_Server, created_at 2019_04_18, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_09_17, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)
Apr 18, 2019, 12:00 PM
Sep 17, 2020, 12:00 PM
Sep 21, 2024, 3:00 AM
Sep 24, 2025, 8:37 PM
rules/emerging-malware.rules