alert tls $EXTERNAL_NET any -> $HOME_NET any (
msg:"ET MALWARE Observed Malicious SSL Cert (Fake Gmail Self Signed - Possible Cobalt Stirke)";
flow:established,to_client;
tls.cert_subject;
content:"C=US, ST=CA, L=Mountain View, O=Google GMail, OU=Google Mail, CN=gmail.com"; bsize:74; fast_pattern;
tls.cert_issuer;
content:"C=US, ST=CA, L=Mountain View, O=Google GMail, OU=Google Mail, CN=gmail.com"; bsize:74;
reference:md5,b210c0f7687a9199de870e0cc11996c1;
classtype:domain-c2;
sid:2032952; rev:1;
metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_and_Server, created_at 2021_05_13, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_05_13, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;
)