Rule History

SID: 2025190 • Source: et/open

Versions (4)

Version DetailsCurrent

Rev: 3 • Jan 9, 2018, 12:00 PM

Message:

ET HUNTING Observed Let's Encrypt Certificate for Suspicious TLD (.gdn)

Rule:

alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET HUNTING Observed Let's Encrypt Certificate for Suspicious TLD (.gdn)"; flow:established,to_client; tls.cert_subject; content:".gdn"; endswith; tls.cert_issuer; content:"Let's Encrypt"; classtype:bad-unknown; sid:2025190; rev:3; metadata:attack_target Client_Endpoint, created_at 2018_01_09, deployment Perimeter, confidence Medium, signature_severity Minor, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_09_16;)

Created:

Jan 9, 2018, 12:00 PM

Updated:

Sep 16, 2020, 12:00 PM

DB Created:

Sep 21, 2024, 3:00 AM

DB Updated:

Sep 29, 2025, 9:34 PM

Filename:

rules/emerging-hunting.rules