""ET INFO Lets Encrypt Free SSL Cert Observed with IDN/Punycode Domain - Possible Phishing""

SID: 2024227

Revision: 1

Class Type: policy-violation

Metadata: affected_product Web_Browsers, attack_target Client_Endpoint, created_at 2017_04_19, deployment Perimeter, signature_severity Critical, tag Phishing, updated_at 2017_04_19, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1566, mitre_technique_name Phishing

Reference:

Protocol: tcp

Source Network: $EXTERNAL_NET

Source Port: 443

Destination Network: $HOME_NET

Destination Port: any

Flow: established,from_server

Contents:

  • Value: "|55 04 0a|"

  • Value: "|0d|Let|27|s Encrypt"

  • Value: "|55 04 03|"

  • Value: "|78 6e 2d 2d|"

Within: 25

PCRE:

Special Options:

  • fast_pattern

  • nocase

source