analyzing-tls-certificate-transparency-logs

Query crt.sh CT logs to detect phishing domains and unauthorized certificates.

Updated Apr 23, 2026
One-click install
npx skills add https://github.com/YukiIto1999/ctf-sleuth --skill analyzing-tls-certificate-transparency-logs
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: analyzing-tls-certificate-transparency-logs
Source: https://github.com/YukiIto1999/ctf-sleuth/tree/main/.claude/skills/analyzing-tls-certificate-transparency-logs
Command: npx skills add https://github.com/YukiIto1999/ctf-sleuth --skill analyzing-tls-certificate-transparency-logs

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill requires requests, pycrtsh, and includes scripts (resource) and references (resource) components.

What problem does it solve?

Certificate Transparency (CT) logs are a primary source for tracking valid certificates issued for domains. This Skill queries crt.sh and the pycrtsh library to help detect phishing domains, unauthorized certificate issuance, and shadow IT across an organization's assets.

Core Features & Use Cases

  • Query CT logs to identify typosquatting and suspicious domains related to a target brand.
  • Detect certificates issued by unauthorized Certificate Authorities and wildcard certs.
  • Support incident response, threat hunting, and security monitoring across multiple domains.

Quick Start

Run the TLS CT analysis agent against your target domain to generate a findings report.

Frequently Asked Questions about analyzing-tls-certificate-transparency-logs

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I detect phishing domains using Certificate Transparency logs?

Certificate Transparency logs track valid certificates issued for domains to help detect phishing domains and unauthorized certificate issuance. By querying these logs, you can identify typosquatting and suspicious domains targeting your brand.

How to query crt.sh for unauthorized TLS certificates and wildcard certs?

Querying crt.sh with the pycrtsh library retrieves TLS certificate data to detect unauthorized certificate issuance and wildcard certs. The Skill uses Python 3.8+ to query these logs and produce structured findings for security monitoring.

Do I need Python and pycrtsh to monitor CT logs for incident response?

Yes, you need Python 3.8+ with the pycrtsh and requests libraries to monitor CT logs for incident response. These dependencies query crt.sh to produce structured findings for threat hunting and ongoing security monitoring across domains.

What is the best way to track typosquatting domains across multiple brands?

Analyzing Certificate Transparency data is an effective way to track typosquatting domains across multiple brands. The Skill queries CT logs to identify suspicious domains and supports ongoing monitoring across an organization's assets.

Can I use Certificate Transparency analysis for ongoing security monitoring?

Yes, Certificate Transparency analysis supports ongoing security monitoring across multiple domains. It queries crt.sh to detect unauthorized certificate issuance, rogue TLS certs, and shadow IT assets for continuous threat hunting.