CertScan

Overview

The CertScan (CertScan.py) is a Python script designed to analyze SSL/TLS certificates of a single domain or from a list of domains. It retrieves and evaluates certificate details such as expiration dates, issuer, cipher suite, and self-signed status. It supports multi-threaded scanning and exports results to an Excel file.

Files

1. CertScan.py: The main script containing the certificate scanning logic.
2. CertScan_YYYYMMDD-HHMMSS.log: Log file generated during execution.
3. CertScan_YYYYMMDD-HHMMSS.xlsx: Output report containing certificate details.

Dependencies

• Python standard libraries: argparse, socket, ssl, time, logging, concurrent.futures, warnings
• External libraries:
  • cryptography (for certificate parsing)
  • pandas (for report generation)
  • tqdm (for progress tracking)

Functions and Logic

scan_domain_certificate

• Purpose: Connects to a domain via SSL/TLS and retrieves certificate details.
• Logic:
  • Establishes an SSL connection to the given domain and port.
  • Extracts certificate information using cryptography.x509.
  • Checks if the certificate is expired, self-signed, or has a valid issuer.
  • Logs any SSL/TLS errors encountered.
  • Returns a structured report including expiry date, cipher suite, and certificate details.

main

• Purpose: Handles user input, manages parallel execution, and generates reports.
• Logic:
  • Parses command-line arguments.
  • Reads domains from user input or a file.
  • Uses ThreadPoolExecutor for concurrent domain analysis.
  • Saves the results to an Excel file using pandas.
  • Logs errors and progress updates.

Usage

Command-line Arguments

Argument	Description
-a, --address	Single domain to analyze.
-l, --list	File containing multiple domains.
-p, --port	Port to scan (default: 443).
-t, --timeout	Timeout per connection attempt (default: 5s).
-r, --retries	Number of retries per domain (default: 3).
-d, --delay	Delay between retries (default: 1s).
-w, --workers	Number of concurrent workers (default: 1).
-o, --output	Prefix for the output file name.

Running the script

Scan a single domain:

python CertScan.py -a example.com

Scan multiple domains from a file with five workers:

python CertScan.py -l domains.txt -w 5

Output

• Log File (CertScan_YYYYMMDD-HHMMSS.log): Stores detailed logs of each scan attempt.
• Excel Report (CertScan_YYYYMMDD-HHMMSS.xlsx): Contains a summary of certificate details for each domain scanned.

Example Excel Report

Domain	Port	Issuer	Subject	Expiry date	Days until expiry	Is expired	Is self-signed	SSL/TLS version	Cipher suite	Protocol version	Key exchange	Trusted CA
example.com	443	CN=DigiCert Global G3 TLS ECC SHA384 2020 CA1,O=DigiCert Inc,C=US	CN=*.example.com,O=Internet Corporation for Assigned Names and Numbers,L=Los Angeles,ST=California,C=US	2026-01-15T23:59:59+00:00	316	FALSE	FALSE	TLSv1.3	TLS_AES_256_GCM_SHA384	TLSv1.3	256	TRUE

Notes

• Self-signed certificates are marked as "Is self-signed = TRUE".
• Expired certificates are flagged as "Is expired = TRUE".
• The scan may take longer depending on the number of domains, timeouts, retries, delays and workers used.

Contributions

Contributions are welcome! Feel free to submit issues or pull requests to improve the tool or contribute implementations in additional languages.