Introduction to Censys for OSINT

Censys is a powerful search engine that provides visibility into devices and networks connected to the internet. For OSINT researchers, it offers valuable insights into an organization's digital footprint, infrastructure, and potential security vulnerabilities.

Getting Started with Censys

To begin using Censys, you'll need to create an account at censys.io. Censys offers both free and paid tiers, with the free tier providing basic search functionality that's sufficient for many OSINT investigations.

Basic Search Techniques

Censys allows you to search for various internet-connected assets using a flexible query language. Here are some basic search techniques:

• Domain searches: Find information about specific domains using parsed.names:example.com
• IP searches: Look up specific IP addresses with ip:8.8.8.8
• Organization searches: Find assets belonging to an organization with parsed.subject.organization:"Example Inc"

Advanced OSINT Techniques

For more sophisticated OSINT investigations, Censys offers several advanced capabilities:

Certificate Transparency Analysis

Censys indexes SSL/TLS certificates, which can reveal subdomains and related domains that might not be easily discoverable otherwise. Search for parsed.names:*.example.com to find subdomains of a target domain.

Infrastructure Mapping

By searching for an organization's name in certificate data, you can map out their digital infrastructure:

parsed.subject.organization:"Target Organization" OR parsed.subject.organizational_unit:"Target Organization"

Vulnerability Discovery

Identify potentially vulnerable systems by searching for specific software versions known to have security issues:

services.software.product:nginx AND services.software.version:1.16

Ethical Considerations

When using Censys for OSINT investigations, always adhere to ethical guidelines:

• Respect privacy and legal boundaries
• Use the information for legitimate purposes only
• Consider responsible disclosure if you discover security vulnerabilities
• Document your methodology and findings carefully

Integrating with Other OSINT Tools

Censys works best when used alongside other OSINT tools like Shodan, Google dorking, and DNS enumeration tools. Cross-referencing findings across multiple platforms can provide a more complete picture of your target's digital footprint.

Conclusion

Censys is an invaluable tool for OSINT researchers looking to understand internet-connected assets and infrastructure. By mastering its search capabilities and combining it with other OSINT techniques, you can gather comprehensive intelligence about organizations, domains, and networks.