Before diving into Nessus Scanner, it’s essential to understand Passive Information Gathering, a foundational skill in cybersecurity. This step involves collecting information about a target system or network without directly interacting with it. Passive information gathering is crucial because it helps you build an understanding of the environment without triggering any alarms or alerts.
Passive techniques allow you to identify key information about your target, such as IP ranges, domain details, DNS records, employee information, and technologies in use. These insights set the stage for effective vulnerability assessment with Nessus.
Key Components of Passive Information Gathering:
- Open-Source Intelligence (OSINT):
Use publicly available tools and resources, such as search engines, social media platforms, and WHOIS databases, to gather details about your target. This step is entirely non-intrusive, as it relies on information that is already exposed on the internet. - DNS Reconnaissance:
Analyze domain records to uncover subdomains, MX records, TXT entries, and other DNS data. Tools likedig,nslookup, or online services like DNSDumpster are invaluable for this process. - Network Mapping:
Collect IP range information and understand the target’s network layout. Resources like ARIN, RIPE, or APNIC can help identify ownership and range details. - Technology Fingerprinting:
Discover what technologies the target uses, such as web servers, programming languages, or CMS platforms. Tools like BuiltWith or Netcraft provide insights into the technology stack, which can be critical for identifying vulnerabilities later. - Social Engineering Data Collection:
Passively gather information about employees, emails, and organizational structure through social media platforms like LinkedIn, Facebook, or even company websites. This information can be useful for security assessments and testing social engineering vulnerabilities.
Tools for Passive Information Gathering:
- Shodan: A search engine for devices connected to the internet, providing insights into exposed systems, their ports, and services.
- Maltego: A powerful OSINT tool that visually maps relationships between entities like domains, people, and organizations.
- Google Dorking: Advanced search techniques that use Google to uncover sensitive data or misconfigurations.
- Recon-ng: A framework for gathering open-source intelligence in a structured way.
Why It’s Important for Nessus Users:
When conducting a Nessus scan, knowing the details of your target in advance improves scan accuracy and efficiency. It minimizes the risk of scanning unnecessary or unintended systems and ensures you configure Nessus policies and settings in alignment with the target’s environment.
In conclusion, Passive Information Gathering is the silent groundwork that ensures your vulnerability assessment is thorough and impactful. Don’t skip this step—it is the first step toward mastering Nessus and understanding your network landscape effectively.
