1. Introduction
1.1 Definition
OpenVAS (Open Vulnerability Assessment System) is an open-source vulnerability scanner that helps organizations identify security weaknesses in their IT infrastructure. It forms part of the larger Greenbone Vulnerability Management (GVM) framework.
1.2 Purpose
The primary objective of OpenVAS is to provide comprehensive vulnerability scanning capabilities that allow users to assess the security of their systems and networks, thus enhancing overall security and compliance with regulatory standards.
2. Key Components
2.1 OpenVAS Scanner
The core component that conducts vulnerability scans across various systems and services. It uses a range of network protocols to detect vulnerabilities.
2.2 OpenVAS Manager
This component manages the scanning processes, schedules tasks, and stores results. It acts as the central point for controlling the scanner.
2.3 Greenbone Security Assistant (GSA)
The web-based interface for OpenVAS, allowing users to configure scans, view results, and manage vulnerabilities. It provides a user-friendly way to interact with OpenVAS features.
2.4 NVT Feed
OpenVAS uses Network Vulnerability Tests (NVTs) to perform assessments. These are regularly updated scripts that identify vulnerabilities. OpenVAS users can subscribe to a feed for the latest tests.
3. Features
3.1 Comprehensive Vulnerability Scanning
OpenVAS can scan various systems, including:
Web applications
Databases
Network devices
Operating systems
3.2 Customizable Scans
Users can create custom scan configurations to focus on specific vulnerabilities, ports, or services.
3.3 Reporting
OpenVAS generates detailed reports on vulnerabilities, categorized by severity (low, medium, high). Reports can be exported in multiple formats, including PDF, HTML, and XML.
3.4 Integration Capabilities
OpenVAS can integrate with other security tools (e.g., SIEM solutions, ticketing systems) to provide a more holistic security approach.
3.5 Scheduled Scans
Users can schedule scans to run at specific intervals, ensuring continuous monitoring and assessment of vulnerabilities.
3.6 User Management
Supports multiple users with role-based access control, allowing different levels of access and functionality based on user roles.
4. Functions
4.1 Vulnerability Detection
OpenVAS utilizes its extensive database of NVTs to detect known vulnerabilities in scanned systems.
4.2 Risk Assessment
After detecting vulnerabilities, OpenVAS assesses the risk associated with each finding, helping organizations prioritize remediation efforts.
4.3 Compliance Checks
OpenVAS can perform checks against various compliance frameworks (e.g., PCI-DSS, HIPAA) to ensure that systems adhere to necessary security standards.
4.4 Patch Management Support
Provides insights into necessary patches and updates to mitigate identified vulnerabilities.
5. Uses
5.1 Security Assessments
Organizations use OpenVAS for regular security assessments to identify and address vulnerabilities before they can be exploited.
5.2 Penetration Testing Support
Penetration testers can leverage OpenVAS to identify potential attack vectors during testing phases.
5.3 Compliance Audits
Companies seeking compliance with security standards can utilize OpenVAS to demonstrate vulnerability management processes.
5.4 Risk Management
Helps organizations develop a risk management strategy by identifying vulnerabilities and assessing their potential impact.
6. Limitations
6.1 False Positives
Like many vulnerability scanners, OpenVAS can generate false positives, which may lead to unnecessary remediation efforts.
6.2 Complexity
Setting up and configuring OpenVAS can be complex for inexperienced users. Understanding its components and functionality requires some technical knowledge.
6.3 Performance Impact
Running comprehensive scans can consume significant resources, potentially affecting the performance of scanned systems and networks.
6.4 Limited Support
While there is an active community for OpenVAS, official support options are limited compared to commercial solutions. Users may need to rely on community forums for troubleshooting.
6.5 NVT Update Frequency
The effectiveness of OpenVAS relies on the frequency of NVT updates. If not kept current, the scanner may miss recent vulnerabilities.
7. Comparison with Other Tools
7.1 vs. Nessus
Nessus: A commercial product known for its comprehensive features and user-friendly interface but comes with licensing fees. OpenVAS, being open-source, has no licensing costs but may lack some advanced features found in Nessus.
7.2 vs. Qualys
Qualys: A cloud-based solution with a strong focus on compliance and asset management. Qualys is often favored for its integrated approach but requires a subscription fee.
7.3 vs. Nikto
Nikto: A web server scanner that focuses on web vulnerabilities, while OpenVAS provides broader scanning capabilities across different systems and services.
8. Installing OpenVAS on Kali Linux
OpenVAS is available in the Kali Linux repositories, making installation relatively straightforward. Follow these steps:
Step 1: Update Your System
Before installing OpenVAS, ensure your system is up to date. Open a terminal and run:
sudo apt update && sudo apt upgrade -yStep 2: Install OpenVAS
Install OpenVAS using the package manager:
sudo apt install openvas -yStep 3: Set Up OpenVAS
Once installed, you need to set up OpenVAS. This involves initializing the database and configuring the necessary components. Run the following command:
sudo gvm-setupThis command will:
Set up the PostgreSQL database for OpenVAS.
Download and compile the latest Network Vulnerability Tests (NVTs).
Step 4: Start OpenVAS Services
After the setup process, start the OpenVAS services:
sudo gvm-startStep 5: Access the Web Interface
OpenVAS comes with a web-based interface, Greenbone Security Assistant (GSA). You can access it by opening a web browser and navigating to:
https://localhost:9392Step 6: Log In
On the login page, use the default credentials:
Username: admin
Password: The password was generated during the setup process. You can find it by running:
sudo gvm-get-default-passwordStep 7: Update NVT Feed (Optional)
After logging in, it’s a good idea to update the NVT feed to ensure you have the latest vulnerability checks. You can do this through the web interface or by running:
sudo gvm-feed-updateStep 8: Configure OpenVAS
You can now configure scan targets, create tasks, and run scans through the web interface. Familiarize yourself with the various options available in GSA to make the most of OpenVAS.
Troubleshooting
If you encounter any issues starting the services, check the logs located in /var/log/gvm/.
Ensure that your firewall settings allow traffic on port 9392.
9. Practical Guide to Using OpenVAS
1. Configure Scan Targets
After logging into the Greenbone Security Assistant (GSA):
Navigate to "Scans" > "Targets":
Click on “Add” to create a new target.
Name: Give your target a meaningful name.
Hosts: Enter the IP address or hostname of the target you want to scan. You can add multiple addresses separated by commas.
Port List: You can select the default or create a custom port list.
Save the Target:
Click on “Create” to save the target configuration.
2. Create a Scan Task
Once your target is configured, create a scan task:
Navigate to "Scans" > "Tasks":
Click on “Add” to create a new task.
Name: Provide a name for your scan task.
Select Target: Choose the target you just created.
Scan Config: Select a scan configuration (e.g., Full and Fast, Host Discovery).
Schedule the Task (Optional):
You can schedule the scan to run immediately or set a specific date and time.
Save the Task:
Click on “Create” to save your scan task.
3. Run the Scan
Start the Scan:
In the "Tasks" section, find your newly created task and click the play icon to start it.
Monitor Progress:
You can view the scan progress in real-time. It may take a while depending on the number of targets and the configuration.
4. Review Scan Results
Once the scan is complete:
Navigate to "Scans" > "Results":
You will see a list of completed scans.
Click on the scan you want to review.
Examine Findings:
The results will be categorized by severity (Critical, High, Medium, Low).
Click on individual findings for detailed information, including:
Description of the vulnerability.
Affected hosts.
Recommendations for remediation.
Export Results:
You can export the results in various formats (PDF, HTML, XML) by clicking on the export button.
5. Remediation
Based on the findings:
Prioritize vulnerabilities based on their severity and impact.
Develop a remediation plan to address the vulnerabilities, which may include:
Applying patches.
Configuring firewalls.
Changing configurations.
Practical Tips
Regular Scans: Schedule regular scans (weekly or monthly) to maintain security posture.
Custom Scan Configurations: Create custom scan configurations to focus on specific vulnerabilities or compliance requirements.
Integration: Consider integrating OpenVAS with other tools (like SIEMs) for enhanced security management.
Community Resources: Utilize community forums and documentation for troubleshooting and advanced configurations.
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