Vulnerability Scanning

Overview

Vulnerability scanning serves two purposes:

• Evaluating assets for their security hardiness.

• Identifying all endpoints connected to the network.

Step one: Network scan

Performing a network scan first is standard procedure for vulnerability scanning. This is useful for asset identification, including finding items that aren’t documented or are unknown. These could be either:

• Rogue endpoints.

• Devices that have been installed for legitimate purposes but without consent from the security team.

Assets discovered and determined to be legitimate should be documented in a repository like a configuration management database (see CMDB in chapter one). Rogue devices should be found and removed from the production network as soon as possible.

Step two: Asset scan

The next step is to iterate the list of discovered assets and perform a more detailed scan of each. This is known as an asset scan, which can be very useful for finding patching opportunities. Caution should be used, however, as a scan could cause the target to fail due to excessive network activity. Some assets may need to be exempt from scanning to avoid them from crashing, though it can be said that a scan that crashes a system indicates a system that’s prone to denial of service attacks.

Types of asset scans

There are two types of asset scans:

• Authenticated

• Unauthenticated

Authenticated scans

Authenticated scans require the scanner to log onto the device, which provides much more access for the scanner and, therefore, more scan coverage. An account that follows the principle of least privilege should be created specifically for the scanner.

Unauthenticated scans

Unauthenticated scans may be safer because the scanner doesn’t log onto the asset, but the scan coverage can be less comprehensive.