Vulnerability Identification and Validation
What to scan?
Asset criticality
How important is an asset.
Not everything is critical.
People
Tangible assets
Intangible assets
Asset and Inventory Tracking
Use a dedicated tool.
Type, model, SN, ID, location, user, value, service
Group by: usage, networks, sensitivity, outside connections, financial value, legal requirements, contractual obligations
Infrastructure Vulnerability Scanner
Not nmap
Scans hosts and network devices
Looks for vulns in:
OS version and patches
Services
Configuration
Network shares
User accounts
Weak security policies
Mapping and Enumeration
Inventory of devices, services, versions, plugins, etc
Passive Scanning
Look for public info.
Capture network traffic
Don’t get involved!
Don’t interact with the target
Zero impact on network and services
Cannot be detected (mostly)
Active Scanning
Directly interact with the target
Actively send requests and analyze answers
Visible and noisy
Can create performance issues and downtime
Easily detected
Credentialed Scan
Relies on a user account
Scanner logs into the targets
Performs checks using that account
Insider point of view
Highest level of detail provided
Non-Credentialed Scan
No user account
Outsider point of view
Best for perimeter scanning
Trial and error
Not so accurate
Higher risk of downtime
Server based scanning
Connect to the server and scan
Credentialed and non-credentialed
Agent based
Application, plugin, script installed on the server
Acts as the backdoor for the scanning software
Advantages
Credentialed by default
Efficient resource usage
Works with offline devices
Disadvantages
Need to install and manage agents
Vulnerable backdoor
Segmentation: subnets, VLANs, VPNs. Reachability? Consider using a dedicated management network.
Frequency of scanning
Keep in mind
Service degradation
Time constraints
Licensing limitations
So scan at least when
Something changes
Regulations say so
After a security breach
Choosing a scanner
Free vs paid?
General purpose or specialized?
Nessus – Paid. Free for a limited number of hosts
OpenVAS – Fork of Nesuss
Qualys – cloud based service with sensors installed on networks
Last updated