The U.S. National Security Agency and Cybersecurity and Infrastructure Security Agency have jointly released a new guidance resource on selecting and hardening virtual private network (VPN) solutions to help organizations address security risks associated with the popular tools.
Especially in this new age of remote/hybrid work, VPNs have become a popular resource for organizations with a dispersed workforce as they are designed to keep information sent over the internet private and secure, but they can be vulnerable to exploitation by malicious actors, the agencies say.
The guidance is designed to help organizations select standards-based VPN solutions and harden those networks to prevent compromise from bad actors.
The agencies define VPNs as a tool that allow users to remotely connect to a corporate network via secure tunnel.
“Through this tunnel, users can take advantage of the internal services and protections normally offered to on-site users, such as email/collaboration tools, sensitive document repositories, and perimeter firewalls and gateways,” the agencies say. “Because remote access VPN servers are entry points into protected networks, they are targets for adversaries.”
The document provides guidance on how to select a standards-based VPN from a reputable vendor with a track record of quickly fixing vulnerabilities and other best practices, as well as hardening the VPN by configuring strong cryptography and authentication, running only strictly necessary features and protecting and monitoring access.
According to the agencies, bad actors exploit VPNs to harvest credentials, weaken encrypted traffic sessions, remotely execute code on the VPN device, intercept encrypted traffic and read sensitive data.
Those activities are largely designed to give the bad actor a stronger foothold in a victim’s environment, which could result in a much larger compromise of the organization.
The guidance calls for a comprehensive audit of any VPN provider and ensuring the products use industry standard tools and practices, as well as requesting a software bill of materials to understand exactly what is in the product.
In addition, organizations should work to harden the VPN against compromise by using cryptographic algorithms as specified by NIST and other organizations, securely configuring the VPN, using trusted sever certificates and more.
To reduce the VPN’s attack surface, organizations are urged to immediately apply patches and updates, especially for known vulnerabilities. Access to the VPN device should be restricted by port and protocol, and intrusion prevent systems, and firewalls should also be deployed. Network segmentation and logging should also be implemented, according to the document.