NSA, CISA Issue Guidance on Selecting and Securing VPNs

The National Security Agency (NSA) and the Cybersecurity and Infrastructure Security Agency (CISA) this week published a new document to help government organizations select and secure virtual private network (VPN) solutions.

Meant to provide users with remote, secure access to an organization’s resources, VPNs represent entry points into protected networks that attackers often attempt to exploit in malicious attacks.

In fact, nation-state advanced persistent threat (APT) actors are known to target vulnerabilities in VPN appliances for credential harvesting, remote code execution, traffic hijacking, data leakage, or to weaken the security of encrypted traffic sessions.

“These effects usually lead to further malicious access through the VPN, resulting in large-scale compromise of the corporate network or identity infrastructure and sometimes of separate services as well,” the NSA and CISA note in the newly issued guidance.

Titled “Selecting and Hardening Remote Access VPN Solutions,” the document lists a series of recommendations to take into consideration when selecting a VPN, such as to avoid choosing a non-standard solution, to select a vendor with a proven track record, to read vendor documentation, or to ensure that the product supports strong authentication and that it has a robust code integrity check process.

After deploying a VPN solution, organizations are advised to “require only strong, approved cryptographic protocols, algorithms, and authentication credentials,” as well as to reduce the attack surface through patching in a timely manner, reviewing credentials and logs when patching vulnerabilities known to have been exploited, and restricting external access to the VPN device.

Furthermore, the agencies recommend using an intrusion prevention system and Web Application Firewalls (WAFs), implementing enhanced web application security and network segmentation, and enabling local and remote logging, to track all VPN user activity.

“Remote access VPNs are entryways into corporate networks and all the sensitive data and services they have. This direct access makes them prized targets for malicious actors. Keep malicious actors out by selecting a secure, standards-based VPN and hardening its attack surface. This is essential for ensuring a network’s cybersecurity,” the NSA and CISA conclude.

Meant to help Department of Defense, National Security Systems, and Defense Industrial Base decision makers better understand risks involved in the use of VPNs, the guidance should prove useful for private organizations as well, regardless of their size.

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