A commonly used method to secure network resources is a Virtual Private Network (VPN). They allow remote network devices to securely communicate with local resources as if they were physically plugged into the same network segment. You may even use one when working remotely to help keep your network traffic secure. While they can easily provide a lot of protection from various network attacks there are many pitfalls to avoid in order to keep the network resources secure.
One common mistake when setting up a VPN is not properly securing the devices that the VPN provides access to. Because the servers or devices will not have direct inbound internet access many times a relaxed security policy is taken. This is because it is assumed that in order to access them an attacker would first have to either be on the network directly or be connected tuourhrough the VPN. Another common mistake is not regularly updating the VPN software. There are many reasons this can occur, including avoiding downtime or not wanting to break something that appears to be working fine as is.
This week the National Security Agency (NSA) issued an advisory stating that APT groups have been actively using flaws in some popular VPN software to attack networks. They say the groups have weaponized three vulnerabilities against two pieces of VPN software, Pulse Secure VPN and Fortinet VPN. Two of the vulnerabilities, CVE-2019-11539 and CVE-201911510 specifically target Pulse Secure VPN servers. They allow remote unauthenticated command injection and arbitrary file reads on the VPN server device. The remaining vulnerability, CVE-201813379, targets Fortinet VPN servers and allows for remote unauthenticated arbitrary file reads from the server device. The National Cyber Security Center in the UK posted a separate advisory which added CVE-2018-13383 and CVE-2018-13383 to the list of vulnerabilities being used against Fortinet devices. Palo Alto Networks VPN software was also added to the vulnerable devices list with attackers utilizing CVE-2019-1579 for remote code execution on the affected VPN servers.
In total the two agencies reported six vulnerabilities against three separate VPN software vendors. For each of the affected VPN products the vulnerabilities being used could allow an attacker access to the network resources as if the attacker were physically on the network. All of the affected products have updates available to fix these flaws so it is important that they are updated immediately if an affected version is still in use. The NSA also recommends rotating any existing VPN keys or tokens just in case they were stolen before the patches were able to be applied.