Palo Alto Networks fixes critical flaw in PAN-OS firewall software

Palo Alto Networks has fixed a new critical vulnerability affecting multiple versions of PAN-OS, the operating system affecting its next-generation firewalls.

The issue received the identification number CVE-2020-2040 and has a severity score of 9.8 out of 10 and requires no user interaction. An unauthenticated attacker can exploit it by sending a malicious request to specific interfaces.

Code execution potential

In an advisory updated today, the company disclosed that the vulnerability was discovered during an internal security review by Yamata Li, a member of its Threat Research Team.

The same researcher is credited for finding another critical-severity flaw in PAN-OS (command injection CVE-2020-2034) that allows executing arbitrary commands with root privileges and without the need to authenticate.

The latest flaw affects versions 8.1 (before 8.1.15), 9.0 (before 9.0.9), and 9.1 (before 9.1.3) where the Captive Portal or the Multi-Factor Authentication is enabled.

Environments with version 10 or higher of the operating system running on physical, virtualized, or cloud-based firewall appliances need not worry about this problem.

According to the security advisory, the vulnerability is a buffer overflow that permits an attacker to disrupt system processes. There is also the potential for executing arbitrary code with root privileges.

The company highlights that unlike the previous critical vulnerabilities in PAN-OS disclosed over the summer [1, 2], this one does not impact the GlobalProtect VPN portal or the PAN-OS management interfaces.

Updating to the current latest versions of the product addresses the vulnerability. Where Prisma Access services are used, these have already been upgraded and are no longer vulnerable.

If upgrading to the latest PAN-OS is not possible, Palo Alto Networks advises enabling signatures in content update version 8317 to block attacks against CVE-2020-2040.

Palo Alto Networks says that at this time there is no evidence to suggest that the vulnerability is actively exploited in the wild and there are no indicators of compromise or breach at this time.