CVE-2024-40766: Critical Improper Access Control Vulnerability Affecting SonicWall Devices

Last updated at Fri, 04 Oct 2024 19:50:45 GMT

On August 22, 2024, security firm SonicWall published an advisory on CVE-2024-40766, a critical improper access control vulnerability affecting SonicOS, the operating system that runs on the company’s physical and virtual firewalls. While CVE-2024-40766 was not known to be exploited in the wild at the time it was initially disclosed, the SonicWall advisory was later updated to note that “this vulnerability is potentially being exploited in the wild.”

As of September 9, 2024, Rapid7 is aware of several recent incidents (both external and Rapid7-observed) in which SonicWall SSLVPN accounts were targeted or compromised, including by ransomware groups; evidence linking CVE-2024-40766 to these incidents is still circumstantial, but given adversary interest in the software in general, Rapid7 strongly recommends remediating on an emergency basis. Vulnerabilities like CVE-2024-40766 are frequently used for initial access to victim environments.

SonicWall’s advisory indicates CVE-2024-40766 is an improper access control vulnerability “in the SonicWall SonicOS management access and SSLVPN, potentially leading to unauthorized resource access and in specific conditions, causing the firewall to crash.” The vulnerability was added to the U.S. Cybersecurity and Infrastructure Security Agency’s (CISA) list of known exploited vulnerabilities (KEV) on September 9, 2024.

Mitigation guidance

Per the vendor advisory, CVE-2024-40766 affects SonicWall Gen 5 and Gen 6 devices, as well as Gen 7 devices running SonicOS 7.0.1-5035 and older versions.

Affected versions and platforms include:

• SOHO (Gen 5): 5.9.2.14-12o and older versions affected
• Gen6 Firewalls: 6.5.4.14-109n and older versions affected (see the advisory for a full list of affected devices)
• Gen7 Firewalls: SonicOS build version 7.0.1-5035 and older versions affected, but SonicWall recommends installing the latest firmware (see the advisory for a full list of affected devices)

SonicWall recommends restricting firewall management access to trusted sources and/or ensuring firewall WAN management is not accessible from the public internet. They similarly recommend that SSLVPN access is limited to trusted sources, and/or disabling SSLVPN access from the internet.

Rapid7 customers

InsightVM and Nexpose customers will be able to assess their exposure to CVE-2024-40766 with a vulnerability check expected to be available in today's (Tuesday, September 10) content release.