SonicWall Urges Users to Patch Critical Firewall Flaw Amid Possible Exploitation

SonicWall has revealed that a recently patched critical security flaw impacting SonicOS may have come under active exploitation, making it essential that users apply the patches as soon as possible.

The vulnerability, tracked as CVE-2024-40766, carries a CVSS score of 9.3 out of a maximum of 10.

"An improper access control vulnerability has been identified in the SonicWall SonicOS management access and SSLVPN, potentially leading to unauthorized resource access and in specific conditions, causing the firewall to crash," SonicWall said in an updated advisory.

With the latest development, the company has revealed that CVE-2024-40766 also impacts the firewall's SSLVPN feature. The issue has been addressed in the below versions -

• SOHO (Gen 5 Firewalls) - 5.9.2.14-13o
• Gen 6 Firewalls - 6.5.2.8-2n (for SM9800, NSsp 12400, and NSsp 12800) and 6.5.4.15.116n (for other Gen 6 Firewall appliances)

The network security vendor has since updated the bulletin to reflect the possibility that it may have been actively exploited.

"This vulnerability is potentially being exploited in the wild," it added. "Please apply the patch as soon as possible for affected products."

As temporary mitigations, it's recommended to restrict firewall management to trusted sources or disable firewall WAN management from Internet access. For SSLVPN, it's advised to limit access to trusted sources, or disable internet access altogether.

Additional mitigations include enabling multi-factor authentication (MFA) for all SSLVPN users using one-time passwords (OTPs) and recommending customers using GEN5 and GEN6 firewalls with SSLVPN users who have locally managed accounts to immediately update their passwords for preventing unauthorized access.

There are currently no details about how the flaw may have been weaponized in the wild, but Chinese threat actors have, in the past, unpatched SonicWall Secure Mobile Access (SMA) 100 appliances to establish long-term persistence.