EOL Sophos firewalls get hotfix for old but still exploited vulnerability (CVE-2022-3236)

Over a year has passed since Sophos delivered patches for a vulnerability affecting Sophos Firewalls (CVE-2022-3236) that was being actively exploited by attackers, and now they have pushed additional ones to protect vulnerable EOL devices.

EOL Sophos firewalls CVE-2022-3236

“In December 2023, we delivered an updated fix after identifying new exploit attempts against this same vulnerability in older, unsupported versions of the Sophos Firewall,” the company shared on Monday by updating of the original security advisory.

“No action is required if organizations have upgraded their firewalls to a supported firmware version after September 2022. We immediately developed a patch for certain EOL firmware versions, which was automatically applied to the 99% of affected organizations that have ‘accept hotfix’ turned on. All the vulnerable devices are running end-of-life (EOL) firmware.”

Fixes and workarounds

CVE-2022-3236 is a code injection vulnerability in the User Portal and Webadmin of Sophos Firewall that allows for remote code execution on the targeted vulnerable installation.

Sophos has now released hotfixes to fix CVE-2022-3236 on EOL Sophos firewalls running the following firmware versions:

  • v19.0 GA, MR1, and MR1-1
  • v18.5 GA, MR1, MR1-1, MR2, MR3, and MR4
  • v17.0 MR10

Admins of EOL devices that don’t have the “accept hotfix” option turned on must download and apply the hotfix manually. (The option is enabled by default, but can be disabled.)

If they can’t install the hotfixes, customers can disable WAN access to the User Portal and Webadmin and switch to using VPN and/or Sophos Central for remote access and management.

Customers can verify whether the hotfix has been installed on their devices by following the steps outlined here.

Just how many internet-facing, vulnerable EOL devices are still out there is difficult to say.

Earlier this year, VulnCheck found over 4,000 after scanning the internet, and provided a set of indicators that can point to exploitation attempts.

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