Hackers Exploited Zero-Day RCE Vulnerability in Sophos Firewall — Patch Released

CVE-2022-1040 is a critical authentication bypass in the User Portal and Webadmin of Sophos Firewall (SFOS) version v18.5 MR3 and older. A remote, unauthenticated attacker who can reach either web-facing service bypasses authentication and executes code on the firewall appliance. Successful exploitation yields full device compromise (CVSS 9.8 with high confidentiality, integrity, and availability impact), enabling traffic interception, persistence, and pivoting into the protected network. Any organization running an affected Sophos Firewall version where the User Portal or Webadmin is reachable, especially from the internet, is exposed. Exploitation is confirmed in the wild: it was exploited as a zero-day in March 2022, added to CISA's Known Exploited Vulnerabilities Catalog on 2022-03-31, and used in campaigns attributed to Chinese actors, including a U.S. indictment of a Chinese hacker for exploiting the flaw.

Do: Upgrade Sophos Firewall to a fixed release (v18.5 MR4 or later, per Sophos' patch instructions). Until patched, restrict access to the User Portal and Webadmin to trusted management networks or VPN clients and remove any direct internet exposure to these services. Review device and authentication logs for signs of exploitation, including unexpected or modified administrator accounts and configuration changes, and follow the vendor/CISA required action to apply updates.

CVE-2022-3236 is a critical (CVSS 9.8) code injection flaw (CWE-94) in the User Portal and Webadmin interfaces of Sophos Firewall version v19.0 MR1 and older. A remote, unauthenticated attacker can send crafted input to an exposed User Portal or Webadmin service, and the network-reachable, no-privilege, no-user-interaction nature of the flaw makes it trivially triggerable once those interfaces are reachable. Successful exploitation results in arbitrary code execution on the firewall appliance, with high impact to confidentiality, integrity, and availability. Any organization running Sophos Firewall v19.0 MR1 or older is affected, including end-of-life appliances for which the vendor issued a dedicated hotfix. The flaw is confirmed exploited in the wild: it was abused as a zero-day before the patch, added to CISA KEV on 2022-09-23, carries a 98.9% EPSS, and news reports indicate it was still being exploited against EOL firewalls well after disclosure.

Do: Upgrade Sophos Firewall to version 19.5 or later per vendor instructions (the fix shipped in the 19.5 release line), and apply the vendor hotfix to end-of-life appliances that cannot upgrade. Restrict internet exposure of the User Portal (TCP 443) and Webadmin (TCP 4444) to trusted management IPs via WAN access rules, and review appliance logs for signs of exploitation. As this CVE is in CISA KEV, federal agencies and other defenders with KEV-driven patch mandates should confirm the update is applied.