CVE-2022-3713: Sophos XG Firewall Firmware RCE Flaw

CVE-2022-3713 Overview

CVE-2022-3713 is a code injection vulnerability affecting the Wifi controller component of Sophos Firewall releases older than version 19.5 GA. This vulnerability allows adjacent network attackers to execute arbitrary code on affected devices without requiring authentication or user interaction.

The vulnerability exists in the Wifi controller functionality, enabling attackers on an adjacent network to inject and execute malicious code. Given the critical role that firewalls play in network security infrastructure, exploitation of this vulnerability could lead to complete compromise of network perimeter defenses.

Critical Impact

Adjacent network attackers can achieve code execution on Sophos Firewall devices, potentially leading to complete compromise of network security infrastructure and lateral movement capabilities.

Affected Products

• Sophos XG Firewall Firmware versions prior to 19.5 GA
• Sophos XG Firewall hardware appliances running vulnerable firmware

Discovery Timeline

• December 1, 2022 - CVE-2022-3713 published to NVD
• April 24, 2025 - Last updated in NVD database

Technical Details for CVE-2022-3713

Vulnerability Analysis

CVE-2022-3713 is classified as CWE-94 (Improper Control of Generation of Code), commonly known as Code Injection. This vulnerability class occurs when software constructs code segments using externally-influenced input without proper neutralization of special elements that could modify the intended code behavior.

The vulnerability specifically targets the Wifi controller component within Sophos Firewall. The adjacent network attack vector means an attacker must have access to the same network segment as the vulnerable device, which could include wireless networks managed by the affected firewall or directly connected network segments.

Successful exploitation requires no privileges and no user interaction, making it particularly dangerous in environments where network segmentation is not properly enforced. An attacker who achieves code execution on a firewall device gains a highly privileged position within the network infrastructure, potentially enabling traffic interception, security policy manipulation, and pivot attacks against internal network resources.

Root Cause

The root cause stems from improper input validation and sanitization within the Wifi controller component. When processing certain inputs, the controller fails to properly neutralize code-significant elements, allowing an attacker to inject executable code that the system interprets and runs with elevated privileges.

This type of vulnerability typically arises when user-controlled data is incorporated into dynamically generated code or command strings without adequate escaping or validation mechanisms.

Attack Vector

The attack vector for CVE-2022-3713 requires adjacent network access. This means the attacker must be positioned on the same local network segment as the target Sophos Firewall device. Potential attack scenarios include:

An attacker connected to a wireless network managed by the vulnerable firewall could exploit this vulnerability to gain control of the device. Similarly, an attacker with access to any network segment directly connected to the firewall interface could attempt exploitation.

The attack can be executed without authentication credentials and does not require any action from legitimate users or administrators, significantly lowering the barrier to exploitation.

Detection Methods for CVE-2022-3713

Indicators of Compromise

• Unexpected processes or services running on Sophos Firewall devices
• Anomalous network traffic originating from or destined to the Wifi controller interface
• Unauthorized configuration changes to wireless network settings
• Suspicious log entries related to Wifi controller operations

Detection Strategies

• Monitor Sophos Firewall logs for unusual activity patterns related to Wifi controller operations
• Implement network segmentation monitoring to detect unauthorized adjacent network access attempts
• Deploy intrusion detection systems with signatures for code injection attack patterns targeting network appliances
• Conduct regular firmware version audits to identify unpatched devices

Monitoring Recommendations

• Enable verbose logging on Sophos Firewall devices and forward logs to a centralized SIEM solution
• Monitor for unexpected outbound connections from firewall management interfaces
• Implement network traffic analysis to detect anomalous patterns in Wifi controller communications
• Establish baseline behavior profiles for firewall devices and alert on deviations

How to Mitigate CVE-2022-3713

Immediate Actions Required

• Upgrade Sophos Firewall to version 19.5 GA or later immediately
• Restrict adjacent network access to firewall management and Wifi controller interfaces
• Implement network segmentation to limit potential attacker positioning
• Review firewall configurations for unauthorized changes

Patch Information

Sophos has released a security patch addressing this vulnerability in Sophos Firewall version 19.5 GA. Organizations running older versions should upgrade immediately to address this code injection vulnerability.

For detailed patch information and download links, refer to the Sophos Security Advisory SA-20221201.

Workarounds

• Disable Wifi controller functionality if not required in your environment
• Implement strict network segmentation to limit adjacent network attack surface
• Apply firewall rules to restrict access to Wifi controller management interfaces
• Enable additional monitoring and logging for Wifi controller operations until patching is complete