CVE-2022-50926: WAGO PFC200 Privilege Escalation Flaw

CVE-2022-50926 Overview

CVE-2022-50926 is a privilege escalation vulnerability affecting the WAGO 750-8212 PFC200 G2 2ETH RS firmware. This vulnerability allows attackers to manipulate user session cookies, specifically by modifying the cookie's name and roles parameters to elevate from ordinary user to administrative privileges without proper authentication.

The vulnerability stems from CWE-565: Reliance on Cookies without Validation and Integrity Checking. The affected firmware fails to properly validate the integrity of session cookie values, enabling attackers to craft malicious cookies that grant unauthorized administrative access to the programmable logic controller (PLC) web management interface.

Critical Impact

Attackers with low-level access can escalate to full administrative privileges on industrial control systems by manipulating session cookies, potentially compromising critical infrastructure operations.

Affected Products

• WAGO 750-8212 PFC200 G2 2ETH RS firmware
• WAGO PFC200 series controllers with vulnerable firmware versions
• Industrial control systems utilizing affected WAGO PLC devices

Discovery Timeline

• 2026-01-13 - CVE CVE-2022-50926 published to NVD
• 2026-01-13 - Last updated in NVD database

Technical Details for CVE-2022-50926

Vulnerability Analysis

This privilege escalation vulnerability exists due to improper validation of client-side session cookie values within the WAGO PFC200 firmware's web management interface. The firmware relies on cookie parameters such as name and roles to determine user access levels without performing adequate server-side validation or integrity checking.

When a user authenticates to the PLC's web interface, the system issues session cookies containing user identity and role information. Due to the lack of cryptographic signing or server-side session state verification, an attacker with network access can intercept and modify these cookies. By changing the roles parameter value to indicate administrative privileges, the attacker effectively bypasses the authorization mechanism.

This type of vulnerability is particularly concerning in industrial control system (ICS) environments where PLCs like the WAGO PFC200 series manage critical operational technology (OT) processes. Unauthorized administrative access could enable attackers to modify PLC configurations, disrupt industrial processes, or pivot to other network-connected systems.

Root Cause

The root cause of this vulnerability is the firmware's reliance on client-controlled cookie values for authorization decisions without proper validation and integrity checking (CWE-565). The session management implementation trusts the name and roles parameters transmitted by the client without verifying them against server-side session storage or cryptographic signatures.

This architectural flaw allows any authenticated user—or potentially an unauthenticated attacker with access to cookie values—to forge session tokens with elevated privileges. The absence of secure session token generation and verification mechanisms is the fundamental weakness exploited by this vulnerability.

Attack Vector

The attack is network-based and can be executed by any user with low-level access to the WAGO PFC200 web interface. The exploitation process involves:

1. An attacker authenticates to the PLC web interface with a low-privilege account or obtains a valid session cookie
2. The attacker intercepts or examines the session cookie containing name and roles parameters
3. Using browser developer tools or a proxy tool, the attacker modifies the roles parameter to specify administrative privileges
4. The modified cookie is sent with subsequent requests, granting the attacker administrative access
5. With administrative privileges, the attacker can modify PLC configurations, access sensitive data, or disrupt operations

This attack requires network access to the target device and low-level authenticated access, making it exploitable in scenarios where an attacker has gained initial foothold on the OT network or where guest/operator accounts exist.

Detection Methods for CVE-2022-50926

Indicators of Compromise

• Unexpected administrative actions performed by non-administrative user accounts in PLC audit logs
• Session cookies with modified or inconsistent roles parameter values compared to authenticated user permissions
• Multiple privilege level changes within a single session without re-authentication events
• Unusual configuration changes or access patterns from IP addresses associated with low-privilege users

Detection Strategies

• Implement network monitoring to detect anomalous traffic patterns to WAGO PLC web interfaces
• Deploy web application firewalls (WAF) or ICS-specific security appliances to inspect and validate session cookie integrity
• Enable and centralize logging from WAGO PLC devices to detect privilege escalation attempts
• Utilize intrusion detection systems (IDS) with signatures for cookie manipulation attacks against industrial control systems

Monitoring Recommendations

• Continuously monitor administrative activity on WAGO PLC devices for unauthorized configuration changes
• Implement network segmentation monitoring to detect lateral movement attempts from compromised PLCs
• Establish baseline behavior profiles for PLC web interface access and alert on deviations
• Integrate WAGO device logs with SIEM platforms for correlation with other security events

How to Mitigate CVE-2022-50926

Immediate Actions Required

• Restrict network access to WAGO PFC200 web management interfaces using firewall rules and network segmentation
• Implement strong authentication mechanisms and limit the number of user accounts with access to PLC interfaces
• Place affected devices behind VPN access controls to reduce exposure
• Audit existing user accounts and remove unnecessary or guest accounts from PLC configurations

Patch Information

Organizations should consult WAGO's official website for firmware updates addressing this vulnerability. Review the VulnCheck Advisory for additional guidance on affected versions and remediation steps. Technical details about the exploitation method are available via Exploit-DB #50793.

Workarounds

• Implement network segmentation to isolate WAGO PLCs from general IT networks and untrusted zones
• Use reverse proxy solutions with additional authentication layers in front of PLC web interfaces
• Disable the web management interface if not required for operations
• Deploy network-level access controls (ACLs) to limit which hosts can communicate with PLC management ports
• Consider implementing application-layer gateways that can validate session integrity before forwarding requests to PLCs