WAGO: Controller with CODESYS 2.3 Runtime Denial-of-Service
Monitor4.9VDE-2023-006Jun 25, 2023
Attack VectorNetwork
Auth RequiredHigh
ComplexityLow
User InteractionNone needed
Summary
A denial-of-service vulnerability exists in WAGO Ethernet Controllers (3rd and 4th generation) and PFC200 controllers running CODESYS 2.3 runtime. An authenticated attacker can send a malformed packet to the CODESYS V2 runtime communication port, triggering improper handling of the packet that crashes the device and halts the PLC runtime. The vulnerability requires valid engineering credentials and network access to the controller's CODESYS communication interface. WAGO has released firmware updates to address this issue across all affected product lines.
What this means
What could happen
An authenticated attacker can crash WAGO controllers running CODESYS 2.3 runtime by sending a malformed packet, causing the PLC to stop responding and interrupting any automated processes it controls.
Who's at risk
Organizations operating WAGO Ethernet Controllers (3rd and 4th generation models 750-series) and PFC200 programmable controllers that run CODESYS 2.3 runtime, particularly in water systems, building automation, or distributed I/O applications. Any facility using these PLCs for critical automated processes is at risk of unplanned downtime.
How it could be exploited
An attacker with network access to the CODESYS V2 runtime communication port (default port 502 or configured port) and valid credentials can send a specially crafted packet to the PLC's packet parsing function. This causes an unhandled exception that crashes the runtime, dropping all connections and halting any control logic execution.
Prerequisites
- Network access to the PLC's CODESYS 2 runtime communication port
- Valid PLC engineering credentials or access to a programming workstation
- CODESYS 2 runtime enabled on the device
- Device running affected firmware version
Remotely exploitableRequires authenticationLow complexity attackAffects availability / causes denial of serviceVendor patches availableAffects industrial automation and control systems
Affected products (17)
17 with fix
ProductAffected VersionsFix Status
Ethernet Controller 3rd Generation 750-331≤ FW14FW17 (after BACnet certification)
Ethernet Controller 3rd Generation 750-829≤ FW14FW17 (after BACnet certification)
Ethernet Controller 3rd Generation 750-831/xxx-xxx≤ FW14FW17 (after BACnet certification)
Ethernet Controller 3rd Generation 750-852≤ FW16FW17
Ethernet Controller 3rd Generation 750-880/xxx-xxx≤ FW16FW17
Remediation & Mitigation
0/6
Do now
0/2WORKAROUNDDisable the CODESYS 2 runtime communication port if the PLC runtime is not actively needed via Configuration > PLC Runtime Services > CODESYS 2 > communication enabled in the web management interface
HARDENINGRestrict network access to the PLC and CODESYS communication ports to only authorized engineering workstations and programming networks using firewall rules
Schedule — requires maintenance window
0/3Patching may require device reboot — plan for process interruption
PFC200
HOTFIXUpdate WAGO PFC200 family controllers to firmware version FW22 Patch 2 or later
All products
HOTFIXUpdate WAGO Ethernet Controller 3rd Generation (750-331, 750-829, 750-831, 750-852, 750-880, 750-881, 750-882, 750-885, 750-889) to firmware version FW17
HOTFIXUpdate WAGO Ethernet Controller 4th Generation (750-823, 750-332, 750-832, 750-862, 750-890, 750-891, 750-893) to firmware version FW11
Long-term hardening
0/1HARDENINGIsolate industrial control systems from direct Internet access and untrusted networks; apply defense-in-depth network segmentation
CVEs (2)
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