PHOENIX CONTACT mGuard
Plan Patch8.6ICS-CERT ICSA-17-131-01May 11, 2017
Attack VectorNetwork
Auth RequiredNone
ComplexityLow
User InteractionNone needed
Summary
Phoenix Contact mGuard firmware versions 8.3.0 through 8.4.2 contain input validation and authentication weaknesses (CWE-400 Uncontrolled Resource Consumption, CWE-287 Improper Authentication) that allow remote attackers to cause a denial of service. An attacker can send specially crafted requests or flood the device with traffic, exhausting resources and preventing the mGuard from processing legitimate network traffic. No vendor patch is currently available for affected versions.
What this means
What could happen
An attacker can flood the mGuard device with network packets, causing it to become unresponsive and unable to route traffic or enforce security policies, which would interrupt network connectivity to your protected control systems.
Who's at risk
Industrial facilities using Phoenix Contact mGuard industrial firewalls, particularly those deployed as perimeter security devices protecting PLCs, SCADA networks, or remote access gateways in manufacturing, water, electric, and oil/gas operations.
How it could be exploited
An attacker on the network sends specially crafted or high-volume packets to the mGuard device without needing any credentials. The device fails to properly rate-limit or validate incoming connections, causing a denial of service that stops the device from processing legitimate traffic.
Prerequisites
- Network access to the mGuard device (reachable from attacker's network segment)
- No credentials required
- Ability to send crafted or flood packets to exposed ports
remotely exploitableno authentication requiredlow complexityaffects network availabilityno patch available for affected firmware versions
Exploitability
Low exploit probability (EPSS 0.2%)
Affected products (1)
ProductAffected VersionsFix Status
mGuard: firmware≥ 8.3.0 | ≤ 8.4.2No fix (EOL)
Remediation & Mitigation
0/5
Do now
0/2WORKAROUNDRestrict network access to mGuard management interfaces using firewall rules to allow only trusted engineering and administrative systems
HARDENINGMonitor mGuard CPU and connection state for signs of resource exhaustion; configure alerts for abnormal connection spikes
Schedule — requires maintenance window
0/3Patching may require device reboot — plan for process interruption
HARDENINGIsolate mGuard on a dedicated management network segment separate from production control system traffic
HARDENINGReview and test failover procedures in case mGuard becomes unresponsive during an attack
HOTFIXContact Phoenix Contact for security patches or firmware updates if they become available
CVEs (2)
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