Use of 4-Digit PIN in SENTRON PAC3200 Devices
Act Now9.8SSA-850560Oct 8, 2024
Attack VectorNetwork
Auth RequiredNone
ComplexityLow
User InteractionNone needed
Summary
SENTRON 7KM PAC3200 power monitoring devices use only a 4-digit PIN to protect administrative access via the Modbus TCP interface. The PIN protection is weak and can be bypassed through brute-force attacks or by capturing cleartext Modbus TCP traffic on the network. An attacker who reaches the Modbus TCP interface can gain administrative control of the device.
What this means
What could happen
An attacker with network access to the Modbus TCP interface can bypass the weak PIN protection and gain administrative control of the PAC3200, allowing them to modify power measurements, disable alarms, alter load-shedding triggers, or disrupt monitoring of electrical systems.
Who's at risk
Electrical utility operators and industrial facilities using SENTRON 7KM PAC3200 power monitoring devices should be concerned. These devices are typically deployed to monitor high-voltage distribution systems, transformer loads, and power quality. If compromised, an attacker can alter power monitoring data and disable protective alarms, impacting grid stability and equipment protection.
How it could be exploited
An attacker with network access to the Modbus TCP port (502) on the PAC3200 can brute-force the 4-digit PIN (10,000 possible combinations) or sniff the PIN from unencrypted Modbus TCP traffic on the network. Once authenticated, the attacker can issue administrative commands to the device.
Prerequisites
- Network access to Modbus TCP port 502 on the PAC3200 device
- Ability to capture or brute-force a 4-digit numeric PIN
remotely exploitableno authentication required for initial accesslow complexity attack (brute-force)no patch availablecleartext communication allows credential captureaffects electrical system monitoring
Exploitability
Low exploit probability (EPSS 0.0%)
Affected products (1)
ProductAffected VersionsFix Status
SENTRON 7KM PAC3200All versionsNo fix (EOL)
Remediation & Mitigation
0/5
Do now
0/1HARDENINGRestrict network access to the Modbus TCP interface (port 502) on all PAC3200 devices using firewall rules. Allow only authorized engineering workstations and SCADA systems to communicate with the device.
Schedule — requires maintenance window
0/2Patching may require device reboot — plan for process interruption
HARDENINGDeploy a network IDS/IPS or firewall capable of inspecting Modbus TCP traffic to detect and block brute-force attempts or unauthorized administrative commands.
HARDENINGMonitor Modbus TCP traffic to and from PAC3200 devices for suspicious patterns, such as repeated failed authentication attempts or cleartext PIN capture.
Mitigations - no patch available
0/2SENTRON 7KM PAC3200 has reached End of Life. The vendor will not release a patch. Apply the following compensating controls:
HARDENINGImplement network segmentation to isolate PAC3200 devices on a separate OT network or VLAN with restricted ingress/egress rules.
HARDENINGFollow Siemens operational guidelines for Industrial Security to harden the overall IT environment and implement defense-in-depth controls around PAC3200 deployment.
CVEs (1)
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