Full Report
SENTRON PAC3200 only provide a 4-digit PIN to protect from administrative access via Modbus TCP interface. Attackers with access to the Modbus TCP interface could easily bypass this protection by brute-force attacks or by monitoring the Modbus cleartext communication. Siemens recommends specific countermeasures for products where fixes are not, or not yet available.
Analysis Summary
# Vulnerability: Weak 4-Digit PIN Protection on SENTRON PAC3200 via Modbus TCP
## CVE Details
- CVE ID: CVE-2024-41798
- CVSS Score: 9.8 (Critical) (v3.1) / 9.3 (Critical) (v4.0)
- CWE: CWE-287: Improper Authentication
## Affected Systems
- Products: SENTRON 7KM PAC3200
- Versions: All versions affected.
- Configurations: When administrative access is attempted via the Modbus TCP interface.
## Vulnerability Description
The SENTRON PAC3200 devices use only a 4-digit PIN to protect administrative access over the Modbus TCP interface. An attacker who has access to the Modbus TCP interface can easily bypass this protection mechanism through brute-force attacks against the weak PIN or by monitoring the cleartext Modbus communication to capture credentials.
## Exploitation
- Status: PoC available (Implied by ease of brute-force/sniffing)
- Complexity: Low (Brute force feasible against 4 digits, cleartext communication allows sniffing)
- Attack Vector: Network (Requires access to the Modbus TCP interface)
## Impact
- Confidentiality: High (Attackers can likely access sensitive configuration/system data via administrative access)
- Integrity: High (Attackers can likely modify device settings via administrative access)
- Availability: High (Potential ability to disrupt operations via administrative access)
## Remediation
### Patches
- Currently, no fix is planned for the vulnerable product (SENTRON PAC3200).
### Workarounds
- **PIN Reassessment:** Consider the 4-digit PIN as protection only against unauthorized *operation* (inadvertent errors), not as protection against malicious access attempts (like brute-force attacks).
- **Network Segmentation:** Implement strong network access controls to restrict who can reach the Modbus TCP interface.
- **Follow Security Guidelines:** Configure the environment according to Siemens' operational guidelines for Industrial Security and product manuals.
## Detection
- **Indicators of Compromise:** Unusual high volume of Modbus TCP connection attempts or authentication failures, or unexpected configuration changes originating from Modbus traffic.
- **Detection Methods and Tools:** Monitoring Modbus TCP traffic for cleartext credentials (if applicable to the specific management functions) and network intrusion detection systems (NIDS) monitoring for brute-force patterns targeting the Modbus authentication mechanism.
## References
- Vendor Advisories: SSA-850560 (siemens dot com/cert/advisories)
- Relevant Links:
- Siemens Security Advisory portal: hxxps://cert-portal.siemens.com/productcert/html/ssa-850560.html
- FAQ Article: hxxps://support.industry.siemens.com/cs/ww/en/view/109975235/
- Operational Guidelines: hxxps://www.siemens.com/cert/operational-guidelines-industrial-security