Full Report
TIM 4R-IE devices contain multiple vulnerabilities in the integrated NTP component as listed below. Siemens recommends specific countermeasures for products where fixes are not, or not yet available.
Analysis Summary
# Vulnerability: Multiple NTP Vulnerabilities in TIM 4R-IE Devices
## CVE Details
- **CVE IDs:**
- CVE-2015-5219, CVE-2015-7705, CVE-2015-7855, CVE-2015-7871, CVE-2015-7973, CVE-2015-7974, CVE-2015-7977, CVE-2015-7979, CVE-2015-8138, CVE-2016-1547, CVE-2016-1548, CVE-2016-1550, CVE-2016-4953, CVE-2016-4954
- **CVSS Score:** Up to 9.8 (Critical)
- **CWEs:** CWE-681, CWE-400, CWE-20, CWE-294, CWE-821, CWE-200, CWE-290, CWE-287, CWE-362
## Affected Systems
- **Products:**
- TIM 4R-IE (incl. SIPLUS NET variants)
- SIPLUS NET TIM 4R-IE (6AG1800-4BA00-7AA0)
- TIM 4R-IE (6NH7800-4BA00)
- TIM 4R-IE DNP3 (incl. SIPLUS NET variants)
- SIPLUS NET TIM 4R-IE DNP3 (6AG1803-4BA00-7AA0)
- TIM 4R-IE DNP3 (6NH7803-4BA00)
- **Versions:** All versions are affected.
- **Configurations:** Systems utilizing the integrated NTP (Network Time Protocol) component for time synchronization.
## Vulnerability Description
The integrated NTP component in Siemens TIM 4R-IE devices contains multiple historical vulnerabilities ranging from 2015 to 2016. These flaws include:
- **Denial of Service (DoS):** Triggered via spoofed packets, crypto-NAKs, or memory exhaustion (e.g., CVE-2016-4953, CVE-2015-7705).
- **Authentication Bypass/Spoofing:** Ability to demobilize associations or spoof packets to change time settings (e.g., CVE-2016-1548).
- **Information Disclosure:** Recovery of message digest keys or peer variables (e.g., CVE-2016-1550).
- **Logic Flaws:** Integrity issues such as "Leap Smearing" issues and unauthorized time adjustments.
## Exploitation
- **Status:** PoC available for several identified NTP vulnerabilities; known historical exploitation of NTP flaws in general.
- **Complexity:** Low to Medium.
- **Attack Vector:** Network.
## Impact
- **Confidentiality:** Low (Some info disclosure).
- **Integrity:** Low to Medium (Unauthorized time changes).
- **Availability:** High (Device/Service DoS).
## Remediation
### Patches
- **No patches planned:** Siemens has stated that no fixes are currently planned for these legacy TIM 4R-IE components.
### Workarounds
- **Network Segmentation:** Minimize network exposure for all control system devices and systems.
- **Firewalling:** Ensure they are not accessible from the Internet. Locate control system networks and remote devices behind firewalls and isolate them from the business network.
- **VPN:** If remote access is required, use secure methods such as Virtual Private Networks (VPNs), recognizing that VPNs may have their own vulnerabilities.
- **NTP Best Practices:** Only allow NTP traffic from trusted time sources and use authenticated NTP where possible.
## Detection
- **Indicators of Compromise:** Unexpected time shifts on the TIM 4R-IE module; high volumes of NTP traffic; logs indicating "crypto-NAK" errors or rapid association/disassociation.
- **Detection methods:** Monitor network traffic for unusual NTP control packets (mode 6/7) using IDS/IPS signatures tuned for NTP vulnerabilities.
## References
- **Vendor Advisory:** hxxps://cert-portal.siemens[.]com/productcert/pdf/ssa-497656.pdf
- **Siemens ProductCERT:** hxxps://www.siemens[.]com/cert/advisories
- **Terms of Use:** hxxps://www.siemens[.]com/productcert/terms-of-use