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1. EXECUTIVE SUMMARY
- CVSS v3 3.1
- ATTENTION: Exploitable remotely/low skill level to exploit
- Vendor: Siemens
- Equipment: SIMATIC, SIMOTICS
- Vulnerability: TOCTOU Race Condition
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow an attacker to read a discrete set of traffic over the air after a Wi-Fi device state change.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following Siemens products are affected:
- SIMATIC RF350M: All versions
- SIMATIC RF650M: All versions
- SIMOTICS CONNECT 400: All versions
3.2 VULNERABILITY OVERVIEW
3.2.1 TIME-OF-CHECK TIME-OF-USE (TOCTOU) RACE CONDITION) CWE-367
Specially timed and crafted traffic can cause internal errors (related to state transitions) in a WLAN device that can lead to improper Layer 2 Wi-Fi encryption and information disclosure over the air for a discrete set of traffic. This issue was discovered on Broadcom Wi-Fi client devices.
CVE-2019-15126 has been assigned to this vulnerability. A CVSS v3 base score of 3.1 has been calculated; the CVSS vector string is (AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N).
3.3 BACKGROUND
- CRITICAL INFRASTRUCTURE SECTORS: Energy
- COUNTRIES/AREAS DEPLOYED: Worldwide
- COMPANY HEADQUARTERS LOCATION: Germany
3.4 RESEARCHER
Siemens reported this vulnerability to CISA.
4. MITIGATIONS
Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk:
- SIMATIC RF350M and RF650M: Disable Wi-Fi, if possible
- SIMOTICS CONNECT 400: No specific countermeasures needed as the data is protected via TLS on application layer
As a general security measure, Siemens strongly recommends protecting network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends configuring the environment according to the Siemens operational guidelines for Industrial Security and following the recommendations in the product manuals.
For additional information, please refer to Siemens Security Advisory SSA-712518
CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.
CISA also provides a section for control systems security recommended practices on the ICS webpage on us-cert.gov. Several recommended practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.
Additional mitigation guidance and recommended practices are publicly available on the ICS webpage on us-cert.gov in the Technical Information Paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies.
Organizations observing any suspected malicious activity should follow their established internal procedures and report their findings to CISA for tracking and correlation against other incidents.
No known public exploits specifically target this vulnerability.
Contact Information
For any questions related to this report, please contact the CISA at:
Email: CISAservicedesk@cisa.dhs.gov
Toll Free: 1-888-282-0870
For industrial control systems cybersecurity information: https://www.us-cert.gov/ics
or incident reporting: https://www.us-cert.gov/report
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