Siemens SIMATIC S7-1200 CPU V1/V2 Devices
As of January 10, 2023, CISA will no longer be updating ICS security advisories for Siemens product vulnerabilities beyond the initial advisory. For the most up-to-date information on vulnerabilities in this advisory, please see Siemens’ ProductCERT Security Advisories (CERT Services | Services | Siemens Global).
1. EXECUTIVE SUMMARY
- CVSS v4 8.7
- ATTENTION: Exploitable remotely/low attack complexity
- Vendor: Siemens
- Equipment: SIMATIC S7-1200 CPU V1/V2 Devices
- Vulnerabilities: Improper Input Validation, Authentication Bypass by Capture-replay
2. RISK EVALUATION
Successful exploitation of these vulnerabilities could allow an unauthenticated remote attacker to trigger functions by record and playback of legitimate network communication, or place the controller in stop/defect state by causing a communications error.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
Siemens reports that the following products are affected:
- SIMATIC S7-1200 CPU V1 family (incl. SIPLUS variants): All versions before 2.0.3 (CVE-2011-20001)
- SIMATIC S7-1200 CPU V1 family (incl. SIPLUS variants): All versions before 2.0.2 (CVE-2011-20002)
- SIMATIC S7-1200 CPU V2 family (incl. SIPLUS variants): All versions before 2.0.3 (CVE-2011-20001)
- SIMATIC S7-1200 CPU V2 family (incl. SIPLUS variants): All versions before 2.0.2 (CVE-2011-20002)
3.2 VULNERABILITY OVERVIEW
3.2.1 IMPROPER INPUT VALIDATION CWE-20
The web server interface of affected devices improperly processes incoming malformed HTTP traffic at high rate. This could allow an unauthenticated remote attacker to force the device entering the stop/defect state, thus creating a denial-of-service condition.
CVE-2011-20001 has been assigned to this vulnerability. A CVSS v3.1 base score of 7.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
A CVSS v4 score has also been calculated for CVE-2011-20001. A base score of 8.7 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N).
3.2.2 AUTHENTICATION BYPASS BY CAPTURE-REPLAY CWE-294
Affected controllers are vulnerable to capture-replay in the communication with the engineering software. This could allow an on-path attacker between the engineering software and the controller to execute any previously recorded commands at a later time (e.g. set the controller to STOP), regardless whether or not the controller had a password configured.
CVE-2011-20002 has been assigned to this vulnerability. A CVSS v3.1 base score of 7.4 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H).
A CVSS v4 score has also been calculated for CVE-2011-20002. A base score of 8.3 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N).
3.3 BACKGROUND
- CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
- COUNTRIES/AREAS DEPLOYED: Worldwide
- COMPANY HEADQUARTERS LOCATION: Germany
3.4 RESEARCHER
Artem Zinenko from Kaspersky and Dillon Beresford from NSS Labs reported these vulnerabilities to Siemens.
4. MITIGATIONS
Siemens has released new versions for the affected products and recommends updating to the latest versions:
- (CVE-2011-20001): Disable the web server if possible
- (CVE-2011-20001): Update to V2.0.3 or later version
- (CVE-2011-20002): Update to V2.0.2 or later version
As a general security measure, Siemens recommends protecting network access to devices with appropriate mechanisms. To operate the devices in a protected IT environment, Siemens recommends configuring the environment according to Siemens’ operational guidelines for industrial security and following recommendations in the product manuals.
Additional information on industrial security by Siemens can be found on the Siemens industrial security webpage.
For more information see the associated Siemens security advisory SSA-625789 in HTML and CSAF.
CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities, such as:
- Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
- Locate control system networks and remote devices behind firewalls and isolating them from business networks.
- When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs). Recognize VPNs may have vulnerabilities, should be updated to the most recent version available, and are only as secure as the connected devices.
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 cisa.gov. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.
CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.
Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov in the technical information paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.
Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.
No known public exploitation specifically targeting these vulnerabilities has been reported to CISA at this time.
5. UPDATE HISTORY
- October 21, 2025: Initial Republication of Siemens ProductCERT SSA-625789