18 August 2019
Pierluigi Paganini’s post (1) on Rogue 7, which popped-up in my LinkedIn news feed last Tuesday, immediately caught my attention. And troubled me somewhat because I am living a mile north from one of the largest German chemical industrial parks where lots of Simatic S7-1200 and S7-1500 PLCs are in operations.
A group of Israeli security researchers managed to compromise PLCs of the Simatic S7-1200 and S7-1500 series. They presented the results at the Black Hat 2019 (2). For more technical details see the accompanying conference paper (3).
The SIMATIC developers learned from the past attacks on the S7 protocol, and integrated cryptographic protection in the latest version of the protocol. This includes a key exchange protocol for secure session set-up between the TIA and the PLC, message integrity protection, and payload encryption.
The Israeli researchers re-engineered the protocol and found some design weaknesses in the implementation which they used to execute start/stop attacks on the PLC, program download and stealth program injection attacks.
To fix the design flaws in the protocol will take some time.
With CPU access protection (4), the design weaknesses can be mitigated. Unfortunately, the default is “No Protection”, that is,” the hardware configuration and the blocks can be read and changed by all users”. So, it’s time to switch CPU access protection on, at least for high risk environments, e.g. if the PLC is directly accessible from the internet and port 102 is open.
Should we be concerned, or, to put in another way: Who should be concerned?
That depends on the target industry and the threat actor.
IEC 62443 request’s that PLCs should be isolated in a separate network zone inside the SCADA partition of the production network. In the best case, communication is allowed from systems in the SCADA partition to the PLC only. If the operator follows this defense in depth strategy during production network build the risk of Rogue 7 style attack on a PLC is low.
Fortunately, operators of critical infrastructures are forced by regulations to implement a defense in depth strategy. But the effort for implementation and operation of an IEC 62443 compliant network is high. To reduce the effort, even large deviations from the IEC 62443 requirements are accepted.
State guided or sponsored threat actors, also called APT (Advanced Persistent Threat), and to a certain extent Organized Crime leverage these deviations in attacks on critical infrastructures. Hacktivists and Script Kiddies can be neglected because they lack the specific network infiltration and SIMATIC S7 know how.
Recall Triton, the attack on a Schneider Electric Triconex safety controller in 2017. The attackers (APT) compromised the Petro Rabigh corporate network in 2014. “From there, they eventually found a way into the plant’s own network, most likely through a hole in a poorly configured digital firewall that was supposed to stop unauthorized access.”(5)
In June 2017, the first unplanned shutdown of a safety controller took place. Finally, on Aug. 4, 2017, at 7:43 p.m., two safety controllers brought parts of the Petro Rabigh complex offline to prevent a gas release and explosion.(6)
The attackers compromised also the PLC. “But as safety devices took extraordinary steps, control room engineers working the weekend shift spotted nothing out of the ordinary, either on their computer screens or out on the plant floor.”(6)
This describes exactly the result of the Rogue 7 program download and stealth program injection attack. The PLC runs the malicious code while the operator believes that everything is in order.
Other production environments.
The S7 protocol uses port 102 for accessing the PLC from the TIA portal, the HMI and the engineering station. The Rouge TIA or the Rogue Engineering station must connect to this port on the PLC for running the start/stop attack or the program download attack. If this port is accessible from the network, in the worst case from the internet, APTs and Organized Crime can easily compromise the PLCs. The risk that Hacktivists or Script Kiddies compromise PLCs is low because they lack of the very specific SIMATIC S7 know how.
How big is the problem? A quick check on Shodan (query: SIMATIC CPU-1200, executed 8/18/2019) shows that about 350 S7-1200 systems are directly connected to the internet, thereof only few with Port 102 open. So, no reason to panic. Most of the operators have already implemented the Siemens recommendations on ICS security.
I welcome the fact that the Israeli security researchers published the weaknesses in the S7 protocol. We can assume, that, like EternalBlue, these weaknesses are already available in stand-by in the arsenals of intelligence agencies around the globe. So, we can prepare for the next leak and, hopefully, prevent a future attack of WannaCry extent.
Direct actions are required to evaluate the current risk.
- Check the firewall rule base to make sure, that the S7 protocol port 102 is not open for systems outside the SCADA network partition or the internet.
- Evaluate the risk of activating CPU access protection. If acceptable, update your operating procedures, train the staff, and active CPU access protection.
For critical infrastructure operators.
- Document every deviation from the IEC 62443 concept. Evaluate the risk with regards to the capabilities of APT and Organized Crime. Take effective protective means if the risk is not acceptable.
Have a great week.
- Paganini P. Boffins hacked Siemens Simatic S7, most secure controllers in the industry [Internet]. Security Affairs. 2019 [cited 2019 Aug 16]. Available from: https://securityaffairs.co/wordpress/89720/hacking/siemens-simatic-s7-hack.html
- Biham E, Bitan S, Carmel A, Dankner A, Malin U, Wool A. PPT: Rogue7: Rogue Engineering-Station attacks on S7 Simatic PLCs [Internet]. Powerpoint Presentation presented at: Black Hat USA 2019; 2019 Aug 8 [cited 2019 Aug 16]; Mandalay Bay / Las Vegas. Available from: https://i.blackhat.com/USA-19/Thursday/us-19-Bitan-Rogue7-Rogue-Engineering-Station-Attacks-On-S7-Simatic-PLCs.pdf
- Biham E, Bitan S, Carmel A, Dankner A, Malin U, Wool A. Rogue7: Rogue Engineering-Station attacks on S7 Simatic PLCs. In Mandalay Bay / Las Vegas; 2019 [cited 2019 Aug 16]. Available from: https://i.blackhat.com/USA-19/Thursday/us-19-Bitan-Rogue7-Rogue-Engineering-Station-Attacks-On-S7-Simatic-PLCs-wp.pdf
- Siemens AG. Simatic S7-1500 Security [Internet]. Siemens AG; 2013 [cited 2019 Aug 16]. Available from: https://www.automation.siemens.com/salesmaterial-as/interactive-manuals/getting-started_simatic-s7-1500/documents/EN/sec_en.pdf
- Giles M. Triton is the world’s most murderous malware, and it’s spreading [Internet]. MIT Technology Review. 2019 [cited 2019 May 11]. Available from: https://www.technologyreview.com/s/613054/cybersecurity-critical-infrastructure-triton-malware/
- Sobczak B. SECURITY: The inside story of the world’s most dangerous malware [Internet]. 2019 [cited 2019 May 11]. Available from: https://www.eenews.net/stories/1060123327