Tag Archives: Safety Instrument Systems

Triton: Dangerous and Puzzling – Part II

11 March 2017

Part II: Some thoughts on the access vector

For preparation of the attack the attacker had to gain in-depth knowledge about the victim’s network and SIS installation.

SIS installation

According to Schneider Electric such attack could only be successful for Triconex Tricon controllers configured with the model 3008 Main Processor and firmware versions 10.0 to 10.4.(1) Only this controller family seems to use PowerPC processors. Older Tricon controllers use National Semiconductor, newer systems use ARM processors.(2)

Since the binary malware components inject.bin and imain.bin were compiled in PowerPC byte code the attacker hat detailed knowledge about the installation, in particular the controller version. Without this knowledge about the controller version the attack would have failed because of a code mismatch.


If the SIS controller and engineering station are operated in an isolated SIS network this attack is not possible. For remote control, the Remote Access Trojan (RAT) needs to open at least an outgoing connection to its Command and Control server (C&C) outside the production network.

Blocking incoming traffic to SIS network but allowing outgoing traffic from the SIS network to applications, e.g. a historian, in other production network partitions is industry standard (ISA-99). Unfortunately, the latter recommendation is often misunderstood. Instead of opening only connections to dedicated systems / ports in adjacent partitions the security devices are often opened for all outgoing network traffic, sometimes across partitions.

With this, once the RAT is installed on the engineering station a weak implemented industry standard fosters the connection with the attacker’s C&C server.

Attack vector: Compromised Supply Chain

At first sight this sounds like a bad thriller. But it gives some good answers to some important questions.

How did the attacker get the knowledge of the victim’s facilities?

  1. In-depth knowledge of the plant network and the SIS installation can be extracted from documentation stored on the plant operators computer systems or on the Engineering Service Providers (ESP) computer systems.
  2. An ESP network is in general less well protected against cyber-attacks than a highly secured production network.

Conclusion: It is very likely that the attacker compromised the ESP network and the systems used for developing the SIS software.

How could the attacker develop such mature code?

Once the attacker hijacked the ESP network he was able to develop and test his attack framework on a system very similar to the production SIS.

How was the SIS network / engineering station infected?

With the next project update the ESP transferred the compromised code, e.g. by USB stick, to the production network.

Have a great week.

  1. Hand A. Triton Gone Wild | Automation World [Internet]. Automation World. 2018 [cited 2018 Mar 3]. Available from: https://www.automationworld.com/triton-gone-wild
  2. Analyzing the TRITON industrial malware [Internet]. Midnight Blue Labs. 2018 [cited 2018 Mar 5]. Available from: https://www.midnightbluelabs.com/blog/2018/1/16/analyzing-the-triton-industrial-malware

Triton: Dangerous and Puzzling – Part I

4 March 2018

Jim Finkle’s report ‘Hackers halt plant operations in watershed cyber attack’ (1) published on December 14th, 2017 on Reuters made me curious and nervous at the same time.

The report deals with a cyber-attack on Safety Instrumented Systems (SIS). SIS work independently of the Process Control Systems (PCS). They guarantee that the industrial process, e.g. a reactor or a cracker, can be safely shutdown if the PCS can no longer control the process. Since compromising an SIS may cause significant negative effects on people and environment, the most important task in Production IT Security is to prevent cyber-attacks on SIS.

Although the attack was intensively discussed in the media and by security researchers many questions are still open. With this three-part blog series I like to examine some details more closely. A detailed attack analysis gives IT security strategists the chance to derive improved means for protection of SIS.

Part I: Some facts about the Triton attack

Malware naming

FireEye named the malware TRITON (2). Triton is an attack framework created to interact with Schneider Electric Triconex Safety Instrumented Systems. Other sources name the malware TRISIS (3) or HATMAN (4).

Indicators of Compromise

“In the incident, hackers used sophisticated malware to take remote control of a workstation running a Schneider Electric Triconex safety shutdown system, then sought to reprogram controllers used to identify safety issues. Some controllers entered a fail safe mode, which caused related processes to shut down and caused the plant to identify the attack, FireEye said.” (1)

From the FireEye report, we learn: “The attacker gained remote access to an SIS engineering station and deployed the TRITON attack framework to reprogram the SIS controllers. During the incident, some SIS controllers entered a failed safe state, which automatically shutdown the industrial process and prompted the asset owner to initiate an investigation. The investigation found that the SIS controllers initiated a safe shutdown when application code between redundant processing units failed a validation check — resulting in an MP diagnostic failure message.” (2)

With this, the IoC was: A production process was shutdown by the SIS although no indicators for a failure condition were signaled by the PCS.

Preconditions for a successful attack

At least the SIS Engineering Station must be accessible from the network. The FireEye (2) and Dragos (3) report confirmed that this was the case.

The Triconex memory protection key switch must be left in Program mode long enough to allow the attacker to run the attack. The FireEye (2) report confirmed that this was the case:

“The attacker could have caused a process shutdown by issuing a halt command or intentionally uploading flawed code to the SIS controller to cause it to fail. Instead, the attacker made several attempts over a period of time to develop and deliver functioning control logic for the SIS controllers in this target environment. While these attempts appear to have failed due one of the attack scripts’ conditional checks, the attacker persisted with their efforts.”

The code is publicly available from GitHub. (5)

Threat Actor

From the FireEye (2) and Dragos (3) analysis it is clear, that this was a sophisticated attack. In-depth knowledge of Schneider Electric Triconex SIS and network intrusion technology is required to perform such kind of attack and stay undetected for a while. This indicates a state-sponsored threat actor.

What does this really mean?

Production Network Reference Architecture

Production Network Reference Architecture

The cyber attacker worked his way through the business DMZ, the business network, the production DMZ and the production partition 1 to the SIS engineering station in zone 2 of production partition 2, without being noticed by any security device, SIEM or endpoint protection. That is truly amazing.

It seems like some basic protective measures were either not fully in place or misconfigured or no one checked the logs regarding IoC and IoA.


From my point of view this sounds very unlikely and mysterious. I will present some alternative access scenarios in part II.

Have a good weekend.

  1. Finkle J. Hackers halt plant operations in watershed cyber attack. Reuters [Internet]. 2018 Dec 14 [cited 2018 Feb 4]; Available from: https://www.reuters.com/article/us-cyber-infrastructure-attack/hackers-shut-down-infrastructure-safety-system-in-attack-fireeye-idUSKBN1E8271

  2. Caban D, Krotofil M, Scali D, Brubacker N, Glyer C, Johnson B. Attackers Deploy New ICS Attack Framework “TRITON” and Cause Operational Disruption to Critical Infrastructure [Internet]. FireEye Threat Research Blog. 2017 [cited 2018 Feb 12]. Available from: https://www.fireeye.com/blog/threat-research/2017/12/attackers-deploy-new-ics-attack-framework-triton.html

  3. TRISIS-01.pdf [Internet]. [cited 2018 Mar 3]. Available from: https://dragos.com/blog/trisis/TRISIS-01.pdf

  4. MAR-17-352-01 HatMan—Safety System Targeted Malware_S508C.pdf [Internet]. [cited 2018 Mar 3]. Available from: https://ics-cert.us-cert.gov/sites/default/files/documents/MAR-17-352-01%20HatMan%E2%80%94Safety%20System%20Targeted%20Malware_S508C.pdf

  5. ICSrepo. TRISIS-TRITON-HATMAN: Repository containting original and decompiled files of TRISIS/TRITON/HATMAN malware [Internet]. 2018 [cited 2018 Feb 5]. Available from: https://github.com/ICSrepo/TRISIS-TRITON-HATMAN

Software failures are systematic. Stop all patching?

22 January 2017

In the past days I reviewed the draft of the NAMUR Worksheet NA 163 “IT Risk Assessment for Safety Instrument Systems”. In the age of the IIoT even Safety Instrument Systems (SIS) are equipped with embedded IT components and attached to the production or company network. With this, the safety systems become the target of IT threats, which may result in a malfunction of the SIS in the worst case.

Process safety engineers are often unaware of this new threats. IEC 61511 “Functional safety – Safety instrumented systems for the process industry sector” requires an IT risk assessment for SIS, but makes no recommendations about the details of the assessment.

The aim of Worksheet NA 163 is to provide a practicable risk assessment method to safety engineers, supplemented by a checklist on possible mitigation measures.

On Thursday I watched a video recording of a lecture on ‘Safety-Critcial Systems’ given by Martyn Thomas, Livery Company Professor of Information Technology at the Gresham College.

Software failures are systematic. Slide 18 of 'Safety-Critical Systems - when software is a matter of life and death' by Martyn Thomas CBE FREng, Livery Company Professor of Information Technology, Gresham College

Software failures are systematic. Slide 18 of ‘Safety-Critical Systems – when software is a matter of life and death’ by Martyn Thomas CBE FREng, Livery Company Professor of Information Technology, Gresham College

Professor Thomas makes clear, that “Software failures are systematic. They occur whenever the triggering conditions arise”. I highly recommend to watch the entire lecture because one can gain new insights on software testing and reliability. For a link to the video, the PowerPoint presentation and the Word transcript please see below.

NA 163 recommends to patch all SIS systems components including the supporting systems like the engineering stations or the HMI on a regular basis.

But will continuous patching really increase the reliability of the software components?

Will continuous patching really decrease the risk of a cyber-attack?

How many new systematic defects are built in a software system during continuous patching?

Remember the seemingly endless number of critical vulnerabilities fixed in Adobe Flash Player in the past years…

Let me be clear: I do not call to stop all patching. From my point of view we must focus on the right and important system components, vulnerabilities and patches. With this we can escape from the patch treadmill and focus on the really important issues, e.g. how to build and configure industrial control system networks that are less susceptible to cyber-attacks.

Have a good weekend!

Safety-Critical Systems – when software is a matter of life and death

Martyn Thomas CBE FREng, Livery Company Professor of Information Technology, Gresham College, 10 January 2017

Word Transcript | PowerPoint Presentation | YouTube Video