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August 22, 2023

Darktrace’s Detection of Unattributed Ransomware

Leveraging anomaly-based detection, we successfully identified an ongoing ransomware attack on the network of a customer and the activity that preceded it.
Inside the SOC
Darktrace cyber analysts are world-class experts in threat intelligence, threat hunting and incident response, and provide 24/7 SOC support to thousands of Darktrace customers around the globe. Inside the SOC is exclusively authored by these experts, providing analysis of cyber incidents and threat trends, based on real-world experience in the field.
Written by
Natalia Sánchez Rocafort
Cyber Security Analyst
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22
Aug 2023

In the current threat landscape, much of the conversation around ransomware focusses on high-profile strains and notorious threat groups. While organizations and their security teams are justified in these concerns, it is important not to underestimate the danger posed by smaller scale, unattributed ransomware attacks.

Unlike attributed ransomware strains, there are often no playbooks or lists of previously observed indicators of compromise (IoCs) that security teams can consult to help them shore up their cyber defenses. As such, anomaly detection is critical to ensure that emerging threats can be detected based on their abnormality on the network, rather than relying heavily on threat intelligence.

In mid-March 2023, a Darktrace customer requested analytical support from the Darktrace Security Operations Center (SOC) after they had been hit by a ransomware attack a few hours earlier. Darktrace was able to uncover a myriad of malicious activity that preceded the eventual ransomware deployment, ultimately assisting the customer to identify compromised devices and contain the ransomware attack.

Attack Overview

While there were a small number of endpoints that had been flagged as malicious by open-source intelligence (OSINT), Darktrace DETECT™ focused on the unusualness of the activity surrounding this emerging ransomware attack. This provided unparalleled visibility over this ransomware attack at every stage of the cyber kill chain, whilst also revealing the potential origins of the compromise which came months area.

Initial Compromise

Initial investigation revealed that several devices that Darktrace were observed performing suspicious activity had previously engaged in anomalous behavior several months before the ransomware event, indicating this could be a part of a repeated compromise or the result of initial access brokers.

Most notably, in late January 2023 there was a spike in unusual activity when some of the affected devices were observed performing activity indicative of network and device scanning.

Darktrace DETECT identified some of the devices establishing unusually high volumes of internal failed connections via TCP and UDP, and the SMB protocol. Various key ports, such as 135, 139, and 445, were also scanned.

Due to the number of affected devices, the exact initial attack vector is unclear; however, one likely scenario is associated with an internet-facing DNS server. Towards the end of January 2023, the server began to receive unusual TCP DNS requests from the rare external endpoint, 103.203.59[.]3, which had been flagged as potentially malicious by OSINT [4]. Based on a portion of the hostname of the device, dc01, we can assume that this server served as a gateway to the domain controller. If a domain controller is compromised, a malicious actor would gain access to usernames and passwords within a network allowing attackers to obtain administrative-level access to an organization’s digital estate.

Around the same time as the unusual TCP DNS requests, Darktrace DETECT observed the domain controller engaging in further suspicious activity. As demonstrated in Figure 1, Darktrace recognized that this server was not responding to common requests from multiple internal devices, as it would be expected to. Following this, the device was observed carrying out new or uncommon Windows Management Instrumentation (WMI) activity. WMI is typically used by network administrators to manage remote and local Windows systems [3].

Figure 1: Device event log depicting the possible Initial attack vector.


Had Darktrace RESPOND™ been enabled in autonomous response mode, it would have to blocked connections originating from the compromised internal devices as soon as they were detected, while also limiting affected devices to their pre-established patterns of file to prevent them from carrying out any further malicious activity.

Darktrace subsequently observed multiple devices establishing various chains of connections that are indicative of lateral movement activity, such as unusual internal RDP and WMI requests. While there may be devices within an organization that do regularly partake these types of connections, Darktrace recognized that this activity was extremely unusual for these devices.

Darktrace’s Self-Learning AI allows for a deep understanding of customer networks and the devices within them. It’s anomaly-based threat detection capability enables it to recognize subtle deviations in a device’s normal patterns of behavior, without depending on known IoCs or signatures and rules to guide it.

Figure 2: Observed chain of possible lateral movement.


Persistence

Darktrace DETECT observed several affected devices communicating with rare external endpoints that had also been flagged as potentially malicious by OSINT tools. Multiple devices were observed performing activity indicative of NTLM brute-forcing activity, as seen in the Figure 3 which highlights the event log of the aforementioned domain controller. Said domain controller continuously engaged in anomalous behavior throughout the course of the attack. The same device was seen using a potentially compromise credential, ‘cvd’, which was observed via an SMB login event.

Figure 3: Continued unusual external connectivity.


Affected devices, including the domain controller, continued to engage in consistent communication with the endpoints prior to the actual ransomware attack. Darktrace identified that some of these malicious endpoints had likely been generated by Domain Generation Algorithms (DGA), a classic tactic utilized by threat actors. Subsequent OSINT investigation revealed that one such domain had been associated with malware such as TrojanDownloader:Win32/Upatre!rfn [5].

All external engagements were observed by Darktrace DETECT and would have been actioned on by Darktrace RESPOND, had it been configured in autonomous response mode. It would have blocked any suspicious outgoing connections originating from the compromised devices, thus preventing additional external engagement from taking place. Darktrace RESPOND works in tandem with DETECT to autonomously take action against suspicious activity based on its unusualness, rather than relying on static lists of ‘known-bads’ or malicious IoCs.

Reconnaissance

On March 14, 2023, a few days before the ransomware attack, Darktrace observed multiple internal devices failing to establish connections in a manner that suggests SMB, RDP and network scanning. Among these devices once more was the domain controller, which was seen performing potential SMB brute-forcing, representing yet another example of malicious activity carried out by this device.

Lateral Movement

Immediately prior to the attack, many compromised devices were observed mobilizing to conduct an array of high-severity lateral movement activity. Darktrace detected one device using two administrative credentials, namely ‘Administrator’ and ‘administrator’, while it also observed a notable spike in the volume of successful SMB connections from the device around the same time.

At this point, Darktrace DETECT was observing the progression of this attack along the cyber kill chain. What had started as internal recognisance, had escalated to exploitation and ensuing command-and-control activity. Following an SMB brute-force attempt, Darktrace DETECT identified a successful DCSync attack.

A DCSync attack occurs when a malicious actor impersonates a domain controller in an effort to gather sensitive information, such as user credentials and passwords hashes, by replicating directory services [1]. In this case, a device sent various successful DRSGetNCChanges operation requests to the DRSUAPI endpoint.

Data Exfiltration

Around the same time, Darktrace detected the compromised server transferring a high volume of data to rare external endpoints associated with Bublup, a third-party project management application used to save and share files. Although the actors attempted to avoid the detection of security tools by using a legitimate file storage service, Darktrace understood that this activity represented a deviation in this device’s expected pattern of life.

In one instance, around 8 GB of data was transferred, and in another, over 4 GB, indicating threat actors were employing a tactic known as ‘low and slow’ exfiltration whereby data is exfiltrated in small quantities via multiple connections, in an effort to mask their suspicious activity. While this tactic may have evaded the detection of traditional security measures, Darktrace’s anomaly-based detection allowed it to recognize that these two incidents represented a wider exfiltration event, rather than viewing the transfers in isolation.

Impact

Finally, Darktrace began to observe a large amount of suspicious SMB activity on the affected devices, most of which was SMB file encryption. DETECT observed the file extension ‘uw9nmvw’ being appended to many files across various internal shares and devices. In addition to this, a potential ransom note, ‘RECOVER-uw9nmvw-FILES.txt’, was detected on the network shortly after the start of the attack.

Figure 4: Depiction of the high-volume of suspicious SMB activity, including file encryption.


Conclusion

Ultimately, this incident show cases how Darktrace was able to successfully identify an emerging ransomware attack using its unrivalled anomaly-based detection capabilities, without having to rely on any previously established threat intelligence. Not only was Darktrace DETECT able to identify the ransomware at multiple stages of the kill chain, but it was also able to uncover the anomalous activity that took place in the buildup to the attack itself.

As the attack progressed along the cyber kill chain, escalating in severity at every juncture, DETECT was able to provide full visibility over the events. Through the successful identification of compromised devices, anomalous administrative credentials usage and encrypted files, Darktrace was able to greatly assist the customer, ensuring they were well-equipped to contain the incident and begin their incident management process.

Darktrace would have been able to aid the customer even further had they enabled its autonomous response technology on their network. Darktrace RESPOND would have taken targeted, mitigative action as soon as suspicious activity was detected, preventing the malicious actors from achieving their goals.

Credit to: Natalia Sánchez Rocafort, Cyber Security Analyst, Patrick Anjos, Senior Cyber Analyst.

MITRE Tactics/Techniques Mapping

RECONNAISSANCE

Scanning IP Blocks  (T1595.001)

RECONNAISSANCE

Vulnerability Scanning  (T1595.002)

IMPACT

Service Stop  (T1489)

LATERAL MOVEMENT

Taint Shared Content (T1080)

IMPACT

Data Encrypted for Impact (T1486)

INITIAL ACCESS

Replication Through Removable Media (T1200)

DEFENSE EVASION

Rogue Domain Controller (T1207)

COMMAND AND CONTROL

Domain Generation Algorithms (T1568.002)

EXECUTION

Windows Management Instrumentation (T1047)

INITIAL ACCESS

Phishing (T1190)

EXFILTRATION

Exfiltration Over C2 Channel (T1041)

IoC Table

IoC ----------- TYPE ------------- DESCRIPTION + PROBABILITY

CVD --------- credentials -------- Possible compromised credential

.UW9NMVW - File extension ----- Possible appended file extension

RECOVER-UW9NMVW-FILES.TXT - Ransom note - Possible ransom note observed

84.32.188[.]186 - IP address ------ C2 Endpoint

AS.EXECSVCT[.]COM - Hostname - C2 Endpoint

ZX.EXECSVCT[.]COM - Hostname - C2 Endpoint

QW.EXECSVCT[.]COM - Hostname - C2 Endpoint

EXECSVCT[.]COM - Hostname ------ C2 Endpoint

15.197.130[.]221 --- IP address ------ C2 Endpoint

AS59642 UAB CHERRY SERVERS - ASN - Possible ASN associated with C2 Endpoints

108.156.28[.]43

108.156.28[.]22

52.84.93[.]26

52.217.131[.]241

54.231.193[.]89 - IP addresses - Possible IP addresses associated with data exfiltration

103.203.59[.]3 -IP address ---- Possible IP address associated with initial attack vector

References:

[1] https://blog.netwrix.com/2021/11/30/what-is-dcsync-an-introduction/

[2] https://www.easeus.com/computer-instruction/delete-system32.html#:~:text=System32%20is%20a%20folder%20on,DLL%20files%2C%20and%20EXE%20files.

[3] https://www.techtarget.com/searchwindowsserver/definition/Windows-Management-Instrumentation#:~:text=WMI%20provides%20users%20with%20information,operational%20environments%2C%20including%20remote%20systems.

[4] https://www.virustotal.com/gui/ip-address/103.203.59[.]3

[5] https://otx.alienvault.com/indicator/ip/15.197.130[.]221

Inside the SOC
Darktrace cyber analysts are world-class experts in threat intelligence, threat hunting and incident response, and provide 24/7 SOC support to thousands of Darktrace customers around the globe. Inside the SOC is exclusively authored by these experts, providing analysis of cyber incidents and threat trends, based on real-world experience in the field.
Written by
Natalia Sánchez Rocafort
Cyber Security Analyst

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September 5, 2025

Cyber Assessment Framework v4.0 Raises the Bar: 6 Questions every security team should ask about their security posture

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What is the Cyber Assessment Framework?

The Cyber Assessment Framework (CAF) acts as guide for organizations, specifically across essential services, critical national infrastructure and regulated sectors, across the UK for assessing, managing and improving their cybersecurity, cyber resilience and cyber risk profile.

The guidance in the Cyber Assessment Framework aligns with regulations such as The Network and Information Systems Regulations (NIS), The Network and Information Security Directive (NIS2) and the Cyber Security and Resilience Bill.

What’s new with the Cyber Assessment Framework 4.0?

On 6 August 2025, the UK’s National Cyber Security Centre (NCSC) released Cyber Assessment Framework 4.0 (CAF v4.0) a pivotal update that reflects the increasingly complex threat landscape and the regulatory need for organisations to respond in smarter, more adaptive ways.

The Cyber Assessment Framework v4.0 introduces significant shifts in expectations, including, but not limited to:

  • Understanding threats in terms of the capabilities, methods and techniques of threat actors and the importance of maintaining a proactive security posture (A2.b)
  • The use of secure software development principles and practices (A4.b)
  • Ensuring threat intelligence is understood and utilised - with a focus on anomaly-based detection (C1.f)
  • Performance of proactive threat hunting with automation where appropriate (C2.a)

This blog post will focus on these components of the framework. However, we encourage readers to get the full scope of the framework by visiting the NCSC website where they can access the full framework here.

In summary, the changes to the framework send a clear signal: the UK’s technical authority now expects organisations to move beyond static rule-based systems and embrace more dynamic, automated defences. For those responsible for securing critical national infrastructure and essential services, these updates are not simply technical preferences, but operational mandates.

At Darktrace, this evolution comes as no surprise. In fact, it reflects the approach we've championed since our inception.

Why Darktrace? Leading the way since 2013

Darktrace was built on the principle that detecting cyber threats in real time requires more than signatures, thresholds, or retrospective analysis. Instead, we pioneered a self-learning approach powered by artificial intelligence, that understands the unique “normal” for every environment and uses this baseline to spot subtle deviations indicative of emerging threats.

From the beginning, Darktrace has understood that rules and lists will never keep pace with adversaries. That’s why we’ve spent over a decade developing AI that doesn't just alert, it learns, reasons, explains, and acts.

With Cyber Assessment Framework v4.0, the bar has been raised to meet this new reality. For technical practitioners tasked with evaluating their organisation’s readiness, there are five essential questions that should guide the selection or validation of anomaly detection capabilities.

6 Questions you should ask about your security posture to align with CAF v4

1. Can your tools detect threats by identifying anomalies?

Cyber Assessment Framework v4.0 principle C1.f has been added in this version and requires that, “Threats to the operation of network and information systems, and corresponding user and system behaviour, are sufficiently understood. These are used to detect cyber security incidents.”

This marks a significant shift from traditional signature-based approaches, which rely on known Indicators of Compromise (IOCs) or predefined rules to an expectation that normal user and system behaviour is understood to an extent enabling abnormality detection.

Why this shift?

An overemphasis on threat intelligence alone leaves defenders exposed to novel threats or new variations of existing threats. By including reference to “understanding user and system behaviour” the framework is broadening the methods of threat detection beyond the use of threat intelligence and historical attack data.

While CAF v4.0 places emphasis on understanding normal user and system behaviour and using that understanding to detect abnormalities and as a result, adverse activity. There is a further expectation that threats are understood in terms of industry specific issues and that monitoring is continually updated  

Darktrace uses an anomaly-based approach to threat detection which involves establishing a dynamic baseline of “normal” for your environment, then flagging deviations from that baseline — even when there’s no known IoCs to match against. This allows security teams to surface previously unseen tactics, techniques, and procedures in real time, whether it’s:

  • An unexpected outbound connection pattern (e.g., DNS tunnelling);
  • A first-time API call between critical services;
  • Unusual calls between services; or  
  • Sensitive data moving outside normal channels or timeframes.

The requirement that organisations must be equipped to monitor their environment, create an understanding of normal and detect anomalous behaviour aligns closely with Darktrace’s capabilities.

2. Is threat hunting structured, repeatable, and improving over time?

CAF v4.0 introduces a new focus on structured threat hunting to detect adverse activity that may evade standard security controls or when such controls are not deployable.  

Principle C2.a outlines the need for documented, repeatable threat hunting processes and stresses the importance of recording and reviewing hunts to improve future effectiveness. This inclusion acknowledges that reactive threat hunting is not sufficient. Instead, the framework calls for:

  • Pre-determined and documented methods to ensure threat hunts can be deployed at the requisite frequency;
  • Threat hunts to be converted  into automated detection and alerting, where appropriate;  
  • Maintenance of threat hunt  records and post-hunt analysis to drive improvements in the process and overall security posture;
  • Regular review of the threat hunting process to align with updated risks;
  • Leveraging automation for improvement, where appropriate;
  • Focus on threat tactics, techniques and procedures, rather than one-off indicators of compromise.

Traditionally, playbook creation has been a manual process — static, slow to amend, and limited by human foresight. Even automated SOAR playbooks tend to be stock templates that can’t cover the full spectrum of threats or reflect the specific context of your organisation.

CAF v4.0 sets the expectation that organisations should maintain documented, structured approaches to incident response. But Darktrace / Incident Readiness & Recovery goes further. Its AI-generated playbooks are bespoke to your environment and updated dynamically in real time as incidents unfold. This continuous refresh of “New Events” means responders always have the latest view of what’s happening, along with an updated understanding of the AI's interpretation based on real-time contextual awareness, and recommended next steps tailored to the current stage of the attack.

The result is far beyond checkbox compliance: a living, adaptive response capability that reduces investigation time, speeds containment, and ensures actions are always proportionate to the evolving threat.

3. Do you have a proactive security posture?

Cyber Assessment Framework v4.0 does not want organisations to detect threats, it expects them to anticipate and reduce cyber risk before an incident ever occurs. That is s why principle A2.b calls for a security posture that moves from reactive detection to predictive, preventative action.

A proactive security posture focuses on reducing the ease of the most likely attack paths in advance and reducing the number of opportunities an adversary has to succeed in an attack.

To meet this requirement, organisations could benefit in looking for solutions that can:

  • Continuously map the assets and users most critical to operations;
  • Identify vulnerabilities and misconfigurations in real time;
  • Model likely adversary behaviours and attack paths using frameworks like MITRE ATT&CK; and  
  • Prioritise remediation actions that will have the highest impact on reducing overall risk.

When done well, this approach creates a real-time picture of your security posture, one that reflects the dynamic nature and ongoing evolution of both your internal environment and the evolving external threat landscape. This enables security teams to focus their time in other areas such as  validating resilience through exercises such as red teaming or forecasting.

4. Can your team/tools customize detection rules and enable autonomous responses?

CAF v4.0 places greater emphasis on reducing false positives and acting decisively when genuine threats are detected.  

The framework highlights the need for customisable detection rules and, where appropriate, autonomous response actions that can contain threats before they escalate:

The following new requirements are included:  

  • C1.c.: Alerts and detection rules should be adjustable to reduce false positives and optimise responses. Custom tooling and rules are used in conjunction with off the shelf tooling and rules;
  • C1.d: You investigate and triage alerts from all security tools and take action – allowing for improvement and prioritization of activities;
  • C1.e: Monitoring and detection personnel have sufficient understanding of operational context and deal with workload effectively as well as identifying areas for improvement (alert or triage fatigue is not present);
  • C2.a: Threat hunts should be turned into automated detections and alerting where appropriate and automation should be leveraged to improve threat hunting.

Tailored detection rules improve accuracy, while automation accelerates response, both of which help satisfy regulatory expectations. Cyber AI Analyst allows for AI investigation of alerts and can dramatically reduce the time a security team spends on alerts, reducing alert fatigue, allowing more time for strategic initiatives and identifying improvements.

5. Is your software secure and supported?  

CAF v4.0 introduced a new principle which requires software suppliers to leverage an established secure software development framework. Software suppliers must be able to demonstrate:  

  • A thorough understanding of the composition and provenance of software provided;  
  • That the software development lifecycle is informed by a detailed and up to date understanding of threat; and  
  • They can attest to the authenticity and integrity of the software, including updates and patches.  

Darktrace is committed to secure software development and all Darktrace products and internally developed systems are developed with secure engineering principles and security by design methodologies in place. Darktrace commits to the inclusion of security requirements at all stages of the software development lifecycle. Darktrace is ISO 27001, ISO 27018 and ISO 42001 Certified – demonstrating an ongoing commitment to information security, data privacy and artificial intelligence management and compliance, throughout the organisation.  

6. Is your incident response plan built on a true understanding of your environment and does it adapt to changes over time?

CAF v4.0 raises the bar for incident response by making it clear that a plan is only as strong as the context behind it. Your response plan must be shaped by a detailed, up-to-date understanding of your organisation’s specific network, systems, and operational priorities.

The framework’s updates emphasise that:

  • Plans must explicitly cover the network and information systems that underpin your essential functions because every environment has different dependencies, choke points, and critical assets.
  • They must be readily accessible even when IT systems are disrupted ensuring critical steps and contact paths aren’t lost during an incident.
  • They should be reviewed regularly to keep pace with evolving risks, infrastructure changes, and lessons learned from testing.

From government expectation to strategic advantage

Cyber Assessment Framework v4.0 signals a powerful shift in cybersecurity best practice. The newest version sets a higher standard for detection performance, risk management, threat hunting software development and proactive security posture.

For Darktrace, this is validation of the approach we have taken since the beginning: to go beyond rules and signatures to deliver proactive cyber resilience in real-time.

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Disclaimer:

This document has been prepared on behalf of Darktrace Holdings Limited. It is provided for information purposes only to provide prospective readers with general information about the Cyber Assessment Framework (CAF) in a cyber security context. It does not constitute legal, regulatory, financial or any other kind of professional advice and it has not been prepared with the reader and/or its specific organisation’s requirements in mind. Darktrace offers no warranties, guarantees, undertakings or other assurances (whether express or implied)  that: (i) this document or its content are  accurate or complete; (ii) the steps outlined herein will guarantee compliance with CAF; (iii) any purchase of Darktrace’s products or services will guarantee compliance with CAF; (iv) the steps outlined herein are appropriate for all customers. Neither the reader nor any third party is entitled to rely on the contents of this document when making/taking any decisions or actions to achieve compliance with CAF. To the fullest extent permitted by applicable law or regulation, Darktrace has no liability for any actions or decisions taken or not taken by the reader to implement any suggestions contained herein, or for any third party products, links or materials referenced. Nothing in this document negates the responsibility of the reader to seek independent legal or other advice should it wish to rely on any of the statements, suggestions, or content set out herein.  

The cybersecurity landscape evolves rapidly, and blog content may become outdated or superseded. We reserve the right to update, modify, or remove any content without notice.

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September 5, 2025

Rethinking Signature-Based Detection for Power Utility Cybersecurity

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Lessons learned from OT cyber attacks

Over the past decade, some of the most disruptive attacks on power utilities have shown the limits of signature-based detection and reshaped how defenders think about OT security. Each incident reinforced that signatures are too narrow and reactive to serve as the foundation of defense.

2015: BlackEnergy 3 in Ukraine

According to CISA, on December 23, 2015, Ukrainian power companies experienced unscheduled power outages affecting a large number of customers — public reports indicate that the BlackEnergy malware was discovered on the companies’ computer networks.

2016: Industroyer/CrashOverride

CISA describes CrashOverride malwareas an “extensible platform” reported to have been used against critical infrastructure in Ukraine in 2016. It was capable of targeting industrial control systems using protocols such as IEC‑101, IEC‑104, and IEC‑61850, and fundamentally abused legitimate control system functionality to deliver destructive effects. CISA emphasizes that “traditional methods of detection may not be sufficient to detect infections prior to the malware execution” and recommends behavioral analysis techniques to identify precursor activity to CrashOverride.

2017: TRITON Malware

The U.S. Department of the Treasury reports that the Triton malware, also known as TRISIS or HatMan, was “designed specifically to target and manipulate industrial safety systems” in a petrochemical facility in the Middle East. The malware was engineered to control Safety Instrumented System (SIS) controllers responsible for emergency shutdown procedures. During the attack, several SIS controllers entered a failed‑safe state, which prevented the malware from fully executing.

The broader lessons

These events revealed three enduring truths:

  • Signatures have diminishing returns: BlackEnergy showed that while signatures can eventually identify adapted IT malware, they arrive too late to prevent OT disruption.
  • Behavioral monitoring is essential: CrashOverride demonstrated that adversaries abuse legitimate industrial protocols, making behavioral and anomaly detection more effective than traditional signature methods.
  • Critical safety systems are now targets: TRITON revealed that attackers are willing to compromise safety instrumented systems, elevating risks from operational disruption to potential physical harm.

The natural progression for utilities is clear. Static, file-based defenses are too fragile for the realities of OT.  

These incidents showed that behavioral analytics and anomaly detection are far more effective at identifying suspicious activity across industrial systems, regardless of whether the malicious code has ever been seen before.

Strategic risks of overreliance on signatures

  • False sense of security: Believing signatures will block advanced threats can delay investment in more effective detection methods.
  • Resource drain: Constantly updating, tuning, and maintaining signature libraries consumes valuable staff resources without proportional benefit.
  • Adversary advantage: Nation-state and advanced actors understand the reactive nature of signature defenses and design attacks to circumvent them from the start.

Recommended Alternatives (with real-world OT examples)

 Alternative strategies for detecting cyber attacks in OT
Figure 1: Alternative strategies for detecting cyber attacks in OT

Behavioral and anomaly detection

Rather than relying on signatures, focusing on behavior enables detection of threats that have never been seen before—even trusted-looking devices.

Real-world insight:

In one OT setting, a vendor inadvertently left a Raspberry Pi on a customer’s ICS network. After deployment, Darktrace’s system flagged elastic anomalies in its HTTPS and DNS communication despite the absence of any known indicators of compromise. The alerting included sustained SSL increases, agent‑beacon activity, and DNS connections to unusual endpoints, revealing a possible supply‑chain or insider risk invisible to static tools.  

Darktrace’s AI-driven threat detection aligns with the zero-trust principle of assuming the risk of a breach. By leveraging AI that learns an organization’s specific patterns of life, Darktrace provides a tailored security approach ideal for organizations with complex supply chains.

Threat intelligence sharing & building toward zero-trust philosophy

Frameworks such as MITRE ATT&CK for ICS provide a common language to map activity against known adversary tactics, helping teams prioritize detections and response strategies. Similarly, information-sharing communities like E-ISAC and regional ISACs give utilities visibility into the latest tactics, techniques, and procedures (TTPs) observed across the sector. This level of intel can help shift the focus away from chasing individual signatures and toward building resilience against how adversaries actually operate.

Real-world insight:

Darktrace’s AI embodies zero‑trust by assuming breach potential and continually evaluating all device behavior, even those deemed trusted. This approach allowed the detection of an anomalous SharePoint phishing attempt coming from a trusted supplier, intercepted by spotting subtle patterns rather than predefined rules. If a cloud account is compromised, unauthorized access to sensitive information could lead to extortion and lateral movement into mission-critical systems for more damaging attacks on critical-national infrastructure.

This reinforces the need to monitor behavioral deviations across the supply chain, not just known bad artifacts.

Defense-in-Depth with OT context & unified visibility

OT environments demand visibility that spans IT, OT, and IoT layers, supported by risk-based prioritization.

Real-world insight:

Darktrace / OT offers unified AI‑led investigations that break down silos between IT and OT. Smaller teams can see unusual outbound traffic or beaconing from unknown OT devices, swiftly investigate across domains, and get clear visibility into device behavior, even when they lack specialized OT security expertise.  

Moreover, by integrating contextual risk scoring, considering real-world exploitability, device criticality, firewall misconfiguration, and legacy hardware exposure, utilities can focus on the vulnerabilities that genuinely threaten uptime and safety, rather than being overwhelmed by CVE noise.  

Regulatory alignment and positive direction

Industry regulations are beginning to reflect this evolution in strategy. NERC CIP-015 requires internal network monitoring that detects anomalies, and the standard references anomalies 15 times. In contrast, signature-based detection is not mentioned once.

This regulatory direction shows that compliance bodies understand the limitations of static defenses and are encouraging utilities to invest in anomaly-based monitoring and analytics. Utilities that adopt these approaches will not only be strengthening their resilience but also positioning themselves for regulatory compliance and operational success.

Conclusion

Signature-based detection retains utility for common IT malware, but it cannot serve as the backbone of security for power utilities. History has shown that major OT attacks are rarely stopped by signatures, since each campaign targets specific systems with customized tools. The most dangerous adversaries, from insiders to nation-states, actively design their operations to avoid detection by signature-based tools.

A more effective strategy prioritizes behavioral analytics, anomaly detection, and community-driven intelligence sharing. These approaches not only catch known threats, but also uncover the subtle anomalies and novel attack techniques that characterize tomorrow’s incidents.

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Daniel Simonds
Director of Operational Technology
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