Note: In order to name anonymity, real organization names have been replaced, all names used in this blog are fictitious.

What are critical national infrastructure sectors?

Critical National Infrastructure (CNI) sectors encompass of assets, systems, and networks essential to the functioning of society. Any disruption or destruction of these sectors could have wide-reaching and potentially disastrous effects on a country’s economy, security and/or healthcare services [1].

Cyber risks across Transportation Systems sector

Transportation Systems is one such CNI sector comprising of interconnected networks of fixed and mobile assets managed by both public and private operators. These systems are highly interdependent with other CNI sectors too. As such, the digital technologies this sector relies on – such as positioning and tracking, signaling, communications, industrial system controls, and data and business management – are often interconnected through different networks and remote access terminals. This interconnectedness creates multiple entry points that need to be security across the supply.

Digital transformation has swept through CNI sectors in recent years, including Transportation Systems. These organizations are now increasingly dependent on third-party and cloud providers for data storage and transmission, making their supply chains vulnerable to exploitation by malicious actors [2].

The exploitation of legitimate and popular cloud services mirrors the well-known “living-off-the-land” techniques, which are not being adapted to the cloud along with the resources they support. In one recent case previously discussed by Darktrace, for example, a phishing attack attempted to abuse Dropbox to deliver malicious payloads.

Zero-Trust within CNI Sectors

One recommended approach to secure an organization’s supply chain and cloud environments is the implementation of zero-trust strategies, which remove inherent trust within the network [3] [4]. The principle of “never trust, always verify” is widely recognized as an architectural design, with 63% of organizations surveyed by Gartner reportedly implementing a zero-trust strategy, but in most cases to less than 50% of their environments [5]

Although this figure reflects the reality and challenge of balancing operations and security, demands from the threat landscape and supply chain risks mean that organizations must adopt zero-trust principles in areas not traditionally considered part of network architecture, such as email and cloud environments.

Email is often the primary entry point for cyber-attacks with Business Email Compromise (BEC) being a major threat to CNI organizations. However, the application of zero-trust principles to secure email environments is still not well understood. Common misconceptions include:

• “Positively identifying known and trusted senders” – Maintaining a list of “known and trusted senders” contradicts the zero-trust model, which assumes that no entity is inherently trustworthy.
• “Using DMARC, DKIM and SPF” – While these protocols offer some protection, they are often insufficient on their own, as they can be bypassed and do not protect against email account takeovers. Research published from Darktrace’s last two threat reports consistently shows that at least 60% of phishing emails detected by Darktrace had bypassed Domain-based Message Authentication, Reporting & Conformance (DMARC) [6] [7].  
• “Mapping transaction flows between internal and external users to determine what access is required/not required” – Although this aligns with the principles of least privilege, it is too static for today’s dynamic supply chains and evolving digital infrastructure. This approach also suggests the existence of “trusted” access routes into a network.

Attack Overview

In July 2024, Darktrace / EMAIL™ detected and contained a sophisticated phishing attack leveraging Microsoft SharePoint. This attack exploited the trusted relationship between a Darktrace customer in the public transport sector and a compromised supplier. Traditional methods, such as those detailed above, would likely have failed to defend against such an advanced threat. However, Darktrace’s behavioral analysis and zero-trust approach to email security allowed it to successfully identify and neutralize the attack, preventing any potential disruption.

Initial Intrusion Attempt

The observed phishing attack by Darktrace would suggest that the customer’s supplier was targeted by a similar campaign beforehand. This initial breach likely allowed the attacker to use the now compromised account as a vector to compromise additional accounts and networks.

On July 9, Darktrace / EMAIL identified a significant spike in inbound emails from “supplier@engineeringcompany[.]com”. The emails appeared to be legitimate notifications sent via SharePoint and contained a file named “Payment Applications Docs”.

This reflects a common technique in malicious social engineering attempts, where references to payment are used to draw attention and prompt a response. Darktrace observed a large number of recipients within the organization receiving the same file, suggesting that the motive was likely credential harvesting rather than financial gain. Financially motivated attacks typically require a more targeted, ‘under-the-radar’ approach to be successful.

These phishing emails were able to bypass the customer’s email gateways as they were sent from a trusted and authoritative source, SharePoint, and utilized an email address with which the customer had previously corresponded. The compromised account was likely whitelisted by traditional email security tools that rely on SPF, DKIM, and DMAC, allowing the malicious emails to evade detection.

Autonomous Response

However, Darktrace / EMAIL did not use these static rules to automatically trust the email. Darktrace’s Self-Learning AI detected the following anomalies:

• Although the sender was known, it was not normal for the supplier to share files with the customer via SharePoint.
• The supplier initiated an unusually large number of file shares in a short period of time, indicating potential spam activity.
• The SharePoint link had wide access permissions, which is unusual for a sensitive payment document legitimately shared between established contacts.

Darktrace understood that the email activity constituted a significant deviation in expected behavior between the sender and customer, regardless of the known sender and use of a legitimate filesharing platform like SharePoint.

As a result, Darktrace took action to hold more than 100 malicious emails connected to the phishing attack, preventing them from landing in recipient inboxes in the first instance.  By taking a behavioral approach to securing customer email environments, Darktrace’s Self-Learning AI embodies the principles of zero trust, assessing each interaction in real-time against a user’s dynamic baseline rather than relying on static and often inaccurate rules to define trust.

Conclusion

Cloud services, such as SharePoint, offer significant advantages to the transportation sector by streamlining data exchange with supply chain partners and facilitating access to information for analytics and planning. However, these benefits come with notable risks. 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 CNI. Even a brief disruption in cloud access can have severe economic repercussions due to the sector’s dependence on these services for resource coordination and the cascading impacts on other critical systems [9].

While supply chain resilience is often evaluated based on a supplier’s initial compliance with baseline standards, organizations must be wary of potential future threats and focus on post-implementation security. It is essential for organizations to employ strategies to protect their assets from attacks that would exploit vulnerabilities within the trusted supply chain. Given that CNI and the transportation sector are prime targets for state-sponsored actors and Advanced Persistent Threat (APT) groups, the complex and interconnected nature of their supply chains opens the door for opportunistic attackers.

Defenders face the challenge of ensuring secure access and collaboration across numerous, dynamic assets, often without full visibility. Therefore, security solutions must be as dynamic as the threats they face, avoiding reliance on static rules. Real-time assessment of devices behavior, even if deemed trusted by end-users and human security teams, is crucial for maintaining security.

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.

Credit to Nicole Wong, Senior Cyber Analyst Consultant and Ryan Traill, Threat Content Lead

Appendices

Darktrace Model Detections

Key model alerts:

• Personalized Sharepoint Share + New Unknown Link
• Personalized Sharepoint Share + Bad Display Text
• Personalized Sharepoint Share + Distant Recipient Interaction with Domain
• Personalized Sharepoint Share + Sender Surge
• Personalized Sharepoint Share + Wide Access Sharepoint Link

MITRE ATT&CK Mapping

Resource Development • Compromise Accounts: Cloud Accounts • T1586.003

Initial Access • Supply Chain Compromise • T1195

References

[1] https://www.cisa.gov/topics/critical-infrastructure-security-and-resilience/critical-infrastructure-sectors

[2]  https://committees.parliament.uk/writtenevidence/126313/pdf/

[3] https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-161r1.pdf

[4] https://cloudsecurityalliance.org/press-releases/2023/11/15/cloud-security-alliance-launches-the-industry-s-first-authoritative-zero-trust-training-and-credential-the-certificate-of-competence-in-zero-trust-cczt

[5] https://www.gartner.com/en/documents/5286863#:~:text=Summary,anticipate%20staffing%20and%20cost%20increases.

[6] https://darktrace.com/threat-report-2023

[7] https://darktrace.com/resources/first-6-half-year-threat-report-2024

[8] https://dfrlab.org/2023/07/10/critical-infrastructure-and-the-cloud-policy-for-emerging-risk/#transportation

[9] https://access-national-risk-register.service.cabinetoffice.gov.uk/risk-scenario/cyber-attack-transport-sector

Introduction: Darktrace's Threat Research

Defenders must understand the threat landscape in order to protect against it. We can do that with threat intelligence.

At Darktrace, we approach threat intelligence with a unique perspective. Unlike traditional security vendors that rely on established patterns from past incidents, our strategy is rooted in the belief that identifying behavioral anomalies is crucial for identifying both known and novel threats.

For our analysts and researchers, the incidents detected by our AI mark the beginning of a deeper investigation, aiming to connect mitigated threats to wider trends from across the threat landscape. Through hindsight analysis, we have highlighted numerous threats, including zero day, N day, and other novel attacks, showcasing their evolving nature and Darktrace’s ability to identify them.  

For the first half of 2024, we’ve observed major trends around subscription-based attack models, advanced TTPs, and sophisticated email attacks. Read on to discover some of our key insights into the current cybersecurity threat landscape.  

Malware-as-a-Service continues to pose significant risk for organizations

Many of the prevalent threats observed by Darktrace heavily utilized Malware-as-a-Service (MaaS) tools. This is likely because of the lucrative subscription-based income of MaaS ecosystems as well as the low barrier to entry and high demand. By offering pre-packed, plug-and-play malware, the MaaS market has enabled even inexperienced attackers to carry out potentially disruptive attacks, regardless of their level of skill or technical ability.  

When comparing the latest observed threats with the previous half year’s data, there are several returning threats, notably Mirai, AsyncRAT, Emotet, and NjRAT.  

This highlights that while MaaS strains often adapt their TTPs from one campaign to the next, many strains remain unchanged yet continue to achieve success. This suggests that some security teams and organizations are still falling short in defending their environments.

The persistence of known malware strains and information stealers particularly affects smaller organizations that are likely under-resourced and outsource portions of their security responsibilities. Additionally, larger organizations with poor cyber hygiene or extensive guest subnets may also be at risk.

The Darktrace experts anticipate that MaaS will remain a prevalent part of the threat landscape for the foreseeable future.

Double extortion methods are now prevalent amongst ransomware strains

As ransomware continues to be a top security concern for organizations, Darktrace’s Threat Research team has identified three predominant ransomware strains impacting customers: Akira, Lockbit, and Black Basta.  

While these ransomware families are not new, they have remained vigilant threats in recent years, indicating that these variants are continuing to evolve and adopt new, sophisticated tactics to circumvent security measures. As organizations harden their digital defenses by understanding and pre-empting the TTPs of known ransomware strains, threat actors often incorporate new strategies making them more sophisticated, faster, and harder to defend against.  

One such strategy noted by Darktrace is the adoption of double extortion methods. Malicious actors will not only encrypt their target’s data, but also exfiltrate sensitive files with threat of publication if the ransom is not paid.  

In the case of Akira in particular, Darktrace observed attackers attempting to exfiltrate data within 12 hours of the initial file encryption, all but confirming that double extortion is a standard part of their playbook.

Email phishing shows no signs of slowing down

With a majority of attacks originating from email, it is crucial that organizations secure the inbox and beyond.  

Between December 21, 2023, and July 5, 2024, Darktrace / EMAIL detected 17.8 million phishing emails across the fleet, with 62% of these phishing emails successfully bypassing Domain-based Message Authentication, Reporting, and Conformance (DMARC) verification checks.

These are not the only types of email attacks we observed. Darktrace detected 550,000 malicious QR codes that, when scanned, would direct recipients to a malicious endpoint where attackers can infect a device with malware or steal a user’s login credentials.  

While most traditional email security measures are not able to scan for QR codes, Darktrace / EMAIL is not only able to detect them but also identify their destination, blocking any emails found to lead to suspicious endpoints.

Conclusion

The threat landscape continues to evolve, but new threats often build upon old foundations rather than replacing them. While we have observed the emergence of new malware families, many attacks are carried out by the usual suspects that we have seen over the last few years, still utilizing familiar techniques and malware variants. This indicates that cyber threats persist due to the abundance of exploitable vulnerabilities.

In the realm of email security, familiar attacks are also changing, with more impersonations of trusted companies and multistage payload attacks. These email campaigns target select organizations, or even individuals, more efficiently than traditional mass phishing attacks.  

As attacks appear with greater frequency and sophistication, defenders must have timely detection and containment capabilities to handle all emerging threats. Read the complete 2024 Half-Year Threat Report to discover all the latest threat landscape trends and the Darktrace Threat Research team’s recommendations.  

Download the full report here.