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September 4, 2024

What you need to know about FAA Security Protection Regulations 2024

This blog gives an overview of the proposed FAA regulations for safeguarding aviation systems and their cyber-physical networks. Read more to discover key points, challenges, and potential solutions for each use case.
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
Daniel Simonds
Director of Operational Technology
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04
Sep 2024

Overview of FAA Rules 2024

Objective

The goal of the Federal Aviation Administration amended rules is to create new design standards that protect airplane systems from intentional unauthorized electronic interactions (IUEI), which can pose safety risks. The timely motivation for this goal is due to the ongoing trend in aircraft design, which features a growing integration of airplane, engine, and propeller systems, along with expanded connectivity to both internal and external data networks and services.

“This proposed rulemaking would impose new design standards to address cybersecurity threats for transport category airplanes, engines, and propellers. The intended effect of this proposed action is to standardize the FAA’s criteria for addressing cybersecurity threats, reducing certification costs and time while maintaining the same level of safety provided by current special conditions.” (1)

Background

Increasing integration of aircraft systems with internal and external networks raises cybersecurity vulnerability concerns.

Key vulnerabilities include:  

  • Field Loadable Software
  • Maintenance laptops
  • Public networks (e.g., Internet)
  • Wireless sensors
  • USB devices
  • Satellite communications
  • Portable devices and flight bags  

Requirements for Applicants

Applicants seeking design approval must:

  • Provide isolation or protection from unauthorized access
  • Prevent inadvertent or malicious changes to aircraft systems
  • Establish procedures to maintain cybersecurity protections

Purpose

“These changes would introduce type certification and continued airworthiness requirements to protect the equipment, systems, and networks of transport category airplanes, engines, and propellers against intentional unauthorized electronic interactions (IUEI)1 that could create safety hazards. Design approval applicants would be required to identify, assess, and mitigate such hazards, and develop Instructions for Continued Airworthiness (ICA) that would ensure such protections continue in service.” (1)

Key points:

  • Introduce new design standards to address cybersecurity threats for transport category airplanes, engines, and propellers.
  • Aim to reduce certification costs and time while maintaining safety levels similar to current special conditions

Applicant Responsibilities for Identifying, Assessing, and Mitigating IUEI Risks

The proposed rule requires applicants to safeguard airplanes, engines, and propellers from intentional unauthorized electronic interactions (IUEI). To do this, they must:

  1. Identify and assess risks: Find and evaluate any potential electronic threats that could harm safety.
  2. Mitigate risks: Take steps to prevent these threats from causing problems, ensuring the aircraft remain safe and functional.

Let’s break down each of the requirements:

Performing risk analysis

“For such identification and assessment of security risk, the applicant would be required to perform a security risk analysis to identify all threat conditions associated with the system, architecture, and external or internal interfaces.”(3)

Challenge

The complexity and variety of OT devices make it difficult and time-consuming to identify and associate CVEs with assets. Security teams face several challenges:

  • Prioritization Issues: Sifting through extensive CVE lists to prioritize efforts is a struggle.
  • Patch Complications: Finding corresponding patches is complicated by manufacturer delays and design flaws.
  • Operational Constraints: Limited maintenance windows and the need for continuous operations make it hard to address vulnerabilities, often leaving them unresolved for years.
  • Inadequate Assessments: Standard CVE assessments may not fully capture the risks associated with increased connectivity, underscoring the need for a contextualized risk assessment approach.

This highlights the need for a more effective and tailored approach to managing vulnerabilities in OT environments.

Assessing severity of risks

“The FAA would expect such risk analysis to assess the severity of the effect of threat conditions on associated assets (system, architecture, etc.), consistent with the means of compliance the applicant has been using to meet the FAA’s special conditions on this topic.” (3)

Challenge

As shown by the MITRE ATT&CK® Techniques for ICS matrices, threat actors can exploit many avenues beyond just CVEs. To effectively defend against these threats, security teams need a broader perspective, considering lateral movement and multi-stage attacks.

Challenges in Vulnerability Management (VM) cycles include:

  • Initiation: VM cycles often start with email updates from the Cybersecurity and Infrastructure Security Agency (CISA), listing new CVEs from the NIST database.
  • Communication: Security practitioners must survey and forward CVE lists to networking teams at facilities that might be running the affected assets. Responses from these teams are inconsistent, leading vulnerability managers to push patches that may not fit within limited maintenance windows.
  • Asset Tracking: At many OT locations, determining if a company is running a specific firmware version can be extremely time-consuming. Teams often rely on spreadsheets and must perform manual checks by physically visiting production floors ("sneaker-netting").
  • Coordination: Plant engineers and centralized security teams must exchange information to validate asset details and manually score vulnerabilities, further complicating and delaying remediation efforts.

Determine likelihood of exploitation

“Such assessment would also need to analyze these vulnerabilities for the likelihood of exploitation.” (3)

Challenge

Even when a vulnerability is identified, its actual impact can vary significantly based on the specific configurations, processes, and technologies in use within the organization. This creates challenges for OT security practitioners:

  • Risk Assessment: Accurately assessing and prioritizing the risk becomes difficult without a clear understanding of how the vulnerability affects their unique systems.
  • Decision-Making: Practitioners may struggle to determine whether immediate action is necessary, balancing the risk of operational downtime against the need for security.
  • Potential Consequences: This uncertainty can lead to either leaving critical systems exposed or causing unnecessary disruptions by applying measures that aren't truly needed.

This complexity underscores the challenge of making informed, timely decisions in OT security environments.

Vulnerability mitigation

“The proposed regulation would then require each applicant to 'mitigate' the vulnerabilities, and the FAA expects such mitigation would occur through the applicant’s installation of single or multilayered protection mechanisms or process controls to ensure functional integrity, i.e., protection.” (3)

Challenge

OT security practitioners face a constant challenge in balancing security needs with the requirement to maintain operational uptime. In many OT environments, especially in critical infrastructure, applying security patches can be risky:

  • Risk of Downtime: Patching can disrupt essential processes, leading to significant financial losses or even safety hazards.
  • Operational Continuity vs. Security: Practitioners often prioritize operational continuity, sometimes delaying timely security updates.
  • Alternative Strategies: To protect systems without direct patching, they must implement compensating controls, further complicating security efforts.

This delicate balance between security and uptime adds complexity to the already challenging task of securing OT environments.

Establishing procedures/playbooks

“Finally, each applicant would be required to include the procedures within their instructions for continued airworthiness necessary to maintain such protections.” (3)

Challenge

SOC teams typically have a lag before their response, leading to a higher dwell time and bigger overall costs. On average, only 15% of the total cost of ransomware is affiliated with the ransom itself (2). The rest is cost from business interruption. This means it's crucial that organizations can respond and recover earlier. 

Darktrace / OT enabling compliance and enhanced cybersecurity

Darktrace's OT solution addresses the complex challenges of cybersecurity compliance in Operational Technology (OT) environments by offering a comprehensive approach to risk management and mitigation.

Key risk management features include:

  • Contextualized Risk Analysis: Darktrace goes beyond traditional vulnerability scoring, integrating IT, OT, and CVE data with MITRE techniques to map critical attack paths. This helps in identifying and prioritizing vulnerabilities based on their exposure, difficulty of exploitation, and network impact.
  • Guidance on Remediation: When patches are unavailable, Darktrace provides alternative strategies to bolster defenses around vulnerable assets, ensuring unpatched systems are not left exposed—a critical need in OT environments where operational continuity is essential.
  • AI-Driven Adaptability: Darktrace's AI continuously adapts to your organization as it grows; refining incident response playbooks bespoke to your environment in real-time. This ensures that security teams have the most up-to-date, tailored strategies, reducing response times and minimizing the impact of security incidents.

Ready to learn more?  

Darktrace / OT doesn’t just offer risk management capabilities. It is the only solution  
that leverages Self-Learning AI to understand your normal business operations, allowing you to detect and stop insider, known, unknown, and zero-day threats at scale.  

Dive deeper into how Darktrace / OT secures critical infrastructure organizations with in-depth insights on its advanced capabilities. Download the Darktrace / OT Solution Brief to explore the technology behind its AI-driven protection and see how it can transform your OT security strategy.

Curious about how Darktrace / OT enhances aviation security? Explore our customer story on Brisbane Airport to see how our solution is transforming security operations in the aviation sector.  

References

  1. https://research-information.bris.ac.uk/ws/portalfiles/portal/313646831/Catch_Me_if_You_Can.pdf
  1. https://www.bleepingcomputer.com/news/security/ransom-payment-is-roughly-15-percent-of-the-total-cost-of-ransomware-attacks/
  1. https://public-inspection.federalregister.gov/2024-17916.pdf?mod=djemCybersecruityPro&tpl=cs
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
Daniel Simonds
Director of Operational Technology

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November 28, 2025

From Amazon to Louis Vuitton: How Darktrace Detects Black Friday Phishing Attacks

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Why Black Friday Drives a Surge in Phishing Attacks

In recent years, Black Friday has shifted from a single day of online retail sales and discounts to an extended ‘Black Friday Week’, often preceded by weeks of online hype. During this period, consumers are inundated with promotional emails and marketing campaigns as legitimate retailers compete for attention.

Unsurprisingly, this surge in legitimate communications creates an ideal environment for threat actors to launch targeted phishing campaigns designed to mimic legitimate retail emails. These campaigns often employ social engineering techniques that exploit urgency, exclusivity, and consumer trust in well-known brands, tactics designed to entice recipients into opening emails and clicking on malicious links.

Additionally, given the seasonal nature of Black Friday and the ever-changing habits of consumers, attackers adopt new tactics and register fresh domains each year, rather than reusing domains previously flagged as spam or phishing endpoints. While this may pose a challenge for traditional email security tools, it presents no such difficulty for Darktrace / EMAIL and its anomaly-based approach.

In the days and weeks leading up to ‘Black Friday’, Darktrace observed a spike in sophisticated phishing campaigns targeting consumers, demonstrating how attackers combine phycological manipulation with technical evasion to bypass basic security checks during this high-traffic period. This blog showcases several notable examples of highly convincing phishing emails detected and contained by Darktrace / EMAIL in mid to late November 2025.

Darktrace’s Black Friday Detections

Brand Impersonation: Deal Watchdogs’ Amazon Deals

The impersonation major online retailers has become a common tactic in retail-focused attacks, none more so than Amazon, which ranked as the fourth most impersonated brand in 2024, only behind Microsoft, Apple, Google, and Facebook [1]. Darktrace’s own research found Amazon to be the most mimicked brand, making up 80% of phishing attacks in its analysis of global consumer brands.

When faced with an email that appears to come from a trusted sender like Amazon, recipients are far more likely to engage, increasing the success rate of these phishing campaigns.

In one case observed on November 16, Darktrace detected an email with the subject line “NOW LIVE: Amazon’s Best Early Black Friday Deals on Gadgets Under $60”. The email was sent to a customer by the sender ‘Deal Watchdogs’, in what appeared to be an attempt to masquerade as a legitimate discount-finding platform. No evidence indicated that the company was legitimate. In fact, the threat actor made no attempt to create a convincing name, and the domain appeared to be generated by a domain generation algorithm (DGA), as shown in Figure 2.

Although the email was sent by ‘Deal Watchdogs’, it attempted to impersonate Amazon by featuring realistic branding, including the Amazon logo and a shade of orange similar to that used by them for the ‘CLICK HERE’ button and headline text.

Figure 1: The contents of the email observed by Darktrace, featuring authentic-looking Amazon branding.

Darktrace identified that the email, marked as urgent by the sender, contained a suspicious link to a Google storage endpoint (storage.googleapis[.]com), which had been hidden by the text “CLICK HERE”. If clicked, the link could have led to a credential harvester or served as a delivery vector for a malicious payload hosted on the Google storage platform.

Fortunately, Darktrace immediately identified the suspicious nature of this email and held it before delivery, preventing recipients from ever receiving or interacting with the malicious content.

Figure 2: Darktrace / EMAIL’s detection of the malicious phishing email sent to a customer.

Around the same time, Darktrace detected a similar email attempting to spoof Amazon on another customer’s network with the subject line “Our 10 Favorite Deals on Amazon That Started Today”, also sent by ‘Deal Watchdogs,’ suggesting a broader campaign.

Analysis revealed that this email originated from the domain petplatz[.]com, a fake marketing domain previously linked to spam activity according to open-source intelligence (OSINT) [2].

Brand Impersonation: Louis Vuitton

A few days later, on November 20, Darktrace / EMAIL detected a phishing email attempting to impersonate the luxury fashion brand Louis Vuitton. At first glance, the email, sent under the name ‘Louis Vuitton’ and titled “[Black Friday 2025] Discover Your New Favorite Louis Vuitton Bag – Elegance Starts Here”, appeared to be a legitimate Black Friday promotion. However, Darktrace’s analysis uncovered several red flags indicating a elaborate brand impersonation attempt.

The email was not sent by Louis Vuitton but by rskkqxyu@bookaaatop[.]ru, a Russia-based domain never before observed on the customer’s network. Darktrace flagged this as suspicious, noting that .ru domains were highly unusual for this recipient’s environment, further reinforcing the likelihood of malicious intent. Subsequent analysis revealed that the domain had only recently registered and was flagged as malicious by multiple OSINT sources [3].

Figure 3: Darktrace / EMAIL’s detection of the malicious email attempting to spoofLouis Vuitton, originating from a suspicious Russia-based domain.

Darktrace further noted that the email contained a highly suspicious link hidden behind the text “View Collection” and “Unsubscribe,” ensuring that any interaction, whether visiting the supposed ‘handbag store’ or attempting to opt out of marketing emails, would direct recipients to the same endpoint. The link resolved to xn--80aaae9btead2a[.]xn--p1ai (топааабоок[.]рф), a domain confirmed as malicious by multiple OSINT sources [4]. At the time of analysis, the domain was inaccessible, likely due to takedown efforts or the short-lived nature of the campaign.

Darktrace / EMAIL blocked this email before it reached customer inboxes, preventing recipients from interacting with the malicious content and averting any disruption.

Figure 4: The suspicious domain linked in the Louis Vuitton phishing email, now defunct.

Too good to be true?

Aside from spoofing well-known brands, threat actors frequently lure consumers with “too good to be true” luxury offers, a trend Darktrace observed in multiple cases throughout November.

In one instance, Darktrace identified an email with the subject line “[Black Friday 2025] Luxury Watches Starting at $250.” Emails contained a malicious phishing link, hidden behind text like “Rolex Starting from $250”, “Shop Now”, and “Unsubscribe”.

Figure 5: Example of a phishing email detected by Darktrace, containing malicious links concealed behind seemingly innocuous text.

Similarly to the Louis Vuitton email campaign described above, this malicious link led to a .ru domain (hxxps://x.wwwtopsalebooks[.]ru/.../d65fg4er[.]html), which had been flagged as malicious by multiple sources [5].

Figure 6: Darktrace / EMAIL’s detection of a malicious email promoting a fake luxury watch store, which was successfully held from recipient inboxes.

If accessed, this domain would redirect users to luxy-rox[.]com, a recently created domain (15 days old at the time of writing) that has also been flagged as malicious by OSINT sources [6]. When visited, the redirect domain displayed a convincing storefront advertising high-end watches at heavily discounted prices.

Figure 7: The fake storefront presented upon visiting the redirectdomain, luxy-rox[.]com.

Although the true intent of this domain could not be confirmed, it was likely a scam site or a credential-harvesting operation, as users were required to create an account to complete a purchase. As of the time or writing, the domain in no longer accessible .

This email illustrates a layered evasion tactic: attackers employed multiple domains, rapid domain registration, and concealed redirects to bypass detection. By leveraging luxury branding and urgency-driven discounts, the campaign sought to exploit seasonal shopping behaviors and entice victims into clicking.

Staying Protected During Seasonal Retail Scams

The investigation into these Black Friday-themed phishing emails highlights a clear trend: attackers are exploiting seasonal shopping events with highly convincing campaigns. Common tactics observed include brand impersonation (Amazon, Louis Vuitton, luxury watch brands), urgency-driven subject lines, and hidden malicious links often hosted on newly registered domains or cloud services.

These campaigns frequently use redirect chains, short-lived infrastructure, and psychological hooks like exclusivity and luxury appeal to bypass user scepticism and security filters. Organizations should remain vigilant during retail-heavy periods, reinforcing user awareness training, link inspection practices, and anomaly-based detection to mitigate these evolving threats.

Credit to Ryan Traill (Analyst Content Lead) and Owen Finn (Cyber Analyst)

Appendices

References

1.        https://keepnetlabs.com/blog/top-5-most-spoofed-brands-in-2024

2.        https://www.virustotal.com/gui/domain/petplatz.com

3.        https://www.virustotal.com/gui/domain/bookaaatop.ru

4.        https://www.virustotal.com/gui/domain/xn--80aaae9btead2a.xn--p1ai

5.        https://www.virustotal.com/gui/url/e2b868a74531cd779d8f4a0e1e610ec7f4efae7c29d8b8ab32c7a6740d770897?nocache=1

6.        https://www.virustotal.com/gui/domain/luxy-rox.com

Indicators of Compromise (IoCs)

IoC – Type – Description + Confidence

petplatz[.]com – Hostname – Spam domain

bookaaatop[.]ru – Hostname – Malicious Domain

xn--80aaae9btead2a[.]xn--p1ai (топааабоок[.]рф) – Hostname - Malicious Domain

hxxps://x.wwwtopsalebooks[.]ru/.../d65fg4er[.]html) – URL – Malicious Domain

luxy-rox[.]com – Hostname -  Malicious Domain

MITRE ATT&CK Mapping  

Tactic – Technique – Sub-Technique  

Initial Access - Phishing – (T1566)  

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About the author
Ryan Traill
Analyst Content Lead

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November 27, 2025

CastleLoader & CastleRAT: Behind TAG150’s Modular Malware Delivery System

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What is TAG-150?

TAG-150, a relatively new Malware-as-a-Service (MaaS) operator, has been active since March 2025, demonstrating rapid development and an expansive, evolving infrastructure designed to support its malicious operations. The group employs two custom malware families, CastleLoader and CastleRAT, to compromise target systems, with a primary focus on the United States [1]. TAG-150’s infrastructure included numerous victim-facing components, such as IP addresses and domains functioning as command-and-control (C2) servers associated with malware families like SecTopRAT and WarmCookie, in addition to CastleLoader and CastleRAT [2].

As of May 2025, CastleLoader alone had infected a reported 469 devices, underscoring the scale and sophistication of TAG-150’s campaign [1].

What are CastleLoader and CastleRAT?

CastleLoader is a loader malware, primarily designed to download and install additional malware, enabling chain infections across compromised systems [3]. TAG-150 employs a technique known as ClickFix, which uses deceptive domains that mimic document verification systems or browser update notifications to trick victims into executing malicious scripts. Furthermore, CastleLoader leverages fake GitHub repositories that impersonate legitimate tools as a distribution method, luring unsuspecting users into downloading and installing malware on their devices [4].

CastleRAT, meanwhile, is a remote access trojan (RAT) that serves as one of the primary payloads delivered by CastleLoader. Once deployed, CastleRAT grants attackers extensive control over the compromised system, enabling capabilities such as keylogging, screen capturing, and remote shell access.

TAG-150 leverages CastleLoader as its initial delivery mechanism, with CastleRAT acting as the main payload. This two-stage attack strategy enhances the resilience and effectiveness of their operations by separating the initial infection vector from the final payload deployment.

How are they deployed?

Castleloader uses code-obfuscation methods such as dead-code insertion and packing to hinder both static and dynamic analysis. After the payload is unpacked, it connects to its command-and-control server to retrieve and running additional, targeted components.

Its modular architecture enables it to function both as a delivery mechanism and a staging utility, allowing threat actors to decouple the initial infection from payload deployment. CastleLoader typically delivers its payloads as Portable Executables (PEs) containing embedded shellcode. This shellcode activates the loader’s core module, which then connects to the C2 server to retrieve and execute the next-stage malware.[6]

Following this, attackers deploy the ClickFix technique, impersonating legitimate software distribution platforms like Google Meet or browser update notifications. These deceptive sites trick victims into copying and executing PowerShell commands, thereby initiating the infection kill chain. [1]

When a user clicks on a spoofed Cloudflare “Verification Stepprompt, a background request is sent to a PHP script on the distribution domain (e.g., /s.php?an=0). The server’s response is then automatically copied to the user’s clipboard using the ‘unsecuredCopyToClipboard()’ function. [7].

The Python-based variant of CastleRAT, known as “PyNightShade,” has been engineered with stealth in mind, showing minimal detection across antivirus platforms [2]. As illustrated in Figure 1, PyNightShade communicates with the geolocation API service ip-api[.]com, demonstrating both request and response behavior

Packet Capture (PCAP) of PyNightShade, the Python-based variant of CastleRAT, communicating with the geolocation API service ip-api[.]com.
Figure 1: Packet Capture (PCAP) of PyNightShade, the Python-based variant of CastleRAT, communicating with the geolocation API service ip-api[.]com.

Darktrace Coverage

In mid-2025, Darktrace observed a range of anomalous activities across its customer base that appeared linked to CastleLoader, including the example below from a US based organization.

The activity began on June 26, when a device on the customer’s network was observed connecting to the IP address 173.44.141[.]89, a previously unseen IP for this network along with the use of multiple user agents, which was also rare for the user.  It was later determined that the IP address was a known indicator of compromise (IoC) associated with TAG-150’s CastleRAT and CastleLoader operations [2][5].

Figure 2: Darktrace’s detection of a device making unusual connections to the malicious endpoint 173.44.141[.]89.

The device was observed downloading two scripts from this endpoint, namely ‘/service/download/data_5x.bin’ and ‘/service/download/data_6x.bin’, which have both been linked to CastleLoader infections by open-source intelligence (OSINT) [8]. The archives contains embedded shellcode, which enables attackers to execute arbitrary code directly in memory, bypassing disk writes and making detection by endpoint detection and response (EDR) tools significantly more difficult [2].

 Darktrace’s detection of two scripts from the malicious endpoint.
Figure 3: Darktrace’s detection of two scripts from the malicious endpoint.

In addition to this, the affected device exhibited a high volume of internal connections to a broad range of endpoints, indicating potential scanning activity. Such behavior is often associated with reconnaissance efforts aimed at mapping internal infrastructure.

Darktrace / NETWORK correlated these behaviors and generated an Enhanced Monitoring model, a high-fidelity security model designed to detect activity consistent with the early stages of an attack. These high-priority models are continuously monitored and triaged by Darktrace’s Security Operations Center (SOC) as part of the Managed Threat Detection and Managed Detection & Response services, ensuring that subscribed customers are promptly alerted to emerging threats.

Darktrace detected an unusual ZIP file download alongside the anomalous script, followed by internal connectivity. This activity was correlated under an Enhanced Monitoring model.
Figure 4: Darktrace detected an unusual ZIP file download alongside the anomalous script, followed by internal connectivity. This activity was correlated under an Enhanced Monitoring model.

Darktrace Autonomous Response

Fortunately, Darktrace’s Autonomous Response capability was fully configured, enabling it to take immediate action against the offending device by blocking any further connections external to the malicious endpoint, 173.44.141[.]89. Additionally, Darktrace enforced a ‘group pattern of life’ on the device, restricting its behavior to match other devices in its peer group, ensuring it could not deviate from expected activity, while also blocking connections over 443, shutting down any unwanted internal scanning.

Figure 5: Actions performed by Darktrace’s Autonomous Response to contain the ongoing attack.

Conclusion

The rise of the MaaS ecosystem, coupled with attackers’ growing ability to customize tools and techniques for specific targets, is making intrusion prevention increasingly challenging for security teams. Many threat actors now leverage modular toolkits, dynamic infrastructure, and tailored payloads to evade static defenses and exploit even minor visibility gaps. In this instance, Darktrace demonstrated its capability to counter these evolving tactics by identifying early-stage attack chain behaviors such as network scanning and the initial infection attempt. Autonomous Response then blocked the CastleLoader IP delivering the malicious ZIP payload, halting the attack before escalation and protecting the organization from a potentially damaging multi-stage compromise

Credit to Ahmed Gardezi (Cyber Analyst) Tyler Rhea (Senior Cyber Analyst)
Edited by Ryan Traill (Analyst Content Lead)

Appendices

Darktrace Model Detections

  • Anomalous Connection / Unusual Internal Connections
  • Anomalous File / Zip or Gzip from Rare External Location
  • Anomalous File / Script from Rare External Location
  • Initial Attack Chain Activity (Enhanced Monitoring Model)

MITRE ATT&CK Mapping

  • T15588.001 - Resource Development – Malware
  • TG1599 – Defence Evasion – Network Boundary Bridging
  • T1046 – Discovery – Network Service Scanning
  • T1189 – Initial Access

List of IoCs
IoC - Type - Description + Confidence

  • 173.44.141[.]89 – IP – CastleLoader C2 Infrastructure
  • 173.44.141[.]89/service/download/data_5x.bin – URI – CastleLoader Script
  • 173.44.141[.]89/service/download/data_6x.bin – URI  - CastleLoader Script
  • wsc.zip – ZIP file – Possible Payload

References

[1] - https://blog.polyswarm.io/castleloader

[2] - https://www.recordedfuture.com/research/from-castleloader-to-castlerat-tag-150-advances-operations

[3] - https://www.pcrisk.com/removal-guides/34160-castleloader-malware

[4] - https://www.scworld.com/brief/malware-loader-castleloader-targets-devices-via-fake-github-clickfix-phishing

[5] https://www.virustotal.com/gui/ip-address/173.44.141.89/community

[6] https://thehackernews.com/2025/07/castleloader-malware-infects-469.html

[7] https://www.cryptika.com/new-castleloader-attack-using-cloudflare-themed-clickfix-technique-to-infect-windows-computers/

[8] https://www.cryptika.com/castlebot-malware-as-a-service-deploys-range-of-payloads-linked-to-ransomware-attacks/

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