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August 3, 2022

The Risks of Remote Access Tools

Discover how remote access tools in exploitations across OT/ICS and corporate environments benefit from Darktrace's product suite.
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
Dylan Hinz
Cyber Analyst
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03
Aug 2022

Understanding remote access tools

In 2022, remote access tools continue to provide versatile support to organizations. By controlling devices remotely from across the globe, IT teams save on response costs, travel times, and can receive remote support from external parties like contractors [1 & 2]. This is particularly relevant in cases involving specialty machines such as OT/ICS systems where physical access is sometimes limited. These tools, however, come with their own risks. The following blog will discuss these risks and how they can be addressed (particularly in OT environments) by looking at two exploit examples from the popular sphere and within the Darktrace customer base. 

What are remote access tools?

One of the most popular remote tools is TeamViewer, a comprehensive videoconferencing and remote management tool which can be used on both desktop and handheld devices[3]. Like other sophisticated tools, when it works as intended, it can seem like magic. However, remote access tools can be exploited and may grant privileged network access to potential threat actors. Although TeamViewer needs to be installed on both perpetrator and victim devices, if an attacker has access to a misconfigured TeamViewer device, it becomes trivial to establish a foothold and deploy malware. 

How secure is remote access?

Security vulnerabilities in remote access tools

In early 2021, remote access tooling was seen on a new scale against the City of Oldsmar’s water treatment plant [4] (Figure 1). Oldsmar manages chemical concentration levels in the water for a 15,000-person city. The water treatment plant had been using TeamViewer to allow employees to share screens and work through IT issues. However, in February an employee noticed he had lost control of his mouse cursor. Initially he was unconcerned; the employee assumed that the cursor was being controlled by his boss, who regularly connected to the computer to monitor the facility’s systems. A few hours later though, the employee again saw his cursor moving out of his control and this time noticed that it was attempting to change levels of sodium hydroxide in the water supply (which is extremely dangerous for human consumption). Thankfully, the employee was able to quickly spot the changes and return them to their normal level. When looking back at the event, the key question posed by officials was where exactly the vulnerability was located in their security stack. [5]. The answer was unclear.

Photograph of compromised water plant in Florida 
Figure 1: Photograph of compromised water plant in Florida 

Tactics and strategies

When attackers get initial network access, the primary challenge for any enterprise is identifying a) that a device compromise has happened and b) how it happened. These were the same challenges seen in the Oldsmar attack. When the first physical signs of compromise occurred (cursor movement), the impacted user was still unsure whether the activity was malicious. A detailed investigation from Dragos revealed the how: evidence of a watering hole, reconnaissance activity a month prior, a targeted variant of the Tofsee botnet, and the potential presence of two separate threat actors [6 & 7]. The answer to both questions pointed to a complex attack. However, with Darktrace these questions become less important. 

How Darktrace stops compromised remote access

Darktrace does not rely on signatures but instead has AI-based models for live detection of these tools and anomalies within the wider network. Regardless of the security ‘hole’, live detection gives security teams the potential to respond in near-live time.

According to Darktrace’s Chief Product Officer, Max Heinemeyer, the Oldsmar attack was possible because it “Abused off-the-shelf tools that were already used by the client, specifically TeamViewer. This tactic, which targeted the domain controller as the initial vector, made the malware deployment easy and effective.” [8]. 

Darktrace has multiple DETECT models to provide visibility over anomalous TeamViewer or remote access tool usage:

·      Compliance / Incoming Remote Access Tool

·      Compliance / Remote Management Tool On Client

·      Compliance / Remote Management Tool On Server

·      Device / Activity Identifier / Teamviewer 

General incoming privileged connections:

·      Compliance / Incoming Remote Desktop

·      Compliance / Incoming SSH

Industrial DETECT can also highlight any new or unusual changes in ICS/OT systems:

·      ICS / Incoming ICS Command

·      ICS / Incoming RDP And ICS Commands

·      ICS / Uncommon ICS Error

Darktrace gives security teams the opportunity for a proactive response, and it is up to those teams to utilize that opportunity. In recent months our SOC Team have also seen remote access controls being abused for high-profile threats. In one example, Darktrace detected a ransomware attack supported by the installation of AnyDesk. 

Initial detection of compromise

In May a company’s mail server was detected making multiple external requests for an unusual file ‘106.exe’ using a PowerShell agent (6b79549200af33bf0322164f8a4d56a0fa08a5a62ab6a5c93a6eeef2065430ce). Although some requests were directed to sinkholes, many were otherwise successful. Subsequently a DDL file with hash f126ce9014ee87de92e734c509e1b5ab71ffb2d5a8b27171da111f96f3ba0e75 (marked by VirusTotal as malicious) was downloaded. This was followed by the installation of AnyDesk: a remote access tool likely deployed for backdoor purposes during further compromises. It is clear the threat actor then moved on to reconnaissance, with new Mimikatz use and a large volume of ICMP and SMBv.1 scanning sessions using a default credential. DCE-RPC calls were also made to the Netlogon service, suggesting a possible attempt to exploit 2020’s Zerologon vulnerability (CVE-2020-1472) [9]. When the customer then discovered a ransom note pertaining to LV (repurposed REvil), Darktrace analysts helped them to re-configure Darktrace RESPOND and turn it to active rather than human confirmation mode (Figure 2). 

Figure 2: Capture of LV ransom note provided by customer

Whilst in this instance the tool was not used for initial access, it was still an important contingency tool to ensure the threat actor’s persistency as the customer tried to respond to the ongoing breach. Yet it was the visibility provided by Darktrace model detection and changes to RESPOND configuration which ensured the customer kept up with this actor and reduced the impact of the attack. 

Looking back at Oldsmar, it is clear that being aware of remote access tools is only half the battle. More importantly, most organizations are asking if their use in attacks can be prevented in the first place. As an off-the-shelf tool, restricting TeamViewer use seems like an easy solution but such tools are often essential for maintenance and support operations. Even if limited to privileged users, these accounts are also subject to potential compromise. Instead, companies can take a large-scale view and consider the environment in which the Oldsmar attack occurred. 

How IT & OT convergence complicated this attack

In this context, the separation of OT and IT systems is a potential solution - if attackers cannot access at-risk systems, then they also cannot attack those systems. However, with recent discourse around the IT-OT convergence and increased use of IoT devices, this separation is increasingly challenging to implement [10]. Complex networking designs, stringent patching requirements and ever-changing business/operational needs are all big considerations when establishing industrial security. In fact, Tenable’s CEO Amit Yoran encouraged less separation following Oldsmar: “There’s business reasons and efficiency reasons that you might want to connect those to be able to predict when parts are going to fail or when outages are going to occur [sic].” [11]. 

When neither addressing remote access use or industrial set-up provides a quick solution, then security teams need to look to third-party support to stop similar attacks. In addition to Darktrace DETECT, our Darktrace PREVENT range with PREVENT/Attack Surface Management (ASM) can also alert security teams to internet-facing devices at risk of remote access exploitation. ASM actively queries the Shodan API for open ports on company websites and exposed servers. This highlights those assets which might be vulnerable to this type of remote access.   

Conclusion

In conclusion, TeamViewer and other remote access tools offer a lot of convenience for security teams but also for attackers. Attackers can remotely access important systems including those in the industrial network and install malware using remote access tools as leverage. Security teams need to know both their normal authorized activities and how to enforce them. With Darktrace DETECT, the tools are given transparency, with Darktrace RESPOND they can be blocked, and now Darktrace PREVENT/ASM helps to mitigate the risk of attack before it happens. As the professional world continues to embrace hybrid working, it becomes increasingly crucial to embrace these types of products and ensure protection against the dangers of unwanted remote access. 

Thanks to Connor Mooney for his contributions to this blog.

Appendices

References 

[1] https://goabacus.com/advantages-and-disadvantages-of-remote-access-service/ 

[2] https://blog.ericom.com/advantages-of-remote-access/ 

[3] https://www.teamviewer.com/en/documents/ 

[4] https://www.wired.com/story/oldsmar-florida-water-utility-hack/ 

[5 & 11] https://www.bankinfosecurity.com/ot-it-integration-raises-risk-for-water-providers-experts-say-a-18841 

[6] https://www.dragos.com/blog/industry-news/a-new-water-watering-hole/ 

[7] https://www.dragos.com/blog/industry-news/recommendations-following-the-oldsmar-water-treatment-facility-cyber-attack/

[8] https://customerportal.darktrace.com/darktrace-blogs/get-blog/53  

[9] https://www.crowdstrike.com/blog/cve-2020-1472-zerologon-security-advisory/

[10] https://www.mckinsey.com/business-functions/operations/our-insights/converge-it-and-ot-to-turbocharge-business-operations-scaling-power

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
Dylan Hinz
Cyber Analyst

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November 27, 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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