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
Mariana Pereira
VP, Field CISO
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23
Jun 2020
Recently in the Darktrace Blog we’ve explored how the current working conditions have resulted in a huge surge in spoofing and impersonation attacks, where attackers masquerade either as trusted colleagues or familiar brands.
These types of email attacks continue to be a successful tactic for cyber-criminals. Forever responsive and adaptive, attackers are taking advantage of the disruption to everyday operations by impersonating credible suppliers to send in fake invoices and other fraudulent emails.
How AI caught a fake invoice attack
This blog explores a string of counterfeit invoices sent to dozens of employees at a cutting-edge technology company. With valuable IP and several research labs, the company is a prime target for organized and ambitious cyber-criminals seeking maximum financial reward for their campaigns. In this particular incident, the threat-actors convincingly impersonated QuickBooks, a leading provider of book-keeping and accounting software, and part of the Intuit group which includes other recognizable brands like TurboTax and Mint.
The spoofed emails contained an invoice notification that closely imitated a legitimate monthly invoice that the organization would expect to receive from QuickBooks. If successfully delivered to the inbox, these would have appeared to come from quickbooks@notification.intuit[.]com.
The ‘invoice’ attached to these emails was actually a macro-containing Office document.
Figure 1: The malicious attachment shown in the Threat Visualizer
The source of the spoofed emails was an IP address in Italy. Since this falls outside the range of IPs that are permitted by Intuit to send mail on their behalf, this breached the SPF model breach within Antigena Email.
However, that in itself was not the main cause for Darktrace/Email’s detection – any mail server can run an SPF check. The primary factor behind the 100% anomaly score that Darktrace/Email assigned these emails was the high sender history of the email address – Darktrace was able to see that the failed SPF results were particularly suspicious against the background of SPF passes usually assigned to quickbooks@notification.intuit[.]com.
In addition, Darktrace/Email recognized that it would be highly unusual for this group of recipients, across multiple departments, to be receiving the same email from the same source – particularly of that particular subject matter. This caused the Cyber AI to hold the emails back in some cases, and in others it took the action to ‘unspoof’ the email, revealing that the invoice was not in fact from Quickbooks.
Figure 2: Five of the offending emails, deemed 100% anomalous by Darktrace/Email
The above illustrates how these emails appeared in Darktrace’s Threat Visualizer, in comparison to normal legitimate invoices below. Note the identical sender address and similar style of subject line. Had Darktrace’s AI not been analyzing every inbound email in real time, these attacks would have been highly likely to succeed.
Figure 3: Genuine invoices received from Intuit in the same week
The below is a full list of the model breaches piled onto these emails, producing the overall anomaly score of 100% seen above.
Attachment/Dangerous AttachmentAttachment/SPF Anomalous AttachmentAttachment/Spoof Sender AttachmentAttachment/Unsolicited AttachmentSpoof/Meta Popular Domain SpoofType/High Sender HistoryUnusual/Behavioral AnomalyUnusual/Connection AnomaliesValidation/SPF AnomalousValidation/SPF Fail Known Correspondent
Catching the full range of email attacks
Thankfully, the organization in question was an early adopter of a Self-Learning, AI-powered approach to email security, and the attack was contained at an early stage. But this attack is nothing extraordinary – and these kind of impersonation attempts are affecting organizations across every industry on a daily basis.
The extension of the tax season in the US this year has brought with it a widened opportunity for cyber-criminals to exploit the flurry of activity with fake invoices and other similar attacks. Predictably, a second surge of attacks targeting individuals and small businesses has been reported.
We have already seen an increase of COVID-19 related email attacks. With attackers impersonating trusted brands like Intuit’s TurboTax and QuickBooks, the necessity for defenders to adopt Cyber AI as part of their email security defense is more prevalent than ever.
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.
Patch and Persist: Darktrace’s Detection of Blind Eagle (APT-C-36)
What is Blind Eagle?
Since 2018, APT-C-36, also known as Blind Eagle, has been observed performing cyber-attacks targeting various sectors across multiple countries in Latin America, with a particular focus on Colombian organizations.
Blind Eagle characteristically targets government institutions, financial organizations, and critical infrastructure [1][2].
Attacks carried out by Blind Eagle actors typically start with a phishing email and the group have been observed utilizing various Remote Access Trojans (RAT) variants, which often have in-built methods for hiding command-and-control (C2) traffic from detection [3].
What we know about Blind Eagle from a recent campaign
Since November 2024, Blind Eagle actors have been conducting an ongoing campaign targeting Colombian organizations [1].
In this campaign, threat actors have been observed using phishing emails to deliver malicious URL links to targeted recipients, similar to the way threat actors have previously been observed exploiting CVE-2024-43451, a vulnerability in Microsoft Windows that allows the disclosure of a user’s NTLMv2 password hash upon minimal interaction with a malicious file [4].
Despite Microsoft patching this vulnerability in November 2024 [1][4], Blind Eagle actors have continued to exploit the minimal interaction mechanism, though no longer with the intent of harvesting NTLMv2 password hashes. Instead, phishing emails are sent to targets containing a malicious URL which, when clicked, initiates the download of a malicious file. This file is then triggered by minimal user interaction.
Clicking on the file triggers a WebDAV request, with a connection being made over HTTP port 80 using the user agent ‘Microsoft-WebDAV-MiniRedir/10.0.19044’. WebDAV is a transmission protocol which allows files or complete directories to be made available through the internet, and to be transmitted to devices [5]. The next stage payload is then downloaded via another WebDAV request and malware is executed on the target device.
Attackers are notified when a recipient downloads the malicious files they send, providing an insight into potential targets [1].
Darktrace’s coverage of Blind Eagle
In late February 2025, Darktrace observed activity assessed with medium confidence to be associated with Blind Eagle on the network of a customer in Colombia.
Within a period of just five hours, Darktrace / NETWORK detected a device being redirected through a rare external location, downloading multiple executable files, and ultimately exfiltrating data from the customer’s environment.
Since the customer did not have Darktrace’s Autonomous Response capability enabled on their network, no actions were taken to contain the compromise, allowing it to escalate until the customer’s security team responded to the alerts provided by Darktrace.
Darktrace observed a device on the customer’s network being directed over HTTP to a rare external IP, namely 62[.]60[.]226[.]112, which had never previously been seen in this customer’s environment and was geolocated in Germany. Multiple open-source intelligence (OSINT) providers have since linked this endpoint with phishing and malware campaigns [9].
The device then proceeded to download the executable file hxxp://62[.]60[.]226[.]112/file/3601_2042.exe.
Figure 1: Darktrace’s detection of the affected device connecting to an unusual location based in Germany.
Figure 2: Darktrace’s detection of the affected device downloading an executable file from the suspicious endpoint.
The device was then observed making unusual connections to the rare endpoint 21ene.ip-ddns[.]com and performing unusual external data activity.
This dynamic DNS endpoint allows a device to access an endpoint using a domain name in place of a changing IP address. Dynamic DNS services ensure the DNS record of a domain name is automatically updated when the IP address changes. As such, malicious actors can use these services and endpoints to dynamically establish connections to C2 infrastructure [6].
Further investigation into this dynamic endpoint using OSINT revealed multiple associations with previous likely Blind Eagle compromises, as well as Remcos malware, a RAT commonly deployed via phishing campaigns [7][8][10].
Figure 3: Darktrace’s detection of the affected device connecting to the suspicious dynamic DNS endpoint, 21ene.ip-ddns[.]com.
Shortly after this, Darktrace observed the user agent ‘Microsoft-WebDAV-MiniRedir/10.0.19045’, indicating usage of the aforementioned transmission protocol WebDAV. The device was subsequently observed connected to an endpoint associated with Github and downloading data, suggesting that the device was retrieving a malicious tool or payload. The device then began to communicate to the malicious endpoint diciembrenotasenclub[.]longmusic[.]com over the new TCP port 1512 [11].
Around this time, the device was also observed uploading data to the endpoints 21ene.ip-ddns[.]com and diciembrenotasenclub[.]longmusic[.]com, with transfers of 60 MiB and 5.6 MiB observed respectively.
Figure 4: UI graph showing external data transfer activity.
This chain of activity triggered an Enhanced Monitoring model alert in Darktrace / NETWORK. These high-priority model alerts are designed to trigger in response to higher fidelity indicators of compromise (IoCs), suggesting that a device is performing activity consistent with a compromise.
Figure 5: Darktrace’s detection of initial attack chain activity.
A second Enhanced Monitoring model was also triggered by this device following the download of the aforementioned executable file (hxxp://62[.]60[.]226[.]112/file/3601_2042.exe) and the observed increase in C2 activity.
Following this activity, Darktrace continued to observe the device beaconing to the 21ene.ip-ddns[.]com endpoint.
Darktrace’s Cyber AI Analyst was able to correlate each of the individual detections involved in this compromise, identifying them as part of a broader incident that encompassed C2 connectivity, suspicious downloads, and external data transfers.
Figure 6: Cyber AI Analyst’s investigation into the activity observed on the affected device.
Figure 7: Cyber AI Analyst’s detection of the affected device’s broader connectivity throughout the course of the attack.
As the affected customer did not have Darktrace’s Autonomous Response configured at the time, the attack was able to progress unabated. Had Darktrace been properly enabled, it would have been able to take a number of actions to halt the escalation of the attack.
For example, the unusual beaconing connections and the download of an unexpected file from an uncommon location would have been shut down by blocking the device from making external connections to the relevant destinations.
Conclusion
The persistence of Blind Eagle and ability to adapt its tactics, even after patches were released, and the speed at which the group were able to continue using pre-established TTPs highlights that timely vulnerability management and patch application, while essential, is not a standalone defense.
Organizations must adopt security solutions that use anomaly-based detection to identify emerging and adapting threats by recognizing deviations in user or device behavior that may indicate malicious activity. Complementing this with an autonomous decision maker that can identify, connect, and contain compromise-like activity is crucial for safeguarding organizational networks against constantly evolving and sophisticated threat actors.
Credit to Charlotte Thompson (Senior Cyber Analyst), Eugene Chua (Principal Cyber Analyst) and Ryan Traill (Analyst Content Lead)
Appendices
IoCs
IoC – Type - Confidence Microsoft-WebDAV-MiniRedir/10.0.19045 – User Agent
62[.]60[.]226[.]112 – IP – Medium Confidence
hxxp://62[.]60[.]226[.]112/file/3601_2042.exe – Payload Download – Medium Confidence
21ene.ip-ddns[.]com – Dynamic DNS Endpoint – Medium Confidence
diciembrenotasenclub[.]longmusic[.]com - Hostname – Medium Confidence
Darktrace’s model alert coverage
Anomalous File / Suspicious HTTP Redirect Anomalous File / EXE from Rare External Location Anomalous File / Multiple EXE from Rare External Location Anomalous Server Activity / Outgoing from Server Unusual Activity / Unusual External Data to New Endpoint Device / Anomalous Github Download Anomalous Connection / Multiple Connections to New External TCP Port Device / Initial Attack Chain Activity Anomalous Server Activity / Rare External from Server Compromise / Suspicious File and C2 Compromise / Fast Beaconing to DGA Compromise / Large Number of Suspicious Failed Connections Device / Large Number of Model Alert
Mitre Attack Mapping:
Tactic – Technique – Technique Name
Initial Access - T1189 – Drive-by Compromise Initial Access - T1190 – Exploit Public-Facing Application Initial Access ICS - T0862 – Supply Chain Compromise Initial Access ICS - T0865 – Spearphishing Attachment Initial Access ICS - T0817 - Drive-by Compromise Resource Development - T1588.001 – Malware Lateral Movement ICS - T0843 – Program Download Command and Control - T1105 - Ingress Tool Transfer Command and Control - T1095 – Non-Application Layer Protocol Command and Control - T1571 – Non-Standard Port Command and Control - T1568.002 – Domain Generation Algorithms Command and Control ICS - T0869 – Standard Application Layer Protocol Evasion ICS - T0849 – Masquerading Exfiltration - T1041 – Exfiltration Over C2 Channel Exfiltration - T1567.002 – Exfiltration to Cloud Storage
Darktrace Collaborates with Microsoft: Unifying Email Security with a Shared Vision
In today’s threat landscape, email remains the most targeted vector for cyberattacks. Organizations require not only multi-layered defenses but also advanced, integrated systems that work collaboratively to proactively mitigate threats before they cause damage
That’s why we’re proud to announce a new integration between Darktrace / EMAIL and Microsoft Defender for Office 365, delivering a Unified Quarantine experience that empowers security teams with seamless visibility, control, and response across both platforms.
This announcement builds on a strong and growing collaboration. In 2024, Darktrace was honored as Microsoft UK Partner of the Year and recognized as a Security Trailblazer at the annual Microsoft Security 20/20 Awards, a testament to our shared commitment to innovation and customer-centric security.
A Shared Mission: Stopping Threats at Machine Speed
This integration is more than a technical milestone,as it’s a reflection of a shared mission: to protect organizations from both known and unknown threats, with efficiency, accuracy, and transparency.
Microsoft Defender for Office 365 delivers a comprehensive security framework that safeguards Microsoft 365 email and collaboration workloads leveraging advanced AI, global threat intelligence and information on known attack infrastructure.
Darktrace / EMAIL complements this with Self-Learning AI that understands the unique communication patterns within each organization, detecting subtle anomalies that evade traditional detection methods.
Together, we’re delivering multi-layered, adaptive protection that’s greater than the sum of its parts.
“Our integration with Microsoft gives security teams the tools they need to act faster and more precisely to detect and respond to threats,” said Jill Popelka, CEO of Darktrace. “Together, we’re strengthening defenses where it matters most to our customers: at the inbox.”
Unified Quarantine: One View, Total Clarity
The new Unified Quarantine experience gives customers a single pane of glass to view and manage email threatsregardless of which product took action. This means:
Faster investigations with consolidated visibility
Clear attribution of actions and outcomes across both platforms
Streamlined workflows for security teams managing complex environments
“This integration is a testament to the power of combining Microsoft’s global threat intelligence with Darktrace’s unique ability to understand the ‘self’ of an organization,” said Jack Stockdale, CTO of Darktrace. “Together, we’re delivering a new standard in proactive, adaptive email security.”
A New Era of Collaborative Cyber Defense
This collaboration represents a broader shift in cybersecurity: from siloed tools to integrated ecosystems. As attackers become more sophisticated, defenders must move faster, smarter, and in unison.
Through this integration, Darktrace and Microsoft establish a new standard for collaboration between native and third-party security solutions, enhancing not only threat detection but also comprehensive understanding and proactive measures against threats.
We’re excited to bring this innovation to our customers and continue building a future where AI and human expertise collaborate to secure the enterprise.
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