The Advanced Email Attacks of Hacker Group Dark Basin
10
Jun 2020
Discover an overview of the different techniques used by Dark Basin, and how AI can respond to email impersonation attacks that other tools miss.
A report this week has revealed how the hackers-for-hire group known as ‘Dark Basin’ is targeting thousands of individuals with sophisticated and personalized email threats. The group has set up over 27,000 web pages to enable spear phishing attacks designed to harvest user credentials – most probably with the later intention of compromising the user’s account, eliciting sensitive information or wiring fraudulent payments. Among the thousands of individuals and organizations targeted are advocacy groups, journalists, elected officials, lawyers, and hedge funds.
The methods used by Dark Basin are extremely sophisticated – the emails were targeted to high-value individuals and aimed to gain their trust by falsifying known and trusted brands such as YouTube, DropBox or LinkedIn, or by posing as individual friends or colleagues. However, the reality is that thousands of businesses across the world are targeted by malicious emails crafted with this level of sophistication every single day. Darktrace regularly encounters email threats that leverage this same technique.
In fact, just last month Antigena Email neutralized an attack whereby a cyber-criminal spoofed the identity of a company’s CEO – writing in their exact style and tone – and sent out a heartfelt email to employees asking them to donate to a COVID-19 charity. The attacker had even taken the time to set up an authentic-looking web page with a donation form – all proceeds, of course, went directly into the threat-actor’s pockets.
This methodology of attack – whereby an attacker will impersonate a colleague, a boss, an IT department, or a trusted brand – has seen a significant rise this year. Prior to the outbreak of COVID-19 and the widespread adoption of remote working practices, around 20% of all malicious emails caught by Darktrace would have used some form of spoofing. Since March, we’ve seen that figure rise dramatically – 1 in 2 emails now contain some form of impersonation or spoofing. These sophisticated threats bypass the gateway on a daily basis, before being picked up and neutralized by Darktrace Cyber AI.
Figure 1: A graph showing the rise of impersonation attacks.
This trend reflects the overall success rate of this technique in the context of remote working. Last year, if you received an email from your colleague which seemed a little out of character, you might lean over your desk and ask them if they meant to send it. Today this is no longer possible. What is easier, making a phone call to check, or just clicking the link?
And it is not just individuals that these attackers are impersonating. A recent Darktrace blog gives examples where trusted presentation sites have been exploited to give a feeling of familiarity, and we’re seeing this extend to the full range of recognizable software brands we rely on for remote collaboration.
For example, we’ve seen many emails impersonating the Zoom platform, prompting the victim to accept an incoming ‘chat’ request from a colleague. The huge variety of different mechanisms that we all use to digitally communicate is playing into the hands of the criminals who suddenly find themselves with so many more methods to trick us.
Many of these malicious emails are now virtually indistinguishable from genuine communication — and there are no hard and fast rules for how employees can identify them. One email recently caught by Antigena Email attempted to coax the recipient into landing on a fake login page for the video conference application Zoom. The below illustrates how subtle the differences are between the counterfeit, and the genuine login page from the website.
Figure 2: Comparison of the counterfeit and genuine Zoom login pages.
Email filtering tools that compare emails against blacklists tend not to catch these more sophisticated and well-researched attacks. As discussed in a previous blog, many of these email threats rely on the creation of entirely new domains, which do not appear on these lists, and by default are let through.
An email security system that relies on this binary detection logic has a hard time differentiating between a legitimate email and a close copy, and no amount of employee training can guarantee complete immunity against these highly-convincing spoofing attacks. Furthermore, the ubiquity of information on social networks makes it easy for attackers to create believable emails.
However, technology powered by AI has been extremely successful in stopping these kind of advanced impersonation attacks by spotting subtle anomalies in emails that humans often miss. By understanding the human behind email communications, Antigena Email is the only email security technology that can ask whether it would be weird or unusual for a recipient to receive a given email, or visit a suspicious domain. Correlating insights around a sender’s login location, the extent of prior communication, the rarity and location of links, and over 750 other metrics, the technology detects the subtle hallmarks of an email attack that other tools miss.
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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.
Author
Dan Fein
VP, Product
Based in New York, Dan joined Darktrace’s technical team in 2015, helping customers quickly achieve a complete and granular understanding of Darktrace’s product suite. Dan has a particular focus on Darktrace/Email, ensuring that it is effectively deployed in complex digital environments, and works closely with the development, marketing, sales, and technical teams. Dan holds a Bachelor’s degree in Computer Science from New York University.
The Gartner Magic Quadrant for Email Security is designed to help organizations evaluate which email security solutions might be the best fit for their needs by providing a visual representation of the market vendors and the strengths and cautions of different vendors. We encourage our customers to read the full report to get the complete picture.
Darktrace / EMAIL has a unique AI approach to identifying threats, including NLP and behavioral analysis, instead of traditional security measures like signatures and sandboxing – providing protection against advanced attacks like Business Email Compromise (BEC) and spear phishing. We believe our AI-first approach delivers high-quality solutions that our customers trust, allowing them to stay ahead of sophisticated threats that other tools miss.
We’re proud of Darktrace’s rapid growth, geographic scale, and ability to execute effectively in the email security market, which reflect our commitment to delivering high-quality, reliable solutions that meet the evolving needs of our customers.
What do we believe makes Darktrace the fastest growing email security solution on the market?
An AI-first approach to innovation: Catching the threats others miss
As one of the founders of the ICES category, Darktrace has a long history of innovation, backed by over 200 patents. While other email security solutions are only just starting to apply machine learning (ML) techniques to outdated methods like signature analysis, reputation lists, and sandboxing, Darktrace has redefined the approach to email threat detection with its pioneering AI-driven anomaly detection engine.
Traditional ESPs often miss advanced threats because they rely on rules and signatures that focus on payloads and blindly trust known sources. This approach requires constant updates and frequently fails to detect threats like Business Email Compromise and Spear Phishing. In contrast, Darktrace / EMAIL uses advanced anomaly detection to identify the most sophisticated threats by focusing on unusual patterns and behaviors. This innovative approach has consistently delivered superior detection, stopping on average 58% of the threats that other solutions in the security stack miss.1
But our AI-first approach doesn’t stop at the inbox. At Darktrace, we transcend the limitations of traditional email security by leveraging a platform that unifies insights across multiple domains, providing robust protection against multi-domain threats. Our award-winning solutions defend the most popular attack vectors, including email, messaging, network, and identity protection. By combining signals from all domains, we establish unique behavioral profiles for each device and user, significantly enhancing detection precision.
This pioneering approach has led to introducing industry-first advancements like QR code analysis and automated incident investigations, alongside game-changing functionality including:
Microsoft Teams security with advanced messaging analysis: The ability to identify critical early phishing and insider threats across both email and Microsoft Teams messaging.
AI analyst narratives for improved end user reporting: that reduces phishing investigations by 60% by exposing unique narratives that provide the context of each received email and give feedback to each employee as they interact with their mail.2
Mailbox Security Assistant: to perform advanced behavioral browser analysis and stop malicious links within webpages, detecting and remediating 70% more malicious phishing links than traditional tools.3
AI based, autonomous data loss prevention: to immediately secure your organization from misdirected emails, insider threats, and data loss—both classified and unclassified- without any administrative overhead.
Customer trust that fuels exponential growth
With almost 5,000 customers in under 5 years, we've doubled the growth rate of other vendors in the email security market. Our rapid market penetration, fueled by customer satisfaction and pioneering technology, showcases our revolutionary approach and sets new industry standards.
Darktrace’s exceptional customer retention is fueled by an unparalleled customer experience, extensive regional support, dedicated account teams, and cutting-edge scalable technology. We pride ourselves on having a global network with local expertise, consisting of 110 worldwide offices which provide local language and technical support to offer multilingual, in-house assistance to our customer base.
Check it out – Darktrace / EMAIL has the highest percentage of 5-star ratings with a 4.8 rating on Gartner® Peer Insights™.4
Supporting every stage of your email security journey
Darktrace / EMAIL supports your security maturity journey, from first time security buyers to mature security stacks looking to augment their existing ESPs – by handling advanced threats without extensive tuning. And unlike other solutions that create a siloed and parallel solution, it works harmoniously with native email providers to create a modern email security stack. That’s why Darktrace performs well with first-time email security buyers and has strong renewal rates.
Integrating with Microsoft and Google via API, we replace traditional Secure Email Gateways (SEGs) with a modern, comprehensive email security stack. By combining approaches, our solution merges attack-centric analysis, which learns attack patterns and threat intelligence, with a business-centric approach that understands user behavior and inbox activity to deliver a unified stack that defends the entire threat spectrum – leading Darktrace to be recognized as Microsoft Partner of the year UK 2024.
Our user-friendly, self-learning AI solution requires minimal tuning and deployment, making it perfect for customers looking for a highly usable but lightly configurable solution that will accompany them throughout their lifetime as they mature their email security stack in line with the evolving threat landscape.
Learn more
Get complimentary access to the full Gartner® Magic Quadrant™ for Email Security Platforms here.
1 From September 1 – December 31 2023, 58% of the phishing emails analyzed by Darktrace / EMAIL had already passed through native spam filtering and email security controls. (Darktrace End of Year Threat Report 2023)
2 When customers deployed the Darktrace / EMAIL Outlook Add-in there was a 60% decrease in incorrectly reported phishing emails. Darktrace Internal Research, 2024
3 Once a user reports phishing that contains a link, an automated second level triage engages our link analysis infrastructure expanding the signals analyzed. Darktrace Internal Research, 2024
Cleo File Transfer Vulnerability: Patch Pitfalls and Darktrace’s Detection of Post-Exploitation Activities
File transfer applications: A target for ransomware
File transfer applications have been a consistent target, particularly for ransomware groups, in recent years because they are key parts of business operations and have trusted access across different parts of an organization that include potentially confidential and personal information about an organization and its employees.
Recent targets of ransomware criminals includes applications like Acellion, Moveit, and GoAnywhere [1]. This seems to have been the case for Cleo’s managed file transfer (MFT) software solutions and the vulnerability CVE-2024-50623.
Threat overview: Understanding Cleo file transfer vulnerability
This vulnerability was believed to have been patched with the release of version 5.8.0.21 in late October 2024. However, open-source intelligence (OSINT) reported that the Clop ransomware group had managed to bypass the initial patch in late November, leading to the successful exploitation of the previously patched CVE.
In the last few days Cleo has published a new vulnerability, CVE-2024-55956, which is not a patch bypass of the CVE-2024-50623 but rather another vulnerability. This is also an unauthenticated file write vulnerability but while CVE-2024-50623 allows for both reading and writing arbitrary files, the CVE-2024-55956 only allows for writing arbitrary files and was addressed in version 5.8.0.24 [2].
Darktrace Threat Research analysts have already started investigating potential signs of devices running the Cleo software with network traffic supporting this initial hypothesis.
Comparison of CVE-2024-50623 and CVE-2024-55956
While CVE-2024-50623 was initially listed as a cross-site scripting issue, it was updated on December 10 to reflect unrestricted file upload and download. This vulnerability could lead to remote code execution (RCE) in versions of Cleo’s Harmony, VLTrader, and LexiCom products prior to 5.8.0.24. Attackers could leverage the fact that files are placed in the "autorun" sub-directory within the installation folder and are immediately read, interpreted, and evaluated by the susceptible software [3].
CVE-2024-55956, refers to an unauthenticated user who can import and execute arbitrary Bash or PowerShell commands on the host system by leveraging the default settings of the Autorun directory [4]. Both CVEs have occurred due to separate issues in the “/Synchronization” endpoint.
Investigating post exploitation patterns of activity on Cleo software
Proof of exploitation
Darktrace’s Threat Research analysts investigated multiple cases where devices identified as likely running Cleo software were detected engaging in unusual behavior. Analysts also attempted to identify any possible association between publicly available indicators of compromise (IoCs) and the exploitation of the vulnerability, using evidence of anomalous network traffic.
One case involved an Internet-facing device likely running Cleo VLTrader software (based on its hostname) reaching out to the 100% rare Lithuanian IP 181.214.147[.]164 · AS 15440 (UAB Baltnetos komunikacijos).
This activity occurred in the early hours of December 8 on the network of a customer in the energy sector. Darktrace detected a Cleo server transferring around over 500 MB of data over multiple SSL connections via port 443 to the Lithuanian IP. External research reported that this IP appears to be a callback IP observed in post-exploitation activity of vulnerable Cleo devices [3].
While this device was regularly observed sending data to external endpoints, this transfer represented a small increase in data sent to public IPs and coupled with the rarity of the destination, triggered a model alert as well as a Cyber AI Analyst Incident summarizing the transfer. Unfortunately, due to the encrypted connection no further analysis of the transmitted data was possible. However, due to the rarity of the activity, Darktrace’s Autonomous Response intervened and prevented any further connections to the IP.
Figure 1: Model Alert Event Log show repeated connections to the rare IP, filtered with the rarity metric.
Figure 2: Shows connections to 181.214.147[.]164 and the amount of data transferred.
On the same day, external connections were observed to the external IP 45.182.189[.]225, along with inbound SSL connections from the same endpoint. OSINT has also linked this IP to the exploitation of Cleo software vulnerabilities [5].
Figure 3: Outgoing connections from a Cleo server to an anomalous endpoint.
Figure 4: Incoming SSL connections from the external IP 45.182.189[.]225.
Hours after the last connection to 181.214.147[.]164, the integration detection tool from CrowdStrike, which the customer had integrated with Darktrace, issued an alert. This alert provided additional visibility into host-level processes and highlighted the following command executed on the Cleo server:
Three days later, on December 11, another CrowdStrike integration alert was generated, this time following encoded PowerShell command activity on the server. This is consistent with post-exploitation activity where arbitrary PowerShell commands are executed on compromised systems leveraging the default settings of the Autorun directory, as highlighted by Cleo support [6]. According to external researchers , this process initiates connections to an external IP to retrieve JAR files with webshell-like functionality for continued post-exploitation [3]. The IP embedded in both commands observed by Darktrace was 38.180.242[.]122, hosted on ASN 58061(Scalaxy B.V.). There is no OSINT associating this IP with Cleo vulnerability exploitation at the time of writing.
Another device within the same customer network exhibited similar data transfer and command execution activity around the same time, suggesting it had also been compromised through this vulnerability. However, this second device contacted a different external IP, 5.45.74[.]137, hosted on AS 58061 (Scalaxy B.V.).
Like the first device, multiple connections to this IP were detected, with almost 600 MB of data transferred over the SSL protocol.
Figure 6: The Security Integration Detection Model that was triggered and the PowerShell command observed
Figure 7: Incoming connections from the external IP 38.180.242[.]122.
Figure 8: Connections to the external IP 5.45.74[.]137.
Figure 9: Autonomous Response Actions triggered during the suspicious activities
While investigating potential Cleo servers involved in similar outgoing data activity, Darktrace’s Threat Research team identified two additional instances of likely Cleo vulnerability exploitation used to exfiltrate data outside the network. In those two instances, unusual outgoing data transfers were observed to the IP 176.123.4[.]22 (AS 200019, AlexHost SRL), with around 500 MB of data being exfiltrated over port 443 in one case (the exact volume could not be confirmed in the other instance). This IP was found embedded in encoded PowerShell commands examined by external researchers in the context of Cleo vulnerability exploitation investigations.
Conclusion
Overall, Cleo software represents a critical component of many business operations, being utilized by over 4,000 organizations worldwide. This renders the software an attractive target for threat actors who aim at exploiting internet-facing devices that could be used to compromise the software’s direct users but also other dependent industries resulting in supply chain attacks.
Darktrace / NETWORK was able to capture traffic linked to exploitation of CVE-2024-50623 within models that triggered such as Unusual Activity / Unusual External Data to New Endpoint while its Autonomous Response capability successfully blocked the anomalous connections and exfiltration attempts.
Information on new CVEs, how they're being exploited, and whether they've been patched can be fast-changing, sometimes limited and often confusing. Regardless, Darktrace is able to identify and alert to unusual behavior on these systems, indicating exploitation.
Credit to Maria Geronikolou, Alexandra Sentenac, Emma Fougler, Signe Zaharka and the Darktrace Threat Research team
Darktrace’s First 6: Half-Year Threat Report 2024 highlights the latest attack trends and key threats observed by the Darktrace Threat Research team in the first six months of 2024.
Focuses on anomaly detection and behavioral analysis to identify threats
Maps mitigated cases to known, publicly attributed threats for deeper context
Offers guidance on improving security posture to defend against persistent threats
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![Incoming SSL connections from the external IP 45.182.189[.]225.](https://cdn.prod.website-files.com/626ff4d25aca2edf4325ff97/676091f13af052836b8b2ab8_676090d8352cd84c711f7144_Screenshot%25202024-12-16%2520at%252012.42.32%25E2%2580%25AFPM.png)
![Incoming connections from the external IP 38.180.242[.]122.](https://cdn.prod.website-files.com/626ff4d25aca2edf4325ff97/676091f13af052836b8b2abb_676091935b9e52a6e1bac35c_Screenshot%25202024-12-16%2520at%252012.45.35%25E2%2580%25AFPM.png)
![Connections to the external IP 5.45.74[.]137.](https://cdn.prod.website-files.com/626ff4d25aca2edf4325ff97/676091f13af052836b8b2aa3_676091abc2a7bf6fa0e9bc29_Screenshot%25202024-12-16%2520at%252012.45.47%25E2%2580%25AFPM.png)
