Zero-Day Trojan Attack Caught by Darktrace Appliance
03
Feb 2019
Hear from a guest author how Darktrace spotted and neutralized a hidden zero-day trojan attack through our Breach Logs and Intrusion Detection System.
The following guest-authored blog post examines an advanced cyber-threat discovered by Darktrace on a customer’s network.
Previously I have talked about how Darktrace is a force multiplier for Hydrotech. As an example of this, I am sharing the anatomy of a zero-day trojan that was caught by our Darktrace system on the afternoon of Thursday, January 17. The following process was completed, in its entirety, within 20 minutes.
Remediation started within five minutes of the initial identification of the VMWare recompose process. Although the following notifications appeared at 1:38 p.m., I was working on another unrelated issue and didn’t find this information until 2:15 p.m., at which point I started my investigation and remediation efforts.
Darktrace Email Notifications @ 1:38PM EST 1/17/2018: 2019-01-17 18:37:57 UTC o365n-88.ad.hydrotech[.]com breached "Antigena / Network / External Threat / Antigena Malware File Pattern of Life Block"
FileTransfer::Exe file transfer started with filetype (application/x-dosexec)
FileTransfer::Exe file transfer started with filetype (application/x-dosexec)
2019-01-17 18:38:05 UTC o365n-88.ad.hydrotech[.]com breached "Antigena / Network / Significant Anomaly / Antigena Significant Anomaly from Client Block"
Anomalous File / Multiple EXE from Rare External Locations
2019-01-17 18:38:14 UTC o365n-88.ad.hydrotech[.]com breached "Antigena / Network / External Threat / Antigena File then New Outbound Block"
Anomalous File / EXE from Rare External Location
Review of Darktrace breach logs
The first breach log showed a file downloaded by the name “MediaTable.bin.”
This was followed shortly after by a second file downloaded by the name “OfficeActivate.bin.”
At this point I contacted the end user and told them that I was going to perform an emergency recompose within VMWare — restoring their VM to a previously known good version of the operating system — to block a suspicious software that they had downloaded 30 minutes prior. This action effectively removes any applications that have been installed on the virtual desktop computer.
After starting the recompose efforts, I then proceeded to run the URLs that I had gathered through virustotal.com to see what had been downloaded:
For the file MediaTable.bin, virustotal.com informed me that four engines detected the URL as containing malicious content.
For the file OfficeActivate.bin, virustotal.com informed me that three engines detected the URL as containing malicious content.
Review of our Intrusion Detection System on the firewall showed the following initial approval, followed by a second alert — several hours later — that changed the approval to a diagnostic of malicious, after the files had already been downloaded.
1/17/2019 13:38 File Scanned 69.163.33[.]84 Allowed OfficeActivate.bin downloaded from [http://69.163.33[.]84:8080/ELjOX2c8/OfficeActivate.bin] 1/17/2019 13:37 File Scanned 91.205.215[.]13 Allowed MediaTable.bin downloaded from [http://91.205.215[.]13:8080/O11L9Qub/MediaTable.bin] 1/17/2019 19:34 File Disposition Changed Malicious Disposition was Unknown and has been seen 1 time: OfficeActivate.bin 1/17/2019 19:34 File Disposition Changed Malicious Disposition was Unknown and has been seen 1 time: MediaTable.bin
I then input the IP addresses previously identified into the Darktrace interface to determine if any other devices had accessed them. Fortunately, I found that they had not.
Images of the event logs for those IP addresses from within Darktrace are as follows:
Event log for 69.163.33[.]84.
Event log for 91.205.215[.]13.
Further research showed that this attack was, in fact, a zero-day trojan that was first detected in the wild on January 17, 2019 — the same day as our breach. My review of the forensics for this breach, along with my review of the activity of the user utilizing the victimized virtual machine, revealed that the attack originated from this user clicking on a phishing link from their email.
I feel fairly lucky that I have Darktrace, because without it I am not sure if or when this trojan would have been identified on our network.
If there is anyone out there who has questions about Darktrace, please message me privately, as I have just become Darktrace’s biggest evangelist!
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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.
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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.
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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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![Shows connections to 181.214.147[.]164 and the amount of data transferred.](https://cdn.prod.website-files.com/626ff4d25aca2edf4325ff97/676091f33af052836b8b2b31_6760907938a8ff516ee174bf_Screenshot%25202024-12-16%2520at%252012.41.19%25E2%2580%25AFPM.png)
![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)
