Cado Security Labs (now part of Darktrace) identified a Docusign spearphishing campaign targeting tech executives. Attackers use compromised Japanese business emails and malicious links redirecting to credential-stealing sites. The campaign leverages obfuscated JavaScript to mimic legitimate login pages, aiming to steal credentials for further attacks like BEC scams.
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
Tara Gould
Malware Research Lead
Share
12
Apr 2024
Introduction: Docusign phishing attacks
Researchers from Cado Security Labs (now part of Darktrace) identified a recent Docusign spearphishing email campaign targeting tech executives. Docusign email phishing is a type of email phishing where malicious actors send fraudulent emails mimicking legitimate Docusign communications to trick recipients, typically to input credentials into an illegitimate site. These emails often appear authentic, using Docusign branding and layouts to appear as a legitimate Docusign email. Typically the emails will claim that a document is awaiting the recipient’s signature and include a link to access it. However, the link redirects users to a website designed to steal login credentials. Once these credentials have been stolen, they are likely to be used in further attacks.
Frequently, Docusign phishing campaigns will use legitimate compromised email accounts to send the phishing emails, in an effort to pass Domain Messaging Authentication Record and Conformance (DMARC) checks. Throughout this campaign, and previous Docusign campaigns, legitimate Japanese business emails are used to send the phishing emails that were previously compromised. The use of Japanese email accounts may be due to Japanese domains having a higher reputation, making them less likely to flag spam filters, as opposed to .ng or .ru.[1]
Technical analysis
The first email began with the email subject “BIYH-QPVSW-3617 is ready for your review” from “@anabuki-enter.co.jp”, with the body of the email including a “Review Document Button”. The button directs to a link hosted on “app.getresponse.com”, a legitimate marketing service. This link was down at the time of analysis, however it may have been used to track if the user opened the email or to redirect to another phishing site. Additionally, the user is prompted to visit Docusign.com and enter a security code to access the document.
Figure 1: User is promoted to login to Docusign.com
A separate email was sent with the subject “Please Docusign this document: Share transfer & Subscription Agreement_062024.docx Copy.docx_PM5235627.pdf” by a “@jaog.or.jp” address. Interestingly, the body of the email includes a legitimate email thread between multiple companies, likely to attempt to make the phishing email appear more legitimate. Included in the body of the email is a link to a malicious website containing a Javascript script “NdoGg8EElI”.
“NdoGg8EElI” is an obfuscated Javascript script that contains a series of conditional statements that are base64 encoded.
Figure 2
The script begins with an if statement to check if “https://xx[.]yperbole9[.]com/BrfMyTrgSAvPiJtOFWxtG0clXO/” equals “nomatch”, which it obviously doesn’t, this might just be junk code, along with the subsequent document.write().
Following the document.write blob is the same if statement but with !== this time.
Figure 3
This time the conditions will be true, executing the subsequent code.
Figure 4
Const “AraaqOIGqY” takes the current URL hostname.
Const “aEKzPLUWtg” creates a new URL from base64 which is the “https://xx[.]yperbole9[.]com/BrfMyTrgSAvPiJtOFWxtG0clXO/” domain.
Const “zbwXTqjqwH” checks the URL hostname against “aEKzPLUWtg” and if it doesn’t match it takes the TLD and SLD from the decoded URL.
Next checks compare the hostname and pathname to check if the current page is the same as the base64 domain (https://xx[.]yperbole9[.]com/BrfMyTrgSAvPiJtOFWxtG0clXO/) and if they do the next base64 block executes.
The block contains HTML with a captcha check and a Gmail background image, in an effort to look like a legitimate Google Workspace log in page. The user is then redirected to another phishing page hosted on “blegabouc[.]com”, which was down at the time of analysis but likely prompted the user to enter their credentials.
Figure 5: User promoted to enter Gmail credentials
The next block compares the hostname and pathname to check if they do not match the current page, if this is true a 404 HTML page occurs.
Figure 6
Finally, “zbwXTqjqwH” is checked to not equal “AraaqOIGqY”, which checks if the hostname and decoded base64 URL are not equal. If true the same base64 encoded HTML 404 page occurs again.
The goal of these Docusign campaigns are to steal credentials from businesses that can be used for further attacks including BEC scams, or to sell on marketplaces.
Key takeaways
Docusign phishing attacks are an ongoing issue facing organizations, as they exploit the trusted nature of electronic signature platforms to deceive recipients into sending their credentials. These attacks often leverage familiar branding, compromised email accounts, and tactics like embedding fake email threads to appear legitimate.
To protect against such phishing attempts, it is crucial to be cautious when receiving unsolicited Docusign emails, especially when they ask for urgent action. Users should always:
Mark emails that don’t pass SPF, DKIM and/or DMARC as spam / suspicious.
Educate employees on how to spot phishing emails and actions to take when they identify one.
Verify the sender’s email address and don’t rely on the alias that’s used by mail clients.
Avoid clicking links or opening attachments on unsolicited emails.
Enable 2FA (2-Factor Authentication) on all accounts.
Verify through Docusign account, whether the document is legitimate, by logging into Docusign and accessing Documents or using the Access Code. Docusign Verify can be used to validate the e-signature.
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.
React2Shell Reflections: Cloud Insights, Finance Sector Impacts, and How Threat Actors Moved So Quickly
This blog breaks down how attackers rapidly weaponized the React2Shell vulnerability, with a particular focus on cloud‑native financial environments. Drawing on Darktrace’s honeypot research, it explores emerging threat actor tooling, exploitation timelines, and why behavioral‑anomaly‑led security is critical in today’s cloud landscape.
Hola VPN Abuse: From Proxy Traffic to Malware and Cryptomining
Introduction
In enterprise environments, non-compliant software traffic can introduce unexpected exposure by creating unmanaged paths for outbound connectivity. Hola VPN is a notable example because of its peer-to-peer design, which can effectively turn user devices into routing or exit nodes for other parties’ traffic, shifting the risk profile from that of a traditional virtual private network (VPN) to something closer to a distributed proxy.
As a result, the appearance of Hola-related activity, whether from prior installation or unintended background connections, should be treated with caution. Such activity may provide a foothold for malicious behavior, including lateral movement or command-and-control communication.
This blog explores how Hola-associated activity appeared as part of broader patterns of suspicious behavior observed across the Darktrace customer base.
The campaign
In February and March 2026, Darktrace observed similar anomalous activity across multiple customer environments, with affected devices showing consistent behavioral patterns. These included connections to multiple *.hola[.]org endpoints using Hola-related user agents, suggesting interaction with Hola infrastructure rather than isolated or incidental traffic.
Following these connections, affected customer environments showed downloads of suspicious executable files from rare external endpoints 188.241.219[.]55 and 184.241.218[.]111. Both endpoints have been flagged as potentially malicious by open-source intelligence (OSINT) [1][2].
These downloads were conducted using consistent user agents across impacted customers, specifically ‘Hola svc_js_win32/1.249.408’ and ‘Hola svc_js_win32/1.251.389’, suggesting a possible association with Hola-related activity.
Notably, this pattern aligns with recent reporting that, in some cases, Hola distributed an undeclared executable component, me[.]exe, which was later assessed to be a likely Monero-mining binary introduced via a compromised delivery pipeline [3].
Case Study 1
Darktrace first observed a new device on January 19, 2026, within a customer environment based in the Europe, Middle East, and Africa (EMEA) region. On the same day it appeared on the network, the device communicated with multiple pieces of Hola VPN-linked infrastructure before downloading a binary from a hola[.]org subdomain.
Figure 1: Cyber AI Analyst investigation highlighting Hola VPN service activity potentially associated with subsequent HTTP command-and-control (C2) connections.
Subsequent Darktrace telemetry revealed a recurring pattern of activity from the day the device was first observed through to March 4, 2026. During this period, the device repeatedly issued HTTP GET requests to the URI /bwfile?size=1048576, each returning a 200 OK response, indicating successful file retrieval.
This behavior was accompanied by a POST request to /bwfile, followed by an additional GET request for a significantly larger file at /bwfile?size=26214400, suggesting a deliberate and structured file transfer pattern.
Notably, the binary download activity was not tied to a single static host. Instead, it was observed across multiple URLs that changed over time while remaining within the same hola[.]org domain. This pattern suggests the use of rotating or distributed delivery infrastructure rather than a fixed endpoint.
Figure 2: Variation in URLs over time within the same hola[.]org domain, indicating the use of dynamically changing endpoints.
Across these events, the activity was consistently associated with the user agent Hola svc_js_win32/1.249.408, further linking the traffic to Hola-related service components. Amid these persistent and unusual connections, on February 22, Darktrace observed the device connecting to 188.241.219[.]55/proxy-peer-windows-amd64[.]exe, resulting in the download of an executable file.
Figure 3: File transfer event showing the download of an executable from the rare external endpoint 188.241.219[.]55.
Based on its file hash, the downloaded file was assessed as a likely Trojan downloader [4], with import hash (imphash) values showing similarities to samples linked to Vidar, Rhadamanthys, and Stealc according to OSINT [5]. Overall, this sequence of activity suggests that Hola-related connectivity may have been leveraged as part of a broader malware delivery chain.
Darktrace’s Autonomous Response
Due to the highly unusual activity observed, Darktrace Autonomous Response was triggered by the device’s behavior. However, as the customer deployment was configured in “Human Confirmation” mode, manual approval was required before any action could be taken.
Had the deployment been set to “Fully Autonomous” mode, Darktrace would have automatically:
Blocked connections to the associated ports and external endpoints
Prevented all outgoing network connections from the device
Enforced the device’s established ‘pattern of life’, allowing normal activity to continue while restricting any anomalous behavior
Figure 4: Example of a Darktrace Autonomous Response model highlighting the action that would have been taken, demonstrating how the system identifies anomalous behavior and applies targeted containment measures to restrict suspicious network activity.
Case Study 2
While the first case focused on anomalous activity from a newly observed device, Darktrace also identified cases in which devices had already been communicating with Hola-related endpoints prior to the suspected campaign. This may suggest pre-existing Hola usage within the environment, potentially increasing exposure and creating an avenue for subsequent suspicious activity.
One case involved three devices within a customer network based in the Americas (AMS). In this instance, a different payload was identified: me[.]exe, a potentially malicious cryptocurrency miner also referred to as HolaMonitorService[.]exe [6][7]. The downloads were observed from infrastructure similar to that seen in Case 1, including an IP address within the same 188.241.0.0/16 subnet.
Connections to *.hola[.]org, alongside the use of potential Hola-related user agents consistent with those in Case 1, were also identified, further suggesting a link between the observed activity and Hola-associated infrastructure.
Darktrace observed activity indicative of unusual VPN usage on the first affected device on February 2, followed by telemetry suggesting potential Tor usage. This was later followed by the download of me[.]exe on March 10 from 188.241.218[.]111. Notably, this device was the earliest among the three within the deployment to exhibit the presence of the suspicious executable.
Figure 5: Cyber AI Analyst detection highlighting the download of a suspicious executable from a similar external endpoint in a separate deployment.
On March 5, 2026, the second affected device exhibited a slightly different progression, initiating connections to http-test1[.]hola[.]org using the user agent ‘hola_get’. This activity was followed by the download of me[.]exe from the same endpoint on March 13, consistent with the broader pattern of Hola-related downloads observed across the environment.
Figure 6: Example of Hola VPN-related connectivity observed on the network prior to the suspected campaign, indicating pre-existing usage that may have contributed to subsequent activity.
The final affected device within this customer’s network demonstrated a more limited but related pattern, also downloading me[.]exe on March 17 using the same ‘hola_get’ user agent.
While the earlier Hola VPN usage observed across the deployment may not have been directly related to the suspected malware campaign, it may nonetheless have contributed to reduced visibility. The presence of pre-existing Hola-related traffic could have obscured malicious activity, making it more difficult to distinguish legitimate usage from attacker-driven behavior and, in turn, hindering the timely identification of the emerging compromise.
Darktrace’s Autonomous Response
For this deployment, the customer had their Autonomous Response capability configured in “Fully Autonomous” mode, allowing Darktrace to take action without human intervention. As a result, the system was able to autonomously disrupt the activity as soon as relevant events were identified through model detections.
Figure 7: Darktrace Autonomous Response actions taken against suspicious activity linked to Hola VPN.
Suspected cryptomining activity
As previously noted, some of the observed executable payloads appear to be linked to cryptomining malware. Across a subset of affected customer environments, this assessment was further supported by subsequent device activity consistent with Monero mining. Affected devices established follow-on connections to multiple external endpoints aligned with known mining infrastructure, indicating post-download execution.
Considering the broader sequence of activity, this pattern may point to a wider form of abuse in which legitimate VPN-related traffic is used to mask or facilitate malicious behavior following compromise.
On several devices, the download of executable files, including a newly observed peer[.]exe, was followed by alerts indicative of cryptocurrency mining activity. Mining-related credentials such as ‘x’ were observed using the Minergate protocol to communicate with endpoints within the 89.125.255.0/24 subnet and 188.241.218[.]111, the same endpoint involved in earlier download activity. Additional credentials appeared to reflect device-specific CPU identifiers, for example ‘12th Gen Intel(R) Core (TM) i5-1235U’.
Observed mining methods included login, submit, and job, consistent with active participation in a pool-based mining workflow rather than passive or incidental contact. The login method indicates that the host authenticated to the mining service as a worker, job reflects the assignment of computational tasks, and submit shows completed work being returned to the pool [8]. This sequence suggests that affected devices were actively contributing processing resources as part of an unauthorized distributed mining operation.
The presence of unauthorized cryptominers can lead to degraded system performance and reduced device stability. Beyond the immediate resource impact, such activity often serves as an indicator of a broader compromise rather than an isolated issue. This may increase the risk of further malware deployment, persistence mechanisms, and lateral movement, particularly in environments where the initial intrusion has not been fully contained.
Conclusion
Across affected environments, detections such as unusual VPN usage, connections to Hola infrastructure, anomalous HTTP activity, suspicious file downloads, and subsequent cryptomining behavior were linked into a single, evolving incident narrative. This aggregation provided a clearer view of attack progression, enabling security teams to understand not just isolated alerts, but the full sequence of compromise from initial contact through to post-exploitation.
Ultimately, these activities show that the risk posed by non-compliant software such as Hola VPN can extend far beyond simple policy violations. What began as traffic to Hola-related infrastructure was, in multiple cases, followed by behavior suggesting deliberate misuse, including suspicious executable downloads using Hola-related user agents and, in some instances, evidence of active cryptomining. These were not isolated anomalies, but elements of a broader pattern in which seemingly benign proxy or VPN-related communications may have created a pathway for malicious delivery and unauthorized resource exploitation.
The significance of this activity lies not only in the downloads or mining, but in what it reveals about an attacker’s ability to blend malicious operations into traffic associated with software that may already have a foothold in the environment. When unapproved software operates within an enterprise, it can reduce visibility, blur the distinction between legitimate and malicious traffic, and create opportunities to extend compromise in ways that are persistent and difficult to detect. Darktrace’s anomaly-based approach enables these behavioral distinctions to be identified, regardless of whether the device is new or long established within the network.
Credit to Min Kim (Associate Principal Analyst), Priya Thapa (Senior Cyber Analyst) Edited by Ryan Traill (Content Manager)
![Variation in URLs over time within the same hola[.]org domain, indicating the use of dynamically changing endpoints.](https://cdn.prod.website-files.com/626ff4d25aca2edf4325ff97/6a304bdeff111215c0436931_Screenshot%202026-06-15%20at%2012.00.43%E2%80%AFPM.png)
![File transfer event showing the download of an executable from the rare external endpoint 188.241.219[.]55.](https://cdn.prod.website-files.com/626ff4d25aca2edf4325ff97/6a304c2468d20aeff16a2721_Screenshot%202026-06-15%20at%2012.01.53%E2%80%AFPM.png)
