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May 28, 2019

[Part 2] Top Cyber Hygiene Issues Leading to a Breach

Spotting cyber hygiene issues caused by a lapse of attention requires AI tools that alert critical changes to network activity. Read part two here!
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
Max Heinemeyer
Global Field CISO
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28
May 2019

Read the first part: Part one — A perimeter in ruins

Earlier this month, I discussed some of the most critical challenges that today’s institutions face in their efforts to reinforce the network perimeter. Eliminating common attack vectors, from unauthorized uploads in the cloud to outdated protocol usage on-premise, is an essential step toward a more secure digital future.

Ultimately, however, I concluded that even flawless cyber hygiene at the perimeter will never be a panacea for all possible cyber-threats, since defenders cannot possibly address vulnerabilities about which they aren’t yet aware. Building strong borders is vital, clearly, but as attackers continue to launch novel attacks, even 50-foot walls are imperiled by 50-foot ladders.

Of course, such concerns become merely academic when your walls aren’t placed correctly, or watched attentively, or expanded when the digital estate grows. For countless employees and organizations alike, the allure of convenience has weakened the perimeter in all of these ways and more, rendering the work of cyber-criminals exponentially easier. Yet given the complexity of the modern enterprise, discovering exactly where users have cut corners is often difficult for human security teams alone. Spotting cyber hygiene issues caused by a lack of due diligence — like the five detailed below — therefore requires AI tools that alert on critical changes to network activity in real time.

Issue #6: Not keeping an inventory of hardware on the network

As all manner of non-traditional IT makes its way into workplaces around the world, keeping an inventory of these seamlessly integrated devices often proves an arduous undertaking, one that many organizations shirk altogether. Between app-controlled thermostats and smart refrigerators, connected cameras and Bluetooth sensors, few security teams possess a rigorous list of the hardware under their care.

Yet attaining 100% network visibility is a prerequisite to any viable security posture. Attackers are increasingly targeting poorly secured IoT devices to bypass the perimeter at its weakest points, before moving laterally to compromise more sensitive databases and machines. By analyzing all traffic from the entire enterprise, Darktrace detects when new devices come online and alert on any unusual activity from them with its AI models, some of which are:

  • Device / New Device with Attack Tools
  • Unusual Activity / Anomalous SMB Read & Write from New Device
  • Unusual Activity / Sustained Unusual Activity from New Device
  • Unusual Activity / Unusual Activity from New Device

Issue #7: Using corporate devices for private use

While the divide between corporate and private networks is a primary facet of cyber hygiene, few employees are immune to the temptation and convenience of using company devices for personal use. Whether it’s torrenting movies, visiting social media websites, or checking personal email accounts during the workday, these activities all expose carefully guarded corporate environments to ones that are far less secure. At the same time, many organizations lack visibility over their own online traffic, preventing their security teams from catching such risky behavior until it’s already too late.

Employees have also been known to violate internal compliance policies by downloading unauthorized software for private purposes, which introduces serious security risks and opens the door for supply chain attacks. Darktrace has detected a plethora of threats related to such downloads across our customer base, including outdated software, network scanners, BitTorrent clients, and crypto-mining programs. Such compliance issues trigger a number of Darktrace’s behavioral models, for example:

  • Anomalous File / EXE from Rare External Location
  • Anomalous File / Incoming RAR File
  • Compliance / BitTorrent
  • Compliance / Crypto Currency Mining Activity

To bypass compliance policies and access resources blocked by network administrators, employees often turn to VPNs as well as onion routing services like Tor, which facilitate anonymous communication. These services are equivalent to inhibiting security controls on the offending device; consequently, companies must have the ability to detect and terminate them whenever they are used on the network. Because Darktrace provides 100% visibility across the digital infrastructure, it can flag private VPN and Tor sessions with the following example models:

  • Anomalous Connection / New Outbound VPN
  • Compliance / Privacy VPN
  • Compliance / Tor Usage

Darktrace detected one such case earlier this year wherein a corporate device connected to a third-party VPN. Although this activity is not inherently risky or threatening in all situations, Darktrace’s understanding of the company’s network revealed that the device was the only one using the VPN — strongly suggesting a compliance violation. Moreover, when the device was not using the VPN service, it was seen making a large amount of HTTP post requests to another rare destination and displaying other signs of infection. It turned out that the device was infected with the elusive Ursnif trojan.

Figure 1: Darktrace’s external site summary showing that only one device in the network connected to the VPN.

Issue #8: Lack of strong access management

Ensuring that only rightful users have access to private company resources is a foundational component of cyber security. Yet as these users and their privileges continuously evolve, maintaining strong access management can be time-consuming and difficult.

Out of all the users in the network, the accounts to which the most attention should be paid are those with administrator or root privileges. While it is common to keep a tight control on high-privilege accounts, there are still organizations that find it hard to manage the access control well, making their devices more vulnerable to both malware and insider threats. In fact, even well-intentioned insiders can jeopardize the organization in the absence of strong access management, such as employees who download unauthorized software without understanding its associated risks.

Darktrace has a list of models to detect the unusual usage of credentials, including:

  • User / New Admin Credentials on Client
  • User / Overactive User Credential
  • SaaS / Unusual SaaS Administration

Issue #9: TFTP Usage

Trivial File Transfer Protocol (TFTP) is an application layer protocol commonly employed to transfer files between devices. Due to its relatively simplistic design and easy implementation, TFTP was very popular in the past. In the context of today’s sophisticated cyber-threats, however, TFTP has become highly insecure. Among the protocol’s numerous weaknesses from a cyber hygiene perspective is its lack of authentication mechanisms, a flaw which allows essentially anyone to read and write resources on the exposed device.

Darktrace’s Compliance / External TFTP model enables network administrators to detect any incoming TFTP connections from external IP addresses that don’t normally connect to the network. Crucially, Darktrace AI’s understanding what constitutes “normal” versus “abnormal” for each particular network serves to differentiate the most serious threats, as TFTP connections from a rare IP address are much more likely to be malicious than similar connections between known IP addresses on the network.

TFTP is just one example of insecure protocol usage – Darktrace monitors for the abnormal usage of various other attack-prone protocols as well. Another example is Telnet.

Issue #10: Unencrypted data transferred between internal and external devices

While encrypting communication can be a hassle, cleartext messages are liable to be intercepted or even altered by malicious actors — with potentially devastating ramifications. Indeed, Darktrace’s Compliance / FTP / Unusual Outbound FTP model has frequently flagged credentials being sent via unencrypted channels, which attackers could have used to access privileged resources within the company’s network.

In the first few months of 2019, Darktrace detected an unusual connection made to an external device on port 1414 using the IBM WebSphere MQ Protocol. When potentially sensitive information was transmitted in cleartext, Darktrace AI alerted the customer in real time.

Figure 2: Packet capture showing that potential sensitive information was captured

Sacrificing convenience for security in these most egregious cases remains the foundation of robust cyber hygiene, whether that means not torrenting Shrek 2 on a work laptop or taking inventory of the smart juicer in the office kitchen. Of course, just as no perimeter defenses are formidable enough to keep motivated attackers at bay, so too is there no level of due diligence sufficient to close off all possible attack vectors or ensure that all employees are compliant with internal policies. With cyber AI defenses like Darktrace, security teams have an extra set of eyes watching out for poor cyber hygiene practices across the entire digital infrastructure, empowering them to grow those infrastructures with confidence.

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
Max Heinemeyer
Global Field CISO

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May 16, 2025

Catching a RAT: How Darktrace neutralized AsyncRAT

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What is a RAT?

As the proliferation of new and more advanced cyber threats continues, the Remote Access Trojan (RAT) remains a classic tool in a threat actor's arsenal. RATs, whether standardized or custom-built, enable attackers to remotely control compromised devices, facilitating a range of malicious activities.

What is AsyncRAT?

Since its first appearance in 2019, AsyncRAT has become increasingly popular among a wide range of threat actors, including cybercriminals and advanced persistent threat (APT) groups.

Originally available on GitHub as a legitimate tool, its open-source nature has led to widespread exploitation. AsyncRAT has been used in numerous campaigns, including prolonged attacks on essential US infrastructure, and has even reportedly penetrated the Chinese cybercriminal underground market [1] [2].

How does AsyncRAT work?

Original source code analysis of AsyncRAT demonstrates that once installed, it establishes persistence via techniques such as creating scheduled tasks or registry keys and uses SeDebugPrivilege to gain elevated privileges [3].

Its key features include:

  • Keylogging
  • File search
  • Remote audio and camera access
  • Exfiltration techniques
  • Staging for final payload delivery

These are generally typical functions found in traditional RATs. However, it also boasts interesting anti-detection capabilities. Due to the popularity of Virtual Machines (VM) and sandboxes for dynamic analysis, this RAT checks for the manufacturer via the WMI query 'Select * from Win32_ComputerSystem' and looks for strings containing 'VMware' and 'VirtualBox' [4].

Darktrace’s coverage of AsyncRAT

In late 2024 and early 2025, Darktrace observed a spike in AsyncRAT activity across various customer environments. Multiple indicators of post-compromise were detected, including devices attempting or successfully connecting to endpoints associated with AsyncRAT.

On several occasions, Darktrace identified a clear association with AsyncRAT through the digital certificates of the highlighted SSL endpoints. Darktrace’s Real-time Detection effectively identified and alerted on suspicious activities related to AsyncRAT. In one notable incident, Darktrace’s Autonomous Response promptly took action to contain the emerging threat posed by AsyncRAT.

AsyncRAT attack overview

On December 20, 2024, Darktrace first identified the use of AsyncRAT, noting a device successfully establishing SSL connections to the uncommon external IP 185.49.126[.]50 (AS199654 Oxide Group Limited) via port 6606. The IP address appears to be associated with AsyncRAT as flagged by open-source intelligence (OSINT) sources [5]. This activity triggered the device to alert the ‘Anomalous Connection / Rare External SSL Self-Signed' model.

Model alert in Darktrace / NETWORK showing the repeated SSL connections to a rare external Self-Signed endpoint, 185.49.126[.]50.
Figure 1: Model alert in Darktrace / NETWORK showing the repeated SSL connections to a rare external Self-Signed endpoint, 185.49.126[.]50.

Following these initial connections, the device was observed making a significantly higher number of connections to the same endpoint 185.49.126[.]50 via port 6606 over an extended period. This pattern suggested beaconing activity and triggered the 'Compromise/Beaconing Activity to External Rare' model alert.

Further analysis of the original source code, available publicly, outlines the default ports used by AsyncRAT clients for command-and-control (C2) communications [6]. It reveals that port 6606 is the default port for creating a new AsyncRAT client. Darktrace identified both the Certificate Issuer and the Certificate Subject as "CN=AsyncRAT Server". This SSL certificate encrypts the packets between the compromised system and the server. These indicators of compromise (IoCs) detected by Darktrace further suggest that the device was successfully connecting to a server associated with AsyncRAT.

Model alert in Darktrace / NETWORK displaying the Digital Certificate attributes, IP address and port number associated with AsyncRAT.
Figure 2: Model alert in Darktrace / NETWORK displaying the Digital Certificate attributes, IP address and port number associated with AsyncRAT.
Darktrace’s detection of repeated connections to the suspicious IP address 185.49.126[.]50 over port 6606, indicative of beaconing behavior.
Figure 3: Darktrace’s detection of repeated connections to the suspicious IP address 185.49.126[.]50 over port 6606, indicative of beaconing behavior.
Darktrace's Autonomous Response actions blocking the suspicious IP address,185.49.126[.]50.
Figure 4: Darktrace's Autonomous Response actions blocking the suspicious IP address,185.49.126[.]50.

A few days later, the same device was detected making numerous connections to a different IP address, 195.26.255[.]81 (AS40021 NL-811-40021), via various ports including 2106, 6606, 7707, and 8808. Notably, ports 7707 and 8808 are also default ports specified in the original AsyncRAT source code [6].

Darktrace’s detection of connections to the suspicious endpoint 195.26.255[.]81, where the default ports (6606, 7707, and 8808) for AsyncRAT were observed.
Figure 5: Darktrace’s detection of connections to the suspicious endpoint 195.26.255[.]81, where the default ports (6606, 7707, and 8808) for AsyncRAT were observed.

Similar to the activity observed with the first endpoint, 185.49.126[.]50, the Certificate Issuer for the connections to 195.26.255[.]81 was identified as "CN=AsyncRAT Server". Further OSINT investigation confirmed associations between the IP address 195.26.255[.]81 and AsyncRAT [7].

Darktrace's detection of a connection to the suspicious IP address 195.26.255[.]81 and the domain name identified under the common name (CN) of a certificate as AsyncRAT Server
Figure 6: Darktrace's detection of a connection to the suspicious IP address 195.26.255[.]81 and the domain name identified under the common name (CN) of a certificate as AsyncRAT Server.

Once again, Darktrace's Autonomous Response acted swiftly, blocking the connections to 195.26.255[.]81 throughout the observed AsyncRAT activity.

Figure 7: Darktrace's Autonomous Response actions were applied against the suspicious IP address 195.26.255[.]81.

A day later, Darktrace again alerted to further suspicious activity from the device. This time, connections to the suspicious endpoint 'kashuub[.]com' and IP address 191.96.207[.]246 via port 8041 were observed. Further analysis of port 8041 suggests it is commonly associated with ScreenConnect or Xcorpeon ASIC Carrier Ethernet Transport [8]. ScreenConnect has been observed in recent campaign’s where AsyncRAT has been utilized [9]. Additionally, one of the ASN’s observed, namely ‘ASN Oxide Group Limited’, was seen in both connections to kashuub[.]com and 185.49.126[.]50.

This could suggest a parallel between the two endpoints, indicating they might be hosting AsyncRAT C2 servers, as inferred from our previous analysis of the endpoint 185.49.126[.]50 and its association with AsyncRAT [5]. OSINT reporting suggests that the “kashuub[.]com” endpoint may be associated with ScreenConnect scam domains, further supporting the assumption that the endpoint could be a C2 server.

Darktrace’s Autonomous Response technology was once again able to support the customer here, blocking connections to “kashuub[.]com”. Ultimately, this intervention halted the compromise and prevented the attack from escalating or any sensitive data from being exfiltrated from the customer’s network into the hands of the threat actors.

Darktrace’s Autonomous Response applied a total of nine actions against the IP address 191.96.207[.]246 and the domain 'kashuub[.]com', successfully blocking the connections.
Figure 8: Darktrace’s Autonomous Response applied a total of nine actions against the IP address 191.96.207[.]246 and the domain 'kashuub[.]com', successfully blocking the connections.

Due to the popularity of this RAT, it is difficult to determine the motive behind the attack; however, from existing knowledge of what the RAT does, we can assume accessing and exfiltrating sensitive customer data may have been a factor.

Conclusion

While some cybercriminals seek stability and simplicity, openly available RATs like AsyncRAT provide the infrastructure and open the door for even the most amateur threat actors to compromise sensitive networks. As the cyber landscape continually shifts, RATs are now being used in all types of attacks.

Darktrace’s suite of AI-driven tools provides organizations with the infrastructure to achieve complete visibility and control over emerging threats within their network environment. Although AsyncRAT’s lack of concealment allowed Darktrace to quickly detect the developing threat and alert on unusual behaviors, it was ultimately Darktrace Autonomous Response's consistent blocking of suspicious connections that prevented a more disruptive attack.

Credit to Isabel Evans (Cyber Analyst), Priya Thapa (Cyber Analyst) and Ryan Traill (Analyst Content Lead)

Appendices

  • Real-time Detection Models
       
    • Compromise / Suspicious SSL Activity
    •  
    • Compromise / Beaconing Activity To      External Rare
    •  
    • Compromise / High Volume of      Connections with Beacon Score
    •  
    • Anomalous Connection / Suspicious      Self-Signed SSL
    •  
    • Compromise / Sustained SSL or HTTP      Increase
    •  
    • Compromise / SSL Beaconing to Rare      Destination
    •  
    • Compromise / Suspicious Beaconing      Behaviour
    •  
    • Compromise / Large Number of      Suspicious Failed Connections
  •  
  • Autonomous     Response Models
       
    • Antigena / Network / Significant      Anomaly / Antigena Controlled and Model Alert
    •  
    • Antigena / Network / Significant      Anomaly / Antigena Enhanced Monitoring from Client Block

List of IoCs

·     185.49.126[.]50 - IP – AsyncRAT C2 Endpoint

·     195.26.255[.]81 – IP - AsyncRAT C2 Endpoint

·      191.96.207[.]246 – IP – Likely AsyncRAT C2 Endpoint

·     CN=AsyncRAT Server - SSL certificate - AsyncRATC2 Infrastructure

·      Kashuub[.]com– Hostname – Likely AsyncRAT C2 Endpoint

MITRE ATT&CK Mapping:

Tactic –Technique – Sub-Technique  

 

Execution– T1053 - Scheduled Task/Job: Scheduled Task

DefenceEvasion – T1497 - Virtualization/Sandbox Evasion: System Checks

Discovery– T1057 – Process Discovery

Discovery– T1082 – System Information Discovery

LateralMovement - T1021.001 - Remote Services: Remote Desktop Protocol

Collection/ Credential Access – T1056 – Input Capture: Keylogging

Collection– T1125 – Video Capture

Commandand Control – T1105 - Ingress Tool Transfer

Commandand Control – T1219 - Remote Access Software

Exfiltration– T1041 - Exfiltration Over C2 Channel

 

References

[1]  https://blog.talosintelligence.com/operation-layover-how-we-tracked-attack/

[2] https://intel471.com/blog/china-cybercrime-undergrond-deepmix-tea-horse-road-great-firewall

[3] https://www.attackiq.com/2024/08/01/emulate-asyncrat/

[4] https://www.fortinet.com/blog/threat-research/spear-phishing-campaign-with-new-techniques-aimed-at-aviation-companies

[5] https://www.virustotal.com/gui/ip-address/185.49.126[.]50/community

[6] https://dfir.ch/posts/asyncrat_quasarrat/

[7] https://www.virustotal.com/gui/ip-address/195.26.255[.]81

[8] https://www.speedguide.net/port.php?port=8041

[9] https://www.esentire.com/blog/exploring-the-infection-chain-screenconnects-link-to-asyncrat-deployment

[10] https://scammer.info/t/taking-out-connectwise-sites/153479/518?page=26

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About the author
Isabel Evans
Cyber Analyst

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May 13, 2025

Revolutionizing OT Risk Prioritization with Darktrace 6.3

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Powering smarter protection for industrial systems

In industrial environments, security challenges are deeply operational. Whether you’re running a manufacturing line, a power grid, or a semiconductor fabrication facility (fab), you need to know: What risks can truly disrupt my operations, and what should I focus on first?

Teams need the right tools to shift from reactive defense, constantly putting out fires, to proactively thinking about their security posture. However, most OT teams are stuck using IT-centric tools that don’t speak the language of industrial systems, are consistently overwhelmed with static CVE lists, and offer no understanding of OT-specific protocols. The result? Compliance gaps, siloed insights, and risk models that don’t reflect real-world exposure, making risk prioritization seem like a luxury.

Darktrace / OT 6.3 was built in direct response to these challenges. Developed in close collaboration with OT operators and engineers, this release introduces powerful upgrades that deliver the context, visibility, and automation security teams need, without adding complexity. It’s everything OT defenders need to protect critical operations in one platform that understands the language of industrial systems.

additions to darktrace / ot 6/3

Contextual risk modeling with smarter Risk Scoring

Darktrace / OT 6.3 introduces major upgrades to OT Risk Management, helping teams move beyond generic CVE lists with AI-driven risk scoring and attack path modeling.

By factoring in real-world exploitability, asset criticality, and operational context, this release delivers a more accurate view of what truly puts critical systems at risk.

The platform now integrates:

  • CISA’s Known Exploited Vulnerabilities (KEV) database
  • End-of-life status for legacy OT devices
  • Firewall misconfiguration analysis
  • Incident response plan alignment

Most OT environments are flooded with vulnerability data that lacks context. CVE scores often misrepresent risk by ignoring how threats move through the environment or whether assets are even reachable. Firewalls are frequently misconfigured or undocumented, and EOL (End of Life) devices, some of the most vulnerable, often go untracked.

Legacy tools treat these inputs in isolation. Darktrace unifies them, showing teams exactly which attack paths adversaries could exploit, mapped to the MITRE ATT&CK framework, with visibility into where legacy tech increases exposure.

The result: teams can finally focus on the risks that matter most to uptime, safety, and resilience without wasting resources on noise.

Automating compliance with dynamic IEC-62443 reporting

Darktrace / OT now includes a purpose-built IEC-62443-3-3 compliance module, giving industrial teams real-time visibility into their alignment with regulatory standards. No spreadsheets required!

Industrial environments are among the most heavily regulated. However, for many OT teams, staying compliant is still a manual, time-consuming process.

Darktrace / OT introduces a dedicated IEC-62443-3-3 module designed specifically for industrial environments. Security and operations teams can now map their security posture to IEC standards in real time, directly within the platform. The module automatically gathers evidence across all four security levels, flags non-compliance, and generates structured reports to support audit preparation, all in just a few clicks.Most organizations rely on spreadsheets or static tools to track compliance, without clear visibility into which controls meet standards like IEC-62443. The result is hidden gaps, resource-heavy audits, and slow remediation cycles.

Even dedicated compliance tools are often built for IT, require complex setup, and overlook the unique devices found in OT environments. This leaves teams stuck with fragmented reporting and limited assurance that their controls are actually aligned with regulatory expectations.

By automating compliance tracking, surfacing what matters most, and being purpose built for industrial environments, Darktrace / OT empowers organizations to reduce audit fatigue, eliminate blind spots, and focus resources where they’re needed most.

Expanding protocol visibility with deep insights for specialized OT operations

Darktrace has expanded its Deep Packet Inspection (DPI) capabilities to support five industry-specific protocols, across healthcare, semiconductor manufacturing, and ABB control systems.

The new protocols build on existing capabilities across all OT industry verticals and protocol types to ensure the Darktrace Self-Learning AI TM can learn intelligently about even more assets in complex industrial environments. By enabling native, AI-driven inspection of these protocols, Darktrace can identify both security threats and operational issues without relying on additional appliances or complex integrations.

Most security platforms lack native support for industry-specific protocols, creating critical visibility gaps in customer environments like healthcare, semiconductor manufacturing, and ABB-heavy industrial automation. Without deep protocol awareness, organizations struggle to accurately identify specialized OT and IoT assets, detect malicious activity concealed within proprietary protocol traffic, and generate reliable device risk profiles due to insufficient telemetry.

These blind spots result in incomplete asset inventories, and ultimately, flawed risk posture assessments which over-index for CVE patching and legacy equipment.

By combining protocol-aware detection with full-stack visibility across IT, OT, and IoT, Darktrace’s AI can correlate anomalies across domains. For example, connecting an anomaly from a Medical IoT (MIoT) device with suspicious behavior in IT systems, providing actionable, contextual insights other solutions often miss.

Conclusion

Together, these capabilities take OT security beyond alert noise and basic CVE matching, delivering continuous compliance, protocol-aware visibility, and actionable, prioritized risk insights, all inside a single, unified platform built for the realities of industrial environments.

[related-resource]

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About the author
Pallavi Singh
Product Marketing Manager, OT Security & Compliance
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