Financial institutions must follow specific IT security compliance standards, which regularly change. One credit union turned to Darktrace to align with its approach to compliance and risk, benefitting from email protection and proactive attack surface management.
As the Director of ITIS for a credit union in the American Pacific Northwest, I know that if malware breaches our internal systems, it will debilitate us and affect the financial wellbeing of our 10,000 members.
My security team must protect our cyber infrastructure, including our online banking, internal network, and employee email systems. As part of that effort, we are tasked heavily by the Credit Union National Association (CUNA) and the federal government to follow specific, regularly changing standards for our IT security.
To meet those compliance standards, we deployed Darktrace. Once its AI learned our digital landscape, we could customize the settings to react in specific ways that adhere to compliance frameworks, and we can easily adapt to all changes that we’ve seen.
Darktrace learns the usual behavior of every device and user within our digital landscape. It then uses this understanding to identify threats within seconds and make autonomous, precise decisions that neutralize attacks without disrupting our operations.
Since we have five locations with hundreds of computers, servers, and switches, I don’t have the capacity to watch every system. However, using network mapping and traffic moderating capabilities, Darktrace gathers all the information I could need. It then generates clear, detailed reports through Explainable AI.
With its autonomous capabilities, Darktrace helps us stay compliant and stop attacks faster and more reliably than humans, saving my team both time and money.
Stopping Email Threats with Nuanced Interventions
In my experience, most breaches happen through email. I can control most web traffic with firewall rules and third-party tools. I can’t control, however, if a user clicks on something in a malicious email.
Darktrace/Email uses AI to identify and stop malicious email activity before it ever reaches a user’s inbox. It can take more detailed actions beyond merely allowing or blocking emails. Instead, it will neutralize the threatening components of emails. I especially love its ability to flatten any attachment into a PDF.
Since deploying Darktrace, I haven’t had a security breach that I couldn’t explain or fix. Darktrace has even blocked malicious emails that made it through my outside spam folder and internal exchange filter.
The metrics it provides internally are amazing, too. I can tell who’s moving files, where they’re moving files, what files they’re moving, if they are plain text passwords or shares or other sensitive information. At a glance, Darktrace does everything that would take me hours to trace down.
With this comprehensive visibility, we’ve started using Darktrace/Email in some unique ways. For example, we pull Darktrace’s metric breakdown of email traffic and feed it into a datamining program to see the efficacy of our marketing email campaigns.
Beyond the metrics, Darktrace’s ability to autonomously respond to threats gives me peace of mind. I have a machine that watches our email and network around the clock. Beyond stopping breaches from originating in our email systems and shutting down malicious activity in our network, Darktrace brings our email and network data together to make its AI even smarter. I know that when we fall victim to a cyber-attack, Darktrace will handle it.
Preempting Attacks by Understanding Our External Footprint
External footprint monitoring is an integral part of internal security because detecting and stopping an attack once it is launched is one thing, but being able to preempt an attack is even better. That’s why I deployed Darktrace PREVENT/Attack Surface Management™ (ASM) as soon as I could. It enables me to take a proactive approach and minimize risk before an attack ever occurs.
PREVENT/ASM generates objective reports based entirely on my unique footprint. It took only 10 days from its implementation until it identified all the assets that were out there, including some we weren’t aware of.
Now, two months later, it continues to monitor our ever-changing attack surface, informing us of vulnerabilities such as shadow IT, misconfigurations, and brand abuse. When it identifies threats, it generates digestible reports that I pass along to our third-party contractor to handle.
However, PREVENT’s power is amplified when paired with Darktrace DETECT™ and Darktrace RESPOND™. These three tools work together in the Cyber AI Loop™ to harden our entire security stack.
Since PREVENT can see potential avenues of attack in advance, the Loop can leverage this data to increase sensitivity in DETECT and RESPOND around these critical access points and inform my security team where to prioritize our resources to have the highest impact.
It’s hard to choose which capability of Darktrace has helped my team the most, because with the feedback loop, I now think of it holistically. Darktrace simply provides the value that I’m paying for, and I’m glad that I have it. As far as security software goes, it’s probably the slickest piece of software I’ve seen in my life, and I’ve been doing this for 30 years.
My advice to other financial institutions is that if you don’t have an AI security system, you need it. Threat actors have started using AI in their attacks, so we need to use AI to protect against them. Otherwise, it’s like fighting a jet plane with a rock and a stick. With this proactive approach, especially with PREVENT, Darktrace is working all the time to protect our digital estate, harden our security posture, and meet our compliance standards.
Darktrace’s free Proof of Value gives you the opportunity to speak directly with a Darktrace customer in a 1-1 reference call. Start a trial today.
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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.
What are new entry points cyber attackers are using?
While traditional phishing attacks are very common for attackers, they are not the only method threat actors are using to initiate malware delivery and other malicious campaigns of cyber disruption.
For its End of Year Threat Report, Darktrace analyzed attacks targeting customer environments. While email remains the most common means of attempted initial compromise, the second half of 2023 saw a significant rise in alternative initial access methods.
Much of this is taking advantage of cloud-base applications and collaboration tools including Dropbox, Microsoft Teams, and SharePoint which have become fundamental to how organizations operate in the era of hybrid work.
DarkGate exploits Microsoft Teams
Darktrace analysts have seen threat actors attempting to infect target networks with malware by leveraging Microsoft Teams and SharePoint.
In one example, Darktrace detected an attacker delivering DarkGate a trojan used to download other malware, by sending messages and attachments in Microsoft Teams and SharePoint.
The External Access functionality in Microsoft Teams allows users to contact people who aren’t in their organization. It’s designed as a tool to aid collaboration, but threat actors have realized they can abuse it for their own gain.
Users are told to lookout for suspicious email phishing messages, but often this thinking isn’t applied to Microsoft Teams and other collaboration platforms.
Messages from outside the organization are marked with a note that they are coming from an external source, but a well-designed phishing message with an urgent call to action can persuade the target to ignore this, driving them towards an external SharePoint URL, which tricks the user into downloading and installing malware.
Because this happens outside of the inbox, the activity can be missed by traditional email security solutions. Fortunately, in this case, it was detected by Darktrace DETECT and the activity was contained by Darktrace RESPOND before it could drop any additional malware.
Dropbox has established itself as a leading cloud storage service by allowing users to share and access files, no matter where they are in the world or what device they’re using. But while this is legitimate and useful for organizations, it has also opened a new avenue for threat actors to exploit.
Dropbox as an attack vector
Darktrace recently detected attackers attempting to leverage Dropbox as an initial access method. Emails from ‘no-reply@dropbox[.]com’ – a legitimate email address – were sent to employees at a Darktrace customer.
The emails contained a link to push users towards to a PDF file hosted on Dropbox, which in turn contained a phishing link which if followed, took users to a convincing looking spoof of a Microsoft 365 login page designed to steal usernames and passwords.
A user fell victim to this campaign, unwittingly entering their Microsoft 365 credentials. Shortly after that, Darktrace/Apps started to see suspicious activity relating to the account, with multiple logins from unusual locations which had never been associated with the account previously.
While many traditional security solutions successfully detect and disrupt email-based attacks, many struggle with cloud-based apps and services like Dropbox, Microsoft 365 and others.
There are several reasons for this, including the way in which the use of multiple different cloud services fragments the attack surface, making it hard for network administrators to keep track of everything, alongside the way in which some security solutions don’t take behavior into account in a system which can be accessed from anywhere. That means even from the other side of the world, attackers who have the right cloud credentials could access the network, potentially without being disrupted.
Why are attackers turning to alternative access methods?
Attackers are turning to alternative methods because delivering malicious links and payloads via cloud-based services potentially bypasses traditional cybersecurity protections. That, combined with how attackers can take legitimate login credentials to access system means attackers actions can’t be easily traced.
This rise in alternative initial access methods is likely a result of the continued development and enhancement of traditional email security solutions. But in the cat and mouse game of cybersecurity, threat actors continue to evolve new techniques to get by defenses.
Darktrace’s Self-Learning AI learns the unique digital environment and patterns of each business, meaning it can recognize subtle deviations in activity, even within cloud services, helping to mitigate and neutralize attacks and helping to keep your organization safe from cyber disruption.
A Thorn in Attackers’ Sides: How Darktrace Uncovered a CACTUS Ransomware Infection
24
Apr 2024
What is CACTUS Ransomware?
In May 2023, Kroll Cyber Threat Intelligence Analysts identified CACTUS as a new ransomware strain that had been actively targeting large commercial organizations since March 2023 [1]. CACTUS ransomware gets its name from the filename of the ransom note, “cAcTuS.readme.txt”. Encrypted files are appended with the extension “.cts”, followed by a number which varies between attacks, e.g. “.cts1” and “.cts2”.
As the cyber threat landscape adapts to ever-present fast-paced technological change, ransomware affiliates are employing progressively sophisticated techniques to enter networks, evade detection and achieve their nefarious goals.
How does CACTUS Ransomware work?
In the case of CACTUS, threat actors have been seen gaining initial network access by exploiting Virtual Private Network (VPN) services. Once inside the network, they may conduct internal scanning using tools like SoftPerfect Network Scanner, and PowerShell commands to enumerate endpoints, identify user accounts, and ping remote endpoints. Persistence is maintained by the deployment of various remote access methods, including legitimate remote access tools like Splashtop, AnyDesk, and SuperOps RMM in order to evade detection, along with malicious tools like Cobalt Strike and Chisel. Such tools, as well as custom scripts like TotalExec, have been used to disable security software to distribute the ransomware binary. CACTUS ransomware is unique in that it adopts a double-extortion tactic, stealing data from target networks and then encrypting it on compromised systems [2].
At the end of November 2023, cybersecurity firm Arctic Wolf reported instances of CACTUS attacks exploiting vulnerabilities on the Windows version of the business analytics platform Qlik, specifically CVE-2023-41266, CVE-2023-41265, and CVE-2023-48365, to gain initial access to target networks [3]. The vulnerability tracked as CVE-2023-41266 can be exploited to generate anonymous sessions and perform HTTP requests to unauthorized endpoints, whilst CVE-2023-41265 does not require authentication and can be leveraged to elevate privileges and execute HTTP requests on the backend server that hosts the application [2].
Darktrace’s Coverage of CACTUS Ransomware
In November 2023, Darktrace observed malicious actors leveraging the aforementioned method of exploiting Qlik to gain access to the network of a customer in the US, more than a week before the vulnerability was reported by external researchers.
Here, Qlik vulnerabilities were successfully exploited, and a malicious executable (.exe) was detonated on the network, which was followed by network scanning and failed Kerberos login attempts. The attack culminated in the encryption of numerous files with extensions such as “.cts1”, and SMB writes of the ransom note “cAcTuS.readme.txt” to multiple internal devices, all of which was promptly identified by Darktrace DETECT™.
While traditional rules and signature-based detection tools may struggle to identify the malicious use of a legitimate business platform like Qlik, Darktrace’s Self-Learning AI was able to confidently identify anomalous use of the tool in a CACTUS ransomware attack by examining the rarity of the offending device’s surrounding activity and comparing it to the learned behavior of the device and its peers.
Unfortunately for the customer in this case, Darktrace RESPOND™ was not enabled in autonomous response mode during their encounter with CACTUS ransomware meaning that attackers were able to successfully escalate their attack to the point of ransomware detonation and file encryption. Had RESPOND been configured to autonomously act on any unusual activity, Darktrace could have prevented the attack from progressing, stopping the download of any harmful files, or the encryption of legitimate ones.
Cactus Ransomware Attack Overview
Holiday periods have increasingly become one of the favoured times for malicious actors to launch their attacks, as they can take advantage of the festive downtime of organizations and their security teams, and the typically more relaxed mindset of employees during this period [4].
Following this trend, in late November 2023, Darktrace began detecting anomalous connections on the network of a customer in the US, which presented multiple indicators of compromise (IoCs) and tactics, techniques and procedures (TTPs) associated with CACTUS ransomware. The threat actors in this case set their attack in motion by exploiting the Qlik vulnerabilities on one of the customer’s critical servers.
Darktrace observed the server device making beaconing connections to the endpoint “zohoservice[.]net” (IP address: 45.61.147.176) over the course of three days. This endpoint is known to host a malicious payload, namely a .zip file containing the command line connection tool PuttyLink [5].
Darktrace’s Cyber AI Analyst was able to autonomously identify over 1,000 beaconing connections taking place on the customer’s network and group them together, in this case joining the dots in an ongoing ransomware attack. AI Analyst recognized that these repeated connections to highly suspicious locations were indicative of malicious command-and-control (C2) activity.
Figure 1: Cyber AI Analyst Incident Log showing the offending device making over 1,000 connections to the suspicious hostname “zohoservice[.]net” over port 8383, within a specific period.
The infected device was then observed downloading the file “putty.zip” over a HTTP connection using a PowerShell user agent. Despite being labelled as a .zip file, Darktrace’s detection capabilities were able to identify this as a masqueraded PuttyLink executable file. This activity resulted in multiple Darktrace DETECT models being triggered. These models are designed to look for suspicious file downloads from endpoints not usually visited by devices on the network, and files whose types are masqueraded, as well as the anomalous use of PowerShell. This behavior resembled previously observed activity with regards to the exploitation of Qlik Sense as an intrusion technique prior to the deployment of CACTUS ransomware [5].
Figure 2: The downloaded file’s URI highlighting that the file type (.exe) does not match the file's extension (.zip). Information about the observed PowerShell user agent is also featured.
Following the download of the masqueraded file, Darktrace observed the initial infected device engaging in unusual network scanning activity over the SMB, RDP and LDAP protocols. During this activity, the credential, “service_qlik” was observed, further indicating that Qlik was exploited by threat actors attempting to evade detection. Connections to other internal devices were made as part of this scanning activity as the attackers attempted to move laterally across the network.
Figure 3: Numerous failed connections from the affected server to multiple other internal devices over port 445, indicating SMB scanning activity.
The compromised server was then seen initiating multiple sessions over the RDP protocol to another device on the customer’s network, namely an internal DNS server. External researchers had previously observed this technique in CACTUS ransomware attacks where an RDP tunnel was established via Plink [5].
A few days later, on November 24, Darktrace identified over 20,000 failed Kerberos authentication attempts for the username “service_qlik” being made to the internal DNS server, clearly representing a brute-force login attack. There is currently a lack of open-source intelligence (OSINT) material definitively listing Kerberos login failures as part of a CACTUS ransomware attack that exploits the Qlik vulnerabilities. This highlights Darktrace’s ability to identify ongoing threats amongst unusual network activity without relying on existing threat intelligence, emphasizing its advantage over traditional security detection tools.
Figure 4: Kerberos login failures being carried out by the initial infected device. The destination device detected was an internal DNS server.
In the month following these failed Kerberos login attempts, between November 26 and December 22, Darktrace observed multiple internal devices encrypting files within the customer’s environment with the extensions “.cts1” and “.cts7”. Devices were also seen writing ransom notes with the file name “cAcTuS.readme.txt” to two additional internal devices, as well as files likely associated with Qlik, such as “QlikSense.pdf”. This activity detected by Darktrace confirmed the presence of a CACTUS ransomware infection that was spreading across the customer’s network.
Figure 5: The model, 'Ransom or Offensive Words Written to SMB', triggered in response to SMB file writes of the ransom note, ‘cAcTuS.readme.txt’, that was observed on the customer’s network.
Figure 6: CACTUS ransomware extensions, “.cts1” and “.cts7”, being appended to files on the customer’s network.
Following this initial encryption activity, two affected devices were observed attempting to remove evidence of this activity by deleting the encrypted files.
Figure 7: Attackers attempting to remove evidence of their activity by deleting files with appendage “.cts1”.
Conclusion
In the face of this CACTUS ransomware attack, Darktrace’s anomaly-based approach to threat detection enabled it to quickly identify multiple stages of the cyber kill chain occurring in the customer’s environment. These stages ranged from ‘initial access’ by exploiting Qlik vulnerabilities, which Darktrace was able to detect before the method had been reported by external researchers, to ‘actions on objectives’ by encrypting files. Darktrace’s Self-Learning AI was also able to detect a previously unreported stage of the attack: multiple Kerberos brute force login attempts.
If Darktrace’s autonomous response capability, RESPOND, had been active and enabled in autonomous response mode at the time of this attack, it would have been able to take swift mitigative action to shut down such suspicious activity as soon as it was identified by DETECT, effectively containing the ransomware attack at the earliest possible stage.
Learning a network’s ‘normal’ to identify deviations from established patterns of behaviour enables Darktrace’s identify a potential compromise, even one that uses common and often legitimately used administrative tools. This allows Darktrace to stay one step ahead of the increasingly sophisticated TTPs used by ransomware actors.
Credit to Tiana Kelly, Cyber Analyst & Analyst Team Lead, Anna Gilbertson, Cyber Analyst
![Cyber AI Analyst Incident Log showing the offending device making over 1,000 connections to the suspicious hostname “zohoservice[.]net” over port 8383, within a specific period.](https://assets-global.website-files.com/626ff4d25aca2edf4325ff97/662971c1cf09890fd46729a1_Screenshot%202024-04-24%20at%201.55.10%20PM.png)
