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August 22, 2024

From the Depths: Analyzing the Cthulhu Stealer Malware for macOS

Cado Security (now part of Darktrace) analyzed "Cthulhu Stealer," a macOS malware-as-a-service written in Go. It impersonates legitimate software, prompts for user and MetaMask passwords, and steals credentials, cryptocurrency wallets, and game accounts. Functionally similar to Atomic Stealer, Cthulhu was rented via an underground marketplace, but its operators faced complaints and a ban for alleged exit scamming.
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
Tara Gould
Malware Research Lead
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22
Aug 2024

Introduction

For years there has been a general belief that macOS systems are immune to malware. While MacOS has a reputation for being secure, macOS malware has been trending up in recent years with the emergence of Silver Sparrow [1],  KeRanger [2], and Atomic Stealer [3], among others. Recently, Cado Security has identified a malware-as-a-service (MaaS) targeting macOS users named “Cthulhu Stealer”. This blog will explore the functionality of this malware and provide insight into how its operators carry out their activities.

Technical analysis

File details:

Language: Go

Not signed

Stripped

Multiarch: x86_64 and arm

Screenshot
Figure 1: Screenshot of disk image when mounted

Cthulhu Stealer is an Apple disk image (DMG) that is bundled with two binaries, depending on the architecture. The malware is written in GoLang and disguises itself as legitimate software. Once the user mounts the dmg, the user is prompted to open the software. After opening the file, “osascript”, the macOS command-line tool for running AppleScript and JavaScript is used to prompt the user for their password. 

Password Prompt
Figure 2: Password Prompt 
Osascript
Figure 3: Osascript prompting user for password

Once the user enters their password, a second prompt requests the user’s MetaMask [4] password. A directory is created in ‘/Users/Shared/NW’ with the credentials stored in textfiles. Chainbreak [5] is used to dump Keychain passwords and stores the details in “Keychain.txt”.

Wallet Connect Password prompt
Figure 4: Password prompt for MetaMask
Directory
Figure 5: Directory /Users/Shared/NW with created files

A zip file containing the stolen data is created in: “/Users/Shared/NW/[CountryCode]Cthulhu_Mac_OS_[date]_[time].zip.” Additionally, a notification is sent to the C2, to alert to new logs. The malware fingerprints the victim’s system, gathering information including IP, with IP details that are retrieved from ipinfo.io.  

System information including system name, OS version, hardware and software information is also gathered and stored in a text file.

Parsed IP Details
Figure 6: Parsed IP Details 
Cthulhu Stealer
Figure 7: Contents of ‘Userinfo.txt’
Code
Figure 8: Part of the function saving system information to text file
Log Alert
Figure 9: Alert of Log that is sent to operators

Cthulhu Stealer impersonates disk images of legitimate software that include:

  • CleanMyMac
  • Grand Theft Auto IV (appears to be a typo for VI)
  • Adobe GenP

The main functionality of Cthulhu Stealer is to steal credentials and cryptocurrency wallets from various stores, including game accounts. Shown in Figure 10, there are multiple checker functions that check in the installation folders of targeted file stores, typically in “Library/Application Support/[file store]”. A directory is created in “/Users/Shared/NW” and the contents of the installation folder are dumped into text files for each store.

Code
Figure 10: “Checker” functions being called in main function
Code
Figure 11: Function BattleNetChecker

A list of stores Cthulhu Stealer steals from is shown in the list below:

  • Browser Cookies
  • Coinbase Wallet
  • Chrome Extension Wallets
  • Telegram Tdata account information
  • Minecraft user information
  • Wasabi Wallet
  • MetaMask Wallet
  • Keychain Passwords
  • SafeStorage Passwords
  • Battlenet game, cache and log data
  • Firefox Cookies
  • Daedalus Wallet
  • Electrum Wallet
  • Atomic Wallet
  • Binanace Wallet
  • Harmony Wallet
  • Electrum Wallet
  • Enjin Wallet
  • Hoo Wallet
  • Dapper Wallet
  • Coinomi Wallet
  • Trust Wallet

Comparison to atomic stealer

Atomic Stealer [6] is an information-stealer that targets macOS written in Go that was first identified in 2023. Atomic Stealer steals crypto wallets, browser credentials, and keychain. The stealer is sold on Telegram to affiliates for $1,000 per month. The functionality and features of Cthulhu Stealer are very similar to Atomic Stealer, indicating the developer of Cthulhu Stealer probably took Atomic Stealer and modified the code. The use of “osascript”  to prompt the user for their password is similar in Atomic Stealer and Cthulhu, even including the same spelling mistakes. 

Forum and operators

The developers and affiliates of Cthulhu Stealer operate as “Cthulhu Team” using Telegram for communications. The stealer appears to be being rented out to individuals for $500 USD/month, with the main developer paying out a percentage of earnings to affiliates based on their deployment. Each affiliate of the stealer is responsible for the deployment of the malware. Cado has found Cthulhu Stealer sold on two well-known malware marketplaces which are used for communication, arbitration and advertising of the stealer, along with Telegram. The user “Cthulhu” (also known as Balaclavv), first started advertising Cthulhu Stealer at the end of 2023 and appeared to be operating for the first few months of 2024, based on timestamps from the binaries. 

Various affiliates of the stealer started lodging complaints against Cthulhu in 2024 with regards to payments not being received. Users complained that Cthulhu had stolen money that was owed to them and accused the threat actor of being a scammer or participating in an exit scam. As a result, the threat actor received a permanent ban from the marketplace.

Screenshot
Figure 12: Screenshot of an arbitration an affiliate lodged against Cthulhu

Key takeaways 

In conclusion, while macOS has long been considered a secure system, the existence of malware targeting Mac users remains an increasing security concern. Although Cthulhu Team no longer appears to be active, this serves as a reminder that Apple users are not immune to cyber threats. It’s crucial to remain vigilant and exercise caution, particularly when installing software from unofficial sources.

To protect yourself from potential threats, always download software from trusted sources, such as the Apple App Store or the official websites of reputable developers. Enable macOS’s built-in security features such as Gatekeeper, which helps prevent the installation of unverified apps. Keep your system and applications up to date with the latest security patches. Additionally, consider using reputable antivirus software to provide an extra layer of protection.

By staying informed and taking proactive steps, you can significantly reduce the risk of falling victim to Mac malware and ensure your system remains secure.

Indicators of compromise

Launch.dmg  

6483094f7784c424891644a85d5535688c8969666e16a194d397dc66779b0b12  

GTAIV_EarlyAccess_MACOS_Release.dmg  

e3f1e91de8af95cd56ec95737669c3512f90cecbc6696579ae2be349e30327a7  

AdobeGenP.dmg  

f79b7cbc653696af0dbd867c0a5d47698bcfc05f63b665ad48018d2610b7e97b  

Setup2024.dmg  

de33b7fb6f3d77101f81822c58540c87bd7323896913130268b9ce24f8c61e24  

CleanMyMac.dmg  

96f80fef3323e5bc0ce067cd7a93b9739174e29f786b09357125550a033b0288  

Network indicators  

89[.]208.103.185  

89[.]208.103.185:4000/autocheckbytes  

89[.]208.103.185:4000/notification_archive  

MITRE ATTACK  

User Execution  

T1204  

Command and Scripting Interpreter: Apple Script  

T1059.002  

Credentials From Password Stores  

T1555  

Credentials From Password Stores: Keychain  

T1555.001  

Credentials From Password Stores: Credentials From Web Browser  

T1555.003  

Account Discovery   

T1087  

System Information Discovery  

T1082  

Data Staged  

T1074  

Data From Local System  

T1005  

Exfiltration Over C2 Channel  

T1041  

Financial Theft  

Detection

Yara

rule MacoOS_CthulhuStealer {   
meta:       
 Description = "Detects Cthulhu MacOS Stealer Binary"       
 author = "Cado Security"       
 date = "14/08/2024"       
 md5 = "897384f9a792674b969388891653bb58" strings:           
 $mach_o_x86_64 = {CF FA ED FE 07 00 00 01 00 00 00 00 00 00 00 00}           
 $mach_o_arm64 = {CF FA ED FE 0C 00 00 01 00 00 00 00 00 00 00 00}          $c2 = "http://89.208.103.185:4000"           
 $path1 = "/Users/Shared/NW" fullword          $path2 = "/Users/admin/Desktop/adwans/Builder/6987368329/generated_script.go" fullword          $path3 = "ic.png" fullword           
 $zip = "@====)>>>>>>>>> CTHULHU STEALER - BOT <<<<<<<<<(====@\n" fullword          $func1 = "copyKeychainFile"           
 $func2 = "grabberA1"           
 $func3 = "grabberA2"          
 $func4 = "decodeIPInfo"           
 $func5 = "battlenetChecker"           
 $func6 = "binanceChecker"          
 $func7 = "daedalusChecker"           
 $func8 = "CCopyFFolderContents"           
 $func9 = "electrumChecker"         
 
condition:         
 $mach_o_x86_64 or $mach_o_arm64           
 and any of ($func*) or any of ($path*) or ($c2) or ($zip) } 

References

[1] https://redcanary.com/blog/threat-intelligence/clipping-silver-sparrows-wings/

[2] https://unit42.paloaltonetworks.com/new-os-x-ransomware-keranger-infected-transmission-bittorrent-client-installer/

[3] https://www.sentinelone.com/blog/atomic-stealer-threat-actor-spawns-second-variant-of-macos-malware-sold-on-telegram/

[4] https://metamask.io/

[5] https://github.com/n0fate/chainbreaker

[6] https://www.sentinelone.com/blog/atomic-stealer-threat-actor-spawns-second-variant-of-macos-malware-sold-on-telegram/

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
Tara Gould
Malware Research Lead

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April 2, 2026

How Chinese-Nexus Cyber Operations Have Evolved – And What It Means For Cyber Risk and Resilience 

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Cybersecurity has traditionally organized risk around incidents, breaches, campaigns, and threat groups. Those elements still matter—but if we fixate on individual incidents, we risk missing the shaping of the entire ecosystem. Nation‑state–aligned operators are increasingly using cyber operations to establish long-term strategic leverage, not just to execute isolated attacks or short‑term objectives.  

Our latest research, Crimson Echo, shifts the lens accordingly. Instead of dissecting campaigns, malware families, or actor labels as discrete events, the threat research team analyzed Chinese‑nexus activity as a continuum of behaviors over time. That broader view reveals how these operators position themselves within environments: quietly, patiently, and persistently—often preparing the ground long before any recognizable “incident” occurs.  

How Chinese-nexus cyber threats have changed over time

Chinese-nexus cyber activity has evolved in four phases over the past two decades. This ranges from early, high-volume operations in the 1990s and early 2000s to more structured, strategically-aligned activity in the 2010s, and now toward highly adaptive, identity-centric intrusions.  

Today’s phase is defined by scale, operational restraint, and persistence. Attackers are establishing access, evaluating its strategic value, and maintaining it over time. This reflects a broader shift: cyber operations are increasingly integrated into long-term economic and geopolitical strategies. Access to digital environments, specifically those tied to critical national infrastructure, supply chains, and advanced technology, has become a form of strategic leverage for the long-term.  

How Darktrace analysts took a behavioral approach to a complex problem

One of the challenges in analyzing nation-state cyber activity is attribution. Traditional approaches often rely on tracking specific threat groups, malware families, or infrastructure. But these change constantly, and in the case of Chinese-nexus operations, they often overlap.

Crimson Echo is the result of a retrospective analysis of three years of anomalous activity observed across the Darktrace fleet between July 2022 and September 2025. Using behavioral detection, threat hunting, open-source intelligence, and a structured attribution framework (the Darktrace Cybersecurity Attribution Framework), the team identified dozens of medium- to high-confidence cases and analyzed them for recurring operational patterns.  

This long-horizon, behavior-centric approach allows Darktrace to identify consistent patterns in how intrusions unfold, reinforcing that behavioral patterns that matter.  

What the data shows

Several clear trends emerged from the analysis:

  • Targeting is concentrated in strategically important sectors. Across the dataset, 88% of intrusions occurred in organizations classified as critical infrastructure, including transportation, critical manufacturing, telecommunications, government, healthcare, and Information Technology (IT) services.  
  • Strategically important Western economies are a primary focus. The US alone accounted for 22.5% of observed cases, and when combined with major European economies including Germany, Italy, Spain and the UK, over half of all intrusions (55%) were concentrated in these regions.  
  • Nearly 63% of intrusions of intrusions began with the exploitation of internet-facing systems, reinforcing the continued risk posed by externally exposed infrastructure.  

Two models of cyber operations

Across the dataset, Chinese-nexus activity followed two operational models.  

The first is best described as “smash and grab.” These are short-horizon intrusions optimized for speed. Attackers move quickly – often exfiltrating data within 48 hours – and prioritize scale over stealth. The median duration of these compromises is around 10 days. It’s clear they are willing to risk detection for short-term gain.  

The second is “low and slow.” These operations were less prevalent in the dataset, but potentially more consequential. Here, attackers prioritize persistence, establishing durable access through identity systems and legitimate administrative tools, so they can maintain access undetected for months or even years. In one notable case, the actor had fully compromised the environment and established persistence, only to resurface in the environment more than 600 days after. The operational pause underscores both the depth of the intrusion and the actor’s long‑term strategic intent. This suggests that cyber access is a strategic asset to preserve and leverage over time, and we observed these attacks most often inin sectors of the high strategic importance.  

It’s important to note that the same operational ecosystem can employ both models concurrently, selecting the appropriate model based on target value, urgency, intended access. The observation of a “smash and grab” model should not be solely interpreted as a failure of tradecraft, but instead an operational choice likely aligned with objectives. Where “low and slow” operations are optimized for patience, smash and grab is optimized for speed; both seemingly are deliberate operational choices, not necessarily indicators of capability.  

Rethinking cyber risk

For many organizations, cyber risk is still framed as a series of discrete events. Something happens, it is detected and contained, and the organization moves on. But persistent access, particularly in deeply interconnected environments that span cloud, identity-based SaaS and agentic systems, and complex supply chain networks, creates a major ongoing exposure risk. Even in the absence of disruption or data theft, that access can provide insight into operations, dependencies, and strategic decision-making. Cyber risk increasingly resembles long-term competitive intelligence.  

This has impact beyond the Security Operations Center. Organizations need to shift how they think about governance, visibility, and resilience, and treat cyber exposure as a structural business risk instead of an incident response challenge.  

What comes next

The goal of this research is to provide a clearer understanding of how these operations work, so defenders can recognize them earlier and respond more effectively. That includes shifting from tracking indicators to understanding behaviors, treating identity providers as critical infrastructure risks, expanding supplier oversight, investing in rapid containment capabilities, and more.  

Learn more about the findings of Darktrace’s latest research, Crimson Echo: Understanding Chinese-nexus Cyber Operations Through Behavioral Analysis, by downloading the full report and summaries for business leaders, CISOs, and SOC analysts here.  

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Nathaniel Jones
VP, Security & AI Strategy, Field CISO

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April 1, 2026

AI-powered security for a rapidly growing grocery enterprise

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Protecting a complex, fast-growing retail organization

For this multi-banner grocery holding organization, cybersecurity is considered an essential business enabler, protecting operations, growth, and customer trust. The organization’s lean IT team manages a highly distributed environment spanning corporate offices, 100+ stores, distribution centers and  thousands of endpoints, users, and third-party connections.

Mergers and acquisitions fueled rapid growth, but they also introduced escalating complexity that constrained visibility into users, endpoints, and security risks inherited across acquired environments.

Closing critical visibility gaps with limited resources

Enterprise-wide visibility is a top priority for the organization, says the  Vice President of Information Technology. “We needed insights beyond the perimeter into how users and devices were behaving across the organization.”

A security breach that occurred before the current IT leadership joined the company reinforced the urgency and elevated cybersecurity to an executive-level priority with a focus on protecting customer trust. The goal was to build a multi-layered security model that could deliver autonomous, enterprise-wide protection without adding headcount.

Managing cyber risk in M&A

Mergers and acquisitions are central to the grocery holding company’s growth strategy. But each transaction introduces new cyber risk, including inherited network architectures, inconsistent tooling, excessive privileges, and remnants of prior security incidents that were never fully remediated.

“Our M&A targets range from small chains with a single IT person and limited cyber tools to large chains with more developed IT teams, toolsets and instrumentation,” explains the VP of IT. “We needed a fast, repeatable, and reliable way to assess cyber risk before transactions closed.”

AI-driven security built for scale, speed, and resilience

Rather than layering additional point tools onto an already complex environment, the retailer adopted the Darktrace ActiveAI Security Platform™ in 2020 as part of a broader modernization effort to improve resilience, close visibility gaps, and establish a security foundation that could scale with growth.

“Darktrace’s AI-driven approach provided the ideal solution to these challenges,” shares the VP of IT. “It has empowered our organization to maintain a robust security strategy, ensuring the protection of our network and the smooth operation of our business.”

Enterprise-wide visibility into traffic  

By monitoring both north-south and east-west traffic and applying Self-Learning AI, Darktrace develops a dynamic understanding of how users and devices normally behave across locations, roles, and systems.

“Modeling normal behavior across the environment enables us to quickly spot behavior that doesn’t fit. Even subtle changes that could signal a threat but appear legitimate at first glance,” explains the VP of IT.

Real-time threat containment, 24/7

Adopting autonomous response has created operational breathing room for the security team, says the company’s Cybersecurity  Engineer.

“Early on, we enabled full Darktrace autonomous mode and we continue to do so today,” shares the IT Security Architect. “Allowing the technology to act first gives us the time we need to investigate incidents during business hours without putting the business at risk.”

Unified, actionable view of security ecosystem

The grocery retailer integrated Darktrace with its existing security ecosystem of firewalls, vulnerability management tools, and endpoint detection and response, and the VP of IT described the adoption process as “exceptionally smooth.”

The team can correlate enterprise-wide security data for a unified and actionable picture of all activity and risk. Using this “single pane of glass” approach, the retailer trains Level 1 and Level 2 operations staff to assist with investigations and user follow-ups, effectively extending the reach of the security function without expanding headcount.

From reactive defense to security at scale

With Darktrace delivering continuous visibility, autonomous containment, and integrated security workflows, the organization has strengthened its cybersecurity posture while improving operational efficiency. The result is a security model that not only reduces risk, but also supports growth, resilience, and informed decision-making at the business level.

Faster detection, faster resolution

With autonomous detection and response, the retailer can immediately contain risk while analysts investigate and validate activity. With this approach, the company can maintain continuous protection even outside business hours and reduce the chance of lateral spread across systems or locations.

Enterprise-grade protection with a lean team

From cloud environments to clients to SaaS collaboration tools, Darktrace provides holistic autonomous AI defense, processing petabytes of the organization’s network traffic and investigating millions of individual events that could be indicative of a wider incident.

Today, Darktrace autonomously conducts the majority of all investigations on behalf of the IT team, escalating only a tiny fraction for analyst review. The impact has been profound, freeing analysts from endless alerts and hours of triage so they can focus on more valuable, proactive, and gratifying work.

“From an operational perspective, Darktrace gives us time back,” says the Cybersecurity Engineer. More importantly, says the VP of IT, “it gives us peace of mind that we’re protected even if we’re not actively monitoring every alert.”

A strategic input for M&A decision-making

One of the most strategic outcomes has been the role of cybersecurity on M&A. 90 days prior to closing a transaction, the security team uses Darktrace alongside other tools to perform a cyber risk assessment of the potential acquisition. “Our approach with Darktrace has consistently identified gaps and exposed risks,” says the VP of IT, including:

  • Remnants of previous incidents that were never fully remediated
  • Network configurations with direct internet exposure
  • Excessive administrative privileges in Active Directory or on critical hosts

While security findings may not alter deal timelines, the VP of IT says they can have enormous business implications. “With early visibility into these risks, we can reduce exposure to inherited cyber threats, strengthen our position during negotiations, and establish clear remediation requirements.”

A security strategy built to evolve with the business

As the holding group expands its cloud footprint, it will extend Darktrace protections into Azure, applying the same AI-driven visibility and autonomous response to cloud workloads. The VP of IT says Darktrace's evolving capabilities will be instrumental in addressing the organization’s future cybersecurity needs and ability to adapt to the dynamic nature of cloud security.

“With Darktrace’s AI-driven approach, we have moved beyond reactive defense, establishing a resilient security foundation for confident expansion and modernization.”

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