Claude, Anthropic’s AI, is becoming more and more popular. According to some estimates, it reached 290 million monthly visits. This has made the model a very attractive target for cybercriminals. Security researchers from Malwarebytes have identified a counterfeit website that closely imitates the official Claude portal and which promises to install a seemingly legitimate version of the application, with the aim of distributing an installation package infected with malware. Anyone who downloads the file actually receives a working copy of the application, but in parallel a chain of malicious components is installed that allows hackers to remotely access the device. In the next paragraphs we will therefore see how the attack works and how to avoid it.
How Claude Pro’s attack works
The fraudulent site presents itself as a web page apparently belonging to Anthropic, the company that develops Claude, and which promises to download a “Pro” version of Claude, enclosed in the Claude-Pro-windows-x64.zip file. DNS records – the system that associates domain names with IP addresses – show that the domain has an active infrastructure for sending mass emails, suggesting that the attack is also propagated via phishing messages. Once extracted, the archive contains an installer that is located in the path C:Program Files (x86)AnthropicClaudeCluade. Notice anything strange? There is a typo in the path (“Clwowde” instead of “Claude”), which represents a first warning sign.
The installation creates a shortcut on the desktop which, upon first click, starts an automatic script. This script runs the legitimate, working Claude application in the foreground, so as not to arouse suspicion, and simultaneously copies three files in the background to a system startup folder: NOVUpdate.exe, avk.dll, and NOVUpdate.exe.dat.
The mechanism underlying the attack is deliberately difficult to unmask: the malware relies on completely legitimate software components – in this specific case, elements attributable to an antivirus program – to camouflage itself within the system and escape the automatic checks of Windows. Neither the user nor the PC security tools therefore have immediate reasons to become suspicious.
In light of these considerations, it seems clear what the objective of the cyber criminals behind the attack is: to open a permanent access door to the victim’s device without them realizing it. In this way, whoever manages the attack can issue commands remotely, steal sensitive information or have the system download additional malicious components without anything being visible on the screen.
How to tell if your PC is infected
To check if your computer was involved in the attack, in addition to thinking about it and trying to remember if you have downloaded “strange” versions of Claude on your PC, you can check the presence of NOVUpdate.exe, avk.dll or NOVUpdate.exe.dat files in the Startup autostart folder, look for the folder with the incorrect name “Cluade” in the path C:Program Files (x86)AnthropicClaude and run a full scan with an updated anti-malware. If successful, the researchers of Malwarebytes suggest immediately disconnecting from the Internet and changing the passwords of all accounts used on that device.
Preventing the infection is much simpler than eradicating it: just download Claude exclusively from the platform’s official website, avoiding links from emails, advertisements or sponsored results in search engines. And this defense strategy obviously applies to any other software.
