Google Chrome users have been warned to keep their eyes peeled for a malicious extension that can make hackers infiltrate their personal accounts and drain money from their bank.
The threat, called Cloud9, allows hackers to steal the information available during the browser session.
Security firm Zimperium says Cloud9 can also install malware on a user's device, so that hackers can then take control of a device remotely and steal someone's passwords as well as credit card data.
The extension is not available on the official Chrome web store but is spread through channels such as websites promoting fake Adobe Flash Player updates.
The dangerous extension comes from the Keksec malware group, which was originally formed in 2016.
The number of victims affected by the malware is unknown at the moment, but according to Zimperium the group is "targeting all browsers and operating systems".
Zimperium researcher Nipun Gupta said in a report : "We found some screenshots from a hacker forum where the threat actor showcases the victims they have under attack."
The report added: "The Cloud9 botnet is being sold either for free or for a few hundred dollars on various different hacker forums.
"As it is quite trivial to use and available for free, it can be used by many malware groups or individuals for specific purposes."
Google told tech website Bleeping Computer: "We always recommend users update to the latest version of Google Chrome to ensure they have the most up-to-date security protections.
"Users can also stay better protected from malicious executables and websites by enabling Enhanced Protection in the privacy and security settings in Chrome.
"Enhanced Protection automatically warns you about potentially risky sites and downloads and inspects the safety of your downloads and warns you when a file may be dangerous."