(Credit: Malwarebytes, redaction Download.com)

Fake tech support scams are a big business these days. Just about everyone we know has gotten a phone call at one point from a stranger claiming to be from Microsoft tech support, offering to fix something wrong with your computer, for a fee.

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The most successful of these scams is the type that creates the problem to begin with--and hackers have recently perfected a misuse of the file download feature in the Google Chrome browser to lock up the application window and present you with a fake tech support number to call, as reported by Ars Technica.

The hack works by exploiting behaviors in window.navigator.msSaveOrOpenBlob API (application programming interface), which is supposed to be used to present you with the option to save or download a file that you've clicked on in a web browser. The hackers have figured out a way to force this download to repeat itself very rapidly, which brings the browser to a crawl after about 10 seconds.

Antivirus company Malwarebytes reported this issue in February 2018, and it was believed to have been fixed in Chrome 65. However, some users of Chrome 67 (the current version) have said that they are still experiencing this problem, and it may also be present in Mozilla Firefox.

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If this browser lockup hack happens to you, you can try using the Windows Task Manager to force the browser window to close. Press Ctrl+Shift+Esc to open the Task Manager, click on the Applications tab, click on the browser window listed there, and click on the End Task button to kill it. You can also try the Alt+F4 keyboard shortcut to force-close an application window.

The takeaways

  1. An flaw in Chrome can be exploited by hackers to make your browser freeze up and present a face message to call Microsoft tech support. Do not call the number listed in the pop-up warning. Microsoft's official number for customer support in the United States is 1-877-696-7786, and this Microsoft webpage lists the support numbers for dozens of other countries.
  2. This hack appears to be packaged inside advertisements on disreputable websites; as always, staying out of the rougher neighborhoods of the internet can protect you against a variety of attacks.

Also see

Tom is the senior editor covering Windows at Download.com.