Whether you're downloading a video from YouTube or converting a Word document into a PDF file, there's a chance that you might be unwittingly handing your personal information straight into the hands of cybercriminals.

That's the warning that has been issued by the FBI, whose Denver Field Office raised the alarm about the danger of boobytrapped file-conversion tools being used to spread malware.

For many users it's not that unusual to search the web for a free tool to convert an image file from one file format to another - such as a Word document to a PDF, a spreadsheet to a CSV, a video to a GIF, or even an MP3 audio file into a text transcript.

You may not have an "official" tool already installed to complete the conversion, so you may feel comfortable searching the web for a utility to do the job for you for free.

But how can you feel truly confident the tool you have just allowed to execute on your PC isn't doing something else behind the scenes?

According to the FBI, scams involving online file converters are infecting users' computers with malware that allows hackers to gain remote access, steal email addresses, passwords, social security numbers, cryptocurrency seed phrases and wallet details, as well as other personal information.

Marvin Massey, an assistant special agent at the FBI's Denver field office told the media that the scam has become "rampant" across the United States, and that an incident was recorded within the Denver Metro area in the last two weeks.

According to the FBI, many victims are not aware that their computers have become infected until it is too late. Their identity has been stolen, or their PC has become infected with ransomware.

Although the wording of the FBI's warning is vague, it appears to apply both to online websites that do the conversion as well as apps that users download to their computers to transform files from one format to another.

"The best way to thwart these fraudsters is to educate people so they don't fall victim to these fraudsters in the first place," said FBI Denver Special Agent in Charge Mark Michalek. "If you or someone you know has been affected by this scheme, we encourage you to make a report and take actions to protect your assets. Every day, we are working to hold these scammers accountable and provide victims with the resources they need."

The FBI's Denver Field Office is asking victims to get in touch with them if they believe they have encountered a malicious file convertor tool - presumably in an attempt to have such sites shut down, and potentially identify those responsible for the malicious campaign.