FBI Warns Free Online File Converters May Hide Malware

The FBI is warning internet users about scam websites offering free online file conversion services that secretly install malware on their devices.

The FBI Denver Field Office has reported a rise in cybercriminals using these tools to infect victims’ computers, leading to data theft, ransomware attacks, and other cyber threats.

“The best way to thwart these fraudsters is to educate people so they don’t fall victim in the first place,” said FBI Denver Special Agent in Charge Mark Michalek. He urged victims to report the scam and take steps to protect their personal and financial information.

These fraudulent converters appear legitimate, allowing users to change file formats—such as converting .doc to .pdf or merging multiple images into a single file. However, in the background, the downloaded file often contains hidden malware.

This malware can steal sensitive information, including Social Security numbers, banking details, cryptocurrency wallets, email credentials, and passwords.

Cybercriminals employ various tactics to distribute the malware. Some websites prompt users to download a tool or install a browser extension, which turns out to be adware or a browser hijacker.

In more advanced cases, the converted file itself contains malicious code that silently installs spyware or information-stealing malware.

Many victims don’t realize their devices are compromised until they experience identity theft, unauthorized transactions, or a ransomware attack. Experts from cybersecurity firm Malwarebytes have noted that, beyond ransomware, these scams can also introduce browser hijackers and other unwanted programs.

To protect against these scams, the FBI advises users to be cautious with free online converters and to keep their antivirus software updated. They also recommend scanning any downloaded file before opening it.

If you suspect you’ve been affected, the FBI urges immediate action: contact your bank, change all passwords using a secure device, and run a malware scan. Victims should report incidents to the FBI’s Internet Crime Complaint Center at www.ic3.gov.