FBI Warnings About Fake File Converters: A Growing Malware Threat

Online File Converters: A Useful Service? Or a Hidden Danger?

Have you ever used an online file converter? Perhaps you turned an image or word document into a pdf, or converted one image file type to another. It's a very useful service utilized by millions of people daily. Unfortunately, as with all things cyber-related - if it's a widely used service or tool it is also a prime target for cybercriminals.

The Federal Bureau of Investigation (FBI) is alerting everyone to a new and insidious cyber threat: bogus “free” online file converters that secretly push malware onto users’ devices. According to an official statement from the FBI Denver Field Office, the converted files you download may include hidden malware, allowing hackers to steal data or even deploy ransomware. This threat is particularly hard to detect, as the file converters often seem to work as advertised, providing the converted files while hiding the malware lurking within.

Fake File Converter Websites: What’s Happening?

In a recent article by Lawrence Abrams on BleepingComputer, cybersecurity experts highlighted how criminals are:

• Setting up fake websites that claim to convert or combine files.
• Sneaking malware into the “converted” or “combined” files that users then download.
• Harvesting private information (e.g., passwords, banking details, cryptocurrency wallets) directly from the uploaded files or through hidden malware.
• Exploiting vulnerabilities on victim devices to deliver ransomware or other malicious payloads.

According to the FBI, this scam can lead to full-scale ransomware attacks—and users may not realize their devices are compromised until it’s too late.

How the File Converter Scam Works

Search Engine Ads & Spoofed URLs

Cybercriminals often buy ads on popular search engines. Unsuspecting users searching for “free file converter” or “doc to pdf converter” may click on these ads, which lead to malicious download sites.

Malicious File Download

These tools usually do convert or merge the file as promised, making it very hard to detect the threat. But the resulting download could be an .exe or .js file disguised as a document. If opened, the file might grant hackers remote access to a victim’s system. Executable (.exe) and Javascript (.js) files can run code on a computer, and are often used to install malware.

Data Theft & Ransomware

Once installed, malware can scrape sensitive data from a user’s computer, including passwords, banking info, or even cryptocurrency keys. Worse, hackers can use the foothold to spread ransomware, locking an entire system or network until a hefty ransom is paid.

Details of the Official FBI Warning

In its statement, the FBI Denver Field Office warned:

“In this scenario, criminals use free online document converter tools to load malware onto victims’ computers, leading to incidents such as ransomware. […] The best way to thwart these fraudsters is to educate people so they don’t fall victim to these fraudsters in the first place.”

They advise individuals who think they may have been affected to immediately:

• Report the incident via IC3.gov.
• Update or run antivirus software.
• Notify financial institutions if there is any suspicion of compromised banking data.
• Change passwords from a trusted, secure device.

Protect Yourself: Key Steps to Avoid Fake File Converters

1. Verify Before You Convert 

• Stick to reputable websites or official software when converting or merging documents.
• Check online reviews or use known, trustworthy services. Examples of these could be Adobe’s online PDF tools, or dedicated software.

2. Always Scan Downloads

• Even if you trust the site, scan the resulting file with up-to-date antivirus software before opening.
• Legitimate file converters typically do not generate .exe or .js files.

3. Red Flags

• Look-Alike Domains: Scammers try to ape legitimate file conversion websites by using nearly identical URLs—sometimes changing just a single letter or using a different top-level domain (TLD), such as .co or .net instead of .com.
• Suspicious File Types: Watch for download prompts that don’t match the file type you expect. If you wanted a .pdf but got an .exe or .js file, there’s likely something malicious at play.

4. Maintain Good Security Hygiene 

• Keep your operating system and security software updated.
• Use unique, complex passwords, especially for email and financial accounts.

5. React to Suspicious Activity 

• If you suspect you downloaded malware, immediately disconnect from the internet and run a virus scan.
• Consider taking your computer to a professional if you suspect you’ve been compromised or you’re unsure how to remove the infection.

Don’t Lower Your Guard When Using Mobile Devices

It is also important to remember that mobile devices are also at risk. These scams can also happen on mobile devices, through malicious apps, or through malicious websites accessed on the mobile device’s web browser. It is very important to follow the same security procedures on mobile devices as on desktop computers.

The Best Defense Against Phony Websites

Fake file converters and free downloading tools may seem convenient, but many come with potentially devastating hidden risks. Protect yourself by:

• Being cautious and verifying the legitimacy of services before using them.
• Avoid clicking on “Sponsored” websites or ads, navigate directly to trusted sites.
• Scan files for potential malware before you open or share them.
• Scrutinize file types and URLs 

By following these simple steps, you can help protect yourself against malware and ransomware attacks. Want to do more? Spread awareness by sharing this post on social media and with your email contacts. Remember, it’s great to protect yourself, but it’s even better when we work together to protect the community. 

Think your computer has already been compromised? Contact us for expert assistance!