File Converter Malware: FBI Warns of Rising Ransomware Threat

The FBI Denver Field Office has warned sternly about the rising threat of malicious online file converter tools.

These seemingly harmless services, often advertised as free tools to convert or merge files, are being weaponized by cybercriminals to install malware on users’ computers.

This malware can have devastating consequences, including ransomware attacks and identity theft.

How the Scam Works

Cybercriminals exploit popular online search terms like “free PDF to DOC converter” or “merge JPG to PDF” to lure victims.

The fraudulent websites mimic legitimate services, sometimes altering URLs slightly (e.g., replacing “.com” with “.co”) or appearing as paid results in search engines.

Once a user uploads a file for conversion, the returned file may contain hidden malware.

In some cases, instead of a converted document, users unknowingly download malicious executables or JavaScript files.

These tools not only infect devices but also scrape sensitive data from uploaded files.

Information at risk includes:

• Personal Identifiable Information (PII), such as Social Security Numbers and dates of birth.
• Banking credentials and cryptocurrency wallet details.
• Login passwords and email addresses.

The Role of Malware and Ransomware

Malware embedded in these fake converters often serves as a gateway for more severe threats like ransomware.

Ransomware encrypts victims’ files, rendering them inaccessible until a ransom is paid, typically in cryptocurrencies like Bitcoin.

Advanced ransomware variants can spread across networks, targeting high-value systems and escalating damages.

For example, malicious executables like “Pdfixers.exe” or JavaScript payloads such as Gootloader have been identified as common threats distributed through these scams.

Gootloader, in particular, is notorious for downloading additional malware like banking trojans and post-exploitation tools such as Cobalt Strike beacons.

FBI Recommendations for Protection

To safeguard against these scams, the FBI Denver Field Office advises:

1. Verify URLs: Check website addresses carefully to avoid lookalike domains.
2. Avoid Sponsored Links: Be cautious of ads at the top of search results.
3. Use Antivirus Software: Keep antivirus programs updated and scan all downloaded files.
4. Research Tools: Opt for well-reviewed and established applications instead of unknown online converters.

If you suspect your device has been compromised:

• Immediately contact your financial institutions.
• Change all passwords using a secure device.
• File a report with the FBI’s Internet Crime Complaint Center at www.ic3.gov.
• Seek professional help to remove malware from your device.

Broader Implications

The FBI warns that these scams are not limited to individual users but can also target organizations.

For instance, the February ransomware attack on a media company in Davenport, Iowa, reportedly stemmed from such malicious file converters.

This highlights the potential for minor scams to escalate into major cybersecurity breaches.

Final Thoughts

Mark Michalek, Special Agent in Charge at FBI Denver, emphasized the importance of public awareness: “The best way to thwart these fraudsters is to educate people so they don’t fall victim in the first place.”

By staying vigilant and adopting best practices for online safety, users can protect their devices and sensitive information from falling into the hands of cybercriminals.

This warning underscores the evolving tactics of cybercriminals and the critical need for robust cybersecurity measures in both personal and organizational contexts.

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