New research by SonicWall indicates that cyber attacks involving weaponized PDFs have dramatically increased in the past months. Last year, the company detected 47,000 PDF-based attacks. However, attacks of this kind began increasing in December and surged in March when 73,000 attacks were discovered, far more than the total for the entirety of 2018. Many of the attacks originated from Russia.

Cyber criminals often hide malicious links in PDFs that direct users to cyber scams or malware. Traditional security solutions usually fail to identify malicious PDFs, even though this file type is incredibly popular. In fact, SonicWall CEO Bill Conner believes the rise of PDF-based attacks is worrisome because “our businesses and governments run on PDFs today.”

Read more: Report: Weaponized PDFs on the Rise