UNC3753 Used Vishing and Physical Intrusions in U.S. Data Theft Extortion Campaign

Cybersecurity researchers have disclosed details of a financially motivated data theft extortion campaign that has targeted dozens of organizations across professional, legal, and financial services in the U.S. between January and May 2026. The activity has been attributed by Google Mandiant and Google Threat Intelligence Group (GTIG) to a threat actor dubbed UNC3753, which is also known as