Which virus was the first to specifically target mobile phones?

The first known virus to target mobile phones was Cabir, a worm that specifically targeted Symbian OS devices. Discovered in 2004, Cabir spread via Bluetooth by masquerading as a security certificate file. Once installed on a device, it would search for other nearby Bluetooth-enabled devices to infect, although its payload was relatively harmless, serving primarily as a proof-of-concept for mobile malware.