Researchers say sophisticated malware targets banks, telecom companies and public agencies

Cyber-security researchers say they've identified a highly sophisticated computer hacking program that's been used for several years to spy on banks, telecommunications companies and government agencies around the world.

While the source of the "Regin" malware is unconfirmed, experts say it was likely created by the government of some as-yet unidentified country.

Researchers at Symantec, a Silicon Valley security firm, say the malware was designed to collect screenshots, steal passwords and monitor mobile phone calls, among other things, while covering its tracks to avoid being detected. Based on its capabilities, Symantec says Regin is likely "one of the main cyberespionage tools used by a nation state."

Symantec says the malware has been used since at least 2008. Half the known cases of computer infection were in Russia and Saudi Arabia.