Microsoft on Friday said a hacker group linked to Iran unleashed cyber attacks on US journalists, government officials and accounts associated with a US presidential campaign. Only four accounts were compromised as a result of the “significant cyber activity of the threat group,” Tom Burt, Microsoft’s corporate vice president of computer security and trust, said in an online post. A group Microsoft dubbed “Phosphorous” tried to identify email accounts of targets that included US officials, journalists covering global politics, prominent Iranians living outside that country, and a presidential campaign, according to Burt.