Gunmen attacked the Microsoft office in Athens' Maroussi suburb, in the early hours of Wednesday June 27, 2012. Attackers drove a van through the front doors of the building, before setting the vehicle on fire using gas canisters. The bombers ordered the security staff to leave the facility.
Although there were no injuries from the attack, Microsoft employees remained at home for the day. The fire caused an estimated 60,000 euros-worth of damage.
Thus far, no one has claimed responsibility for the attack. Greece's anti-terrorism squad is currently investigating the matter.
According to a Fox News article, police believe three individuals were in the van.
Greece has faced similar attacks in the past, typically from anarchist groups. The number of arson attacks has recently increased, in the midst of the country's ongoing economic crisis. The attacks typically occur late at night and do not target individuals.
Read this BBC article on the attack for more information.