Flame can gather data files, change settings on computers, turn on PC microphones to record conversations, take screenshots and log instant messaging chats.
Kaspersky Lab said Flame and Stuxnet appear to infect machines by exploiting the same flaw in the Windows operating system and that both viruses employ a similar way of spreading.
That means the teams that built Stuxnet and Duqu might have had access to the same technology as the team that built Flame, Schouwenberg said.
He said that a nation state would have the capability to build such a sophisticated tool, but declined to comment on which countries might do so.
The question of who built Flame is sure to become a hot topic in the security community as well as the diplomatic world.
There is some controversy over who was behind Stuxnet and Duqu. Some experts suspect the US and Israel, a view that was laid out in a January 2011 New York Times report that said it came from a program begun around 2004 to undermine what they say are Iran’s efforts to build a bomb.
The US Defense Department, CIA, State Department, National Security Agency and US Cyber Command declined to comment.