American and British spy agencies apparently believe there are real-life terrorists lurking among the elves, gnomes and the trolls of online gaming worlds.

For the past several years, the National Security Agency (NSA) and its British counterpart, the Government Communications Headquarters (GCHQ), have secretly monitored activity and harvested data from massively multiplayer online game networks like World of Warcraft and Second Life.

There is little evidence yet that the monitoring has yielded any counterterrorism successes. But the agencies believe terrorists might be using such networks to communicate with each other, move money and plot attacks around the world without being noticed, the New York Times reported Monday, quoting documents obtained from former NSA contractor Edward Snowden.

Agents from NSA and GCHQ have created make-believe characters and entered online fantasy game terrains in an effort to recruit informers and tap communications between players.

"Because militants often rely on features common to video games fake identities, voice and text chats, a way to conduct financial transactions American and British intelligence agencies worried that they might be operating there," the Times reported.

Snowden's latest revelations are sure to provoke more questions about the NSA's breathtaking range of surveillance activities -- especially if it turns out that the agency collected data on U.S. gamers as part of its monitoring efforts.

Just last week, the Washington Post reported on how the agency is daily collecting location data from millions of cellphones around the world, including those belonging to Americans travelling abroad.

The NSA later cited a 1981 Executive Order signed by President Ronald Reagan as the authority under which it is collecting the data. Privacy groups have called the effort unconstitutional and another example of the agency monitoring and gathering data on U.S. residents without a court-issued warrant.

Former NSA security engineer John Pescatore, who is presently director of emerging technologies at the SANS Institute, said the NSA's effort to mine intelligence data from online gaming networks is not all that surprising. "Years ago, law enforcement and the intelligence community were concerned about criminal and terrorist use of online services like AOL or Compuserve," he said. "So, I'm not surprised they would look at the online gaming world -- they are just another form of online service."

According to the Times, documents obtained from Snowden show that the NSA and the GCHQ began taking an active interest in intelligence gathering from the online gaming world between 2007 and 2008.

In one document from around that time, the NSA talked about how it was able to gather information on user accounts, characters and guilds related to known Islamic extremists groups by monitoring World of Warcraft.

Targets of interest appeared to be playing World of Warcraft and other online games, the documents noted. However, there is nothing to show whether those targeted were engaged in any nefarious activities on the networks, the Times said.

By 2008, Britain's GCHQ had established a full-fledged network exploitation team in Second Life and helped London police bust a crime gang that was using the gaming platform to sell stolen credit card information. A similar team on World of Warcraft helped the British spy agency identify engineers, scientists, foreign intelligence operatives and embassy drivers on the network, many of whom were apparently viewed as potential targets for recruitment, the Times said.

The intelligence gathering effort gathered intensity in 2009. In one episode, the GCHQ apparently harvested three days' worth of instant messages, chats, communications and financial transaction data from Second Life while testing its spying abilities on the network.

The documents apparently do not specify how the NSA or its counterparts in other countries got access to gamer accounts and communications data. Nor do the documents provide any information about how many game users may have been monitored or whether information was collected on any Americans.

The makers of the gaming platforms themselves appear to be unaware of the spying. The creators of World of Warcraft, for instance, claimed they had not been contacted or informed of the data mining on their networks by either the NSA or the GCHQ.

Jaikumar Vijayan covers data security and privacy issues, financial services security and e-voting for Computerworld. Follow Jaikumar on Twitter at @jaivijayan or subscribe to Jaikumar's RSS feed . His e-mail address is jvijayan@computerworld.com.

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