Advertising Week Europe: Frank Abagnale, portrayed in Spielberg's Catch Me if You Can, and now an FBI security expert, warns of danger to children

Frank Abagnale, the man dubbed the world's greatest conman, has issued a stark warning about the dangers of identity theft and children using Facebook.

Abagnale, portrayed by Leonardo DiCaprio in Steven Spielberg's film Catch Me If You Can, said that children in particular need to be made aware of the serious risks of unwittingly revealing information on social networking sites.

He has nearly 40 years experience as a security expert for US law enforcement agencies, having switched sides when he was eventually caught by the FBI after spending half his teenage years on the run as a confidence trickster, imposter, cheque forger and escape artist in the 1960s.

"I'm not on it [Facebook, but] I have no problem with it," he said, addressing the Advertising Week Europe conference in London on Wednesday. "I have three sons on it. I totally understand why people like it. But like every technology you have to teach children, it is an obligation of society to teach them how to use it carefully."

He said having accrued 37 years' work with the FBI he has also become aware of many widely available techniques to gather dangerous amounts of personal data from Facebook.

He gave the example of a creeper virus that allows the tracking of a Facebook user even if their phone is not transmitting.

Another readily available programme, which Abagnale said is owned by Google, uses facial recognition that can match an individual with their personal information on the social networking website "in just seven seconds".

"If you tell me your date of birth and where you're born [on Facebook] I'm 98% [of the way] to stealing your identity," he said. "Never state your date of birth and where you were born [on personal profiles], otherwise you are saying 'come and steal my identity'."

He also advised Facebook users to never choose a passport-style photograph as a profile picture, and instead use group photographs.

Abagnale, who uses a document shredder so he knows that even the FBI cannot reassemble the paper, also warned about the dangers of the seemingly innocuous details given away by users who "like" Facebook postings.

Con air … Leonardo DiCaprio as Frank Abagnale Jr in Steven Spielberg's Catch Me If You Can. Photograph: Moviestore Collection/Rex Features

"What [people] say on a Facebook page stays with them," he said. "Every time you say you 'like' or 'don't like' you are telling someone [things like] your sexual orientation, ethnic background, voting record."

He said he has a "tremendous amount of respect" for the UK's privacy laws, which are "way ahead" of the US.

Abagnale said that while it was common to see companies such as Facebook being criticised for privacy issues in the media, it is up to people to take action to keep their data private.

"Your privacy is the only thing you have left," he said. "Don't blame all the other companies – Google, Facebook – you control it. You have to keep control of your own information."

Between the ages of 16 and 21 Abagnale claims to have impersonated airline pilots, a doctor and a lawyer while forging and cashing $2.5m in cheques and employing other confidence scams. However, he has admitted in the past that his co-writer on the book Catch Me If You Can, on which the DiCaprio film was based, "over dramatised and exaggerated" some of his exploits.

The 64-year-old, who said he has voluntarily paid back every penny he gained illegally, added that airline Pan Am estimates he flew more than a million miles for free on 250 aircraft to 26 countries during his teenage crime spree.

He said that counter-intuitively the rise of technology has made it harder, not easier, for law enforcement. "What I did 40 years ago as a teenage boy is 4,000 times easier now," he said. "Technology breeds crime."

He gave the example of creating a fake British Airways cheque which in his time required finding a $1m printing press the size of an auditorium and three operators. He managed this himself with scaffolding.

"Today one simply opens a laptop," he said. "Each time we add technology it makes it a little easier for criminals. I would have thought technology would have made it harder to do what I did."

He also lamented the rise of an iPhone generation of children who have come to rely on technology and have lost the ability to be resourceful in a more traditional way.

"It is unfortunate today that many young children are not resourceful," he said. "If you took a child in London and took their iPhone and took them somewhere else in the country they'd probably not be able to find their way back. That's a shame."

He added that he avoids the trappings of fame – books, a current TV series, a broadway musical and dozens of offers to front shows and make guest appearances – and has perhaps surprisingly not benefited from royalties or fees due to restrictions of his FBI contract.

Abagnale said he had "nothing to do with the film Catch Me If You Can but was happy Steven Spielberg recreated a relatively realistic version of his life, despite some factual errors. His father, portrayed in the film by Christopher Walken, in fact died while Abagnale was in jail in France aged 21. He did not see him again after he ran away from home after his parents divorced when he was 16.

Despite the glamorous image built up around his past, the 64-year old admitted remorse for his actions.

"I always knew I would get caught. Only a fool would think otherwise. The law sometimes sleeps, it never dies. Some say you were brilliant, a genius, I was neither, I was a child. If I had been brilliant or a genius I wouldn't have needed to break the law just to survive. I've had to live with it the rest of my life".

Abagnale said he has turned down three pardons from three different US presidents.

"I do not believe, nor will ever believe a piece of paper will excuse my actions. Only my actions will."

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