Is it legal to lock people out of their own computers? Michael Pollitt examines an online billing system that uses what could be considered strongarm tactics

Ted Kenyon doesn't like being pursued for money by his computer. Retired and living in the west country, he prefers using his PC to download MP3 files. But whenever he turned it on recently, he was confronted by a large popup window demanding payment. He closed it - only to see it instantly appear again.

While advertising popups often plague net users, Kenyon's experience seemed worryingly different. He saw that the window was from a company in Leeds called Micro Bill Systems asking for £19.99, with the explanation that his computer had been used to sign up to a website. After suffering the annoying problem for some time, he emailed the Guardian for help.

Kenyon is always careful about protecting his PC. He was using fully updated Windows XP Professional along with Norton Internet Security 2007, Spybot Search & Destroy, AVG anti-spyware and Sophos anti-rootkit. He'd seen popups before but this one stayed longer each day, hindering his computer use. "The popup starts about 30 seconds after the PC is turned on and lasts for about four minutes before the window can be closed. While the bill is displayed, you cannot minimise it or open any other window in front of it, as it always hogs the top window slot," he says.

Locked out

The Guardian soon found Katie Singleton, who runs her own web business, with the same problem. One day she noticed a window on her PC - headed "MBS direct billing" - demanding money.

"They were charging £19.99 for something called Sexpassport, which I had never heard of and certainly never used. The popup started appearing intermittently and could be clicked out of, but after a few weeks it started to appear more frequently and would then lock me out of the system for up to two minutes," says Singleton. Kenyon and Singleton insist that they never signed up to a website; both fought to regain control of their PCs.

After several unsuccessful attempts, Singleton bought some anti-spyware software from Pareto Logic to do the job. Also struggling, Kenyon eventually followed advice in a user forum and deleted the unwanted files manually.

Other people have been reporting the same thing - an unexpected bill that increasingly disrupts PC use. The website involved is sexxxpassport, operated by an Australian company using billing software provided by Micro Bill Systems. The site offers a three-day free trial for anonymous access, following which charges are made - there's a long list of terms and conditions too.

Simon Briskman, a partner in the technology law group at Field Fisher Waterhouse LLP, worries about the effects such problems have on consumer confidence in the internet. "I think it's very clever," he says. "We haven't seen something like this before and it looks like somebody has thought very carefully through the issues of producing the terms. But all the same, nearly all the victims are going to be consumers and consumer contracts have to be fair - I don't think these terms are fair."

According to the terms, unless the bill is paid, the software will disrupt your computer use for longer each day. There are up to four daily periods of 10 minutes when the window demanding payment is locked and cannot be minimised. Restarting the computer offers no relief and may result in even more disruption.

Briskman also reckons that, if the billing software is installed without consent, it may breach the Computer Misuse Act 1990. But leaving aside the embarrassing suggestion of telling the police you've been involuntarily signed-up to a pornographic website, Briskman offers another solution: "I'm extremely sympathetic with people suffering from this because it's difficult to do anything other than pay these people off. More effectively, complain to the OFT [Office of Fair Trading]."

As the director of malware research at computer security company Prevx, Jacques Erasmus has spent days investigating the software involved. Erasmus started hacking in his early teens, a self-taught skill that led to a challenging IT career. Prevx provides solutions to protect PCs above and beyond the ordinary security software that Kenyon used.

Erasmus signed up a test PC to see how the billing software works. After user permission was given, two mutually protected files were installed in a system directory and the registry modified. The software is then hard for non-technical users to remove. "Once a user's free period has expired, the application installed on the machine will start popping up relentless messages and fullscreen popups that cannot be closed instructing the user to pay their bill," says Erasmus. "These activities are both ruthless and on the borderline of ransomware applications."

So how did Kenyon and Singleton get it? Erasmus has searched hard for an "exploit" where the billing software might be dropped silently onto PCs visiting malicious websites or distributed through other methods such as a botnet. "There is no evidence of it being installed by a dropper of any kind," says Erasmus. "The best way to remove this is to use Prevx1, which will scan your machine to check if you are infected and cure the infection if it is infected." Prevx1 also prevents the software installing in the first place.

Ashley Bateup, the managing director of Micro Bill Systems in Leeds, rebuts any suggestions of silent installations. He says his company has developed a new internet billing system which is used by its only UK customer, sexxxpassport, and claims 100,000 users.

Software removal

"The most common situation giving rise to these complaints is where a member of the household downloads the software without actually reading the terms and conditions or warning, and once they realise they have contracted for a service they refuse to admit their use to the computer owner, who then assumes their PC has been infected in some way," says Bateup. "Our customer service team's experience is that people seem to move into denial with their spouses or partners when pornography use is at question."

If another member of the household is responsible, then the browser history may show this; the company claims to have comprehensive access logs too. Bateup says that one woman who rang to complain was shocked to discover her husband had visited the porn site many times despite his denials. However, Kenyon and Singleton categorically deny that they or anyone else in their households visited the website. So what about software removal for cases like theirs?

"If the software was easily removable few people would pay for the service they had already consumed," says Bateup. "The software operates a reminder procedure to encourage people to settle their accounts. If the consumer settles their account and cancels their subscription, the software can be uninstalled simply."

As to the terms and conditions being lawful and fair, Bateup adds that he contacted the OFT - as well as Trading Standards - last October to inform them of the company's business intentions. Asked about this, the OFT said it does not normally comment on individual cases - which does not resolve whether it thinks MBS's tactics are indeed fair and lawful. The mystery remains, though. Someone must be mistaken. But who?

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