Siri divulges personal info when your iPhone is locked

We have a theory that some men may have bought an iPhone 4S for a bit of female companionship. Why not? She's intelligent, gives as good as she gets and has a sense of humour. And they'll never have to worry about her running off with the milkman -- but due to a security issue unearthed by Macworld, she might flirt with him.

Siri, it transpires, can be commanded by anyone to send a text or email to a contact while the phone is locked. This makes some potentially serious pranking tantalisingly possible.

Imagine if a stranger found your iPhone, held down the home button and said, "Siri, text Mum, tell her I'm OK and not to panic!" before turning the phone off. Mass hysteria ensues. Not only that, but Siri will also divulge your contact information, addresses and calendar appointments to anyone, like a drunk spy at a party.

Apple obviously included the feature for the convenience of not having to unlock your phone to access Siri and fortunately it can be disabled. First you need to set a password lock. Then you navigate to Settings > General > Passcode Lock and change the required setting.

After that, whenever you hold down the home button, you'll be greeted with the passcode lock screen. After inputting the code you'll then get access to Siri. Head over to our sister site CNET.com for a handy video that takes you through the steps.

While it presents a minor inconvenience, it addresses the wider issue of security, and the fact that you must be slightly barmy these days not to protect your many email, social-networking and online banking accounts from outsider intrusion.