Mobile handsets including iPhones and those using Windows Mobile or Google’s Android operating system are vulnerable to text-based attacks, say experts.

Software code that arrives in a text message can hijack the phones, said Charlie Miller and Collin Mulliner at the Black Hat conference in Las Vegas.

The malware could knock phones off the network or access data and programs.

The team say that hackers could develop programs to exploit the weakness in as little as two weeks.

The pair said that publicising the means of attack was necessary to ensure the problem was addressed.

"If we don’t talk about it, somebody is going to do it silently. The bad guys are going to do it no matter what," Mr Mulliner, an independent security expert, said.

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The hack works by slightly modifying the data that arrives with an SMS message.

The system that processes such messages is similar across different operating systems and can, once compromised, gain access across a range of applications including a phone’s address book or camera.

The team wrote software to exploit the weakness, targeting iPhones on four networks in Germany as well as AT&T in the US. However, they believe it would work equally well in any country.

The approach is particularly dangerous because messages are delivered automatically, and users cannot tell that they have received the malicious code.

The problem could be fixed by directly patching the vulnerability in smartphones’ operating systems, or the network providers could scan for messages that look to be trying to gain access to phones via the malicious code.

They said they informed Apple, Microsoft, and Google of the hack but so far only Google had addressed the problem.

The Black Hat gathering, part of a leading series of conferences for information and computer security experts, took place from 25 to 30 July.

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