There's a scary new piece of malware that collects call logs, phone-book contacts and other sensitive information from Apple iPhones and iPads. Should you be worried?

The malware was first discovered by researchers at Palo Alto Networks who dubbed it WireLurker and said it exhibited behavior that had never been seen before in malicious software targeting Apple's platforms.

It works by infecting software downloaded from the Web into a desktop or laptop computer. Once installed, the malware waits for an iPhone or iPad to be connected via USB, then it scans the mobile device to see what software it contains. If a target app is installed, it copies the app from the mobile device to the desktop or laptop PC, infects the app and then copies it back.

Once infected, the malware appears to collect data from the user but, to date, no other malicious activity has been discovered, said Palo Alto Networks.

For hundreds of millions of Apple iOS users, malware is a scary prospect. The platform has seen so few attacks that many users don't run antivirus software.

If you're one of them, you probably don't have much to worry about from WireLurker.

The primary route of initial infection has been through several hundreds apps offered through a third-party Chinese software site called Maiyadi, so if you've kept away from that you're almost certainly safe.

Secondly, the malware primarily targets iPhones that have been "jailbroken" -- that is had some of their security removed so certain apps can be run on them. There is a version that targets conventional iPhones and carries an Apple digital security certificate, but researchers say even that version requires that users approve it before it runs.

And finally, it targets popular Chinese apps like Taobao, Alipay or Meitu, so if you're not running those, you have another layer of protection.

Palo Alto Networks estimates several hundred thousand iPhone and iPad users have nonetheless been infected.

For the rest, Apple has blocked affected apps so that should halt infection this time.

The limited nature of the security problem might turn out to be a blessing in disguise. Engineers at computer security companies and Apple will be able to analyze the way WireLurker works and prevent similar malware from spreading the same way in the future.

Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is [email protected]