Windows worm slips into iOS App Store, climbs into hipsters' pockets

An item of Windows malware has managed to make its way onto Apple's iOS App Store. It's likely to have been an accidental screw-up, but it nonetheless raises concerns about Apple's app-screening process.

The malicious Windows executable was found by a user who downloaded an app called "Instaquotes-Quotes Cards For Instagram" from iTunes before his security software warned him that the file was infected with a worm. A closer look at the incident, which might have easily been a false alarm by his security software, a not infrequent occurrence, revealed that the threat was all too real.

The file contained a worm variously identified as CoiDung-A by Sophos, Worm-VB-900 by ClamAV and VB-CB by Microsoft. Apple pulled the Instaquotes app from the iOS App Store on Tuesday, shortly after it emerged that the app was tainted with malware. The worm at the centre of the security flap is quite old, and hence widely detected, and not especially potent.

The user who downloaded the app posted his discovery on the Apple Support Communities discussion board, where other users were quickly able to confirm that warnings generated by security software were well-founded.

MacRumors reports that the price of the app, which has been available since 19 July, was reduced from $0.99 to free this last weekend. It's unclear how many people download the app.

The malware can't actually run on a Windows PC without first being extracted from the iOS application package, a factor that means it is unlikely even those Mac users who downloaded the app could spread it to their Windows by infecting friends and colleagues. And, of course, iPhones and iPads can't run Windows programs. The tainted app can't infect a Mac OS X machine either.

What's worse than a worm inside an Apple?

The spread of the malware was probably caused by the accidental infection of a developer's computer, although deliberate infection can't immediately be ruled out. The tainted app made it through Apple's approval process, which has to be the main area of concern.

"Perhaps what's most disappointing about the discovery of Windows malware inside an iOS app is that Apple doesn't seem to have conducted a simple virus scan as part of its app-vetting process," notes Joshua Long, in a post on Sophos' Naked Security blog. "Just extracting all files from the package, and scanning them with anti-virus software, would have prevented the Windows malware from getting into the iOS App Store in the first place."

Earlier this month, Apple approved another questionable iOS app. Find and Call collected contact information from smartphones before uploading this data and sending SMS text message spam to a user's contacts, all without warning the user or asking for permission.

The malware embedded in Instaquotes cannot cause any direct harm to Apple smartphones and tablets, unlike Find and Call. However the appearance of a tainted copy of Instaquotes just weeks after the Find and Call security flap suggests it would be unwise to assume Apple's iOS App Store "walled garden" was impregnable.

In fairness it ought to be pointed out iOS malware, certainly on devices that have not been jailbroken, had been virtually unheard of for five whole years from the launch of the App Store up until the start of this month – a huge achievement. ®

Bootnote

Users of Mac desktops who are conscious about internet hygiene often run anti-virus software for much the same reason that it's a useful addition on Linux file-servers and mail-servers: to clear out any Windows-based malware. Even though these machines can't catch a Windows bug they can become "Typhoid Marys" that spread infection. The Flashback Trojan finally proved that Mac malware was a problem and isolated cases of Linux worms have cropped up occasionally for years, but Windows malware remains the biggest enemy.