The campaign revolves around infecting Mac OS X applications with ‘WireLurker,’ which collects call logs, phone book contacts and other sensitive information on Apple mobile devices.
Some 467 Mac OS X applications offered on a Chinese third-party application store called Maiyadi were found to have been seeded with WireLurker, including “The Sims 3,” “International Snooker 2012” and “Pro Evolution Soccer 2014,” according to Palo Alto’s research paper.
Over the last six months, those applications and others have been downloaded 356,104 times ”and may have impacted hundreds of thousands of users,” the paper said.
Apple advises that users stick to downloading applications from its App Store, which it closely vets, and stay away from third-party stores for security reasons.
It would appear some people turn to the Maiyadi store because it offers applications for free, said Ryan Olson, intelligence director for Palo Alto Network’s Unit 42, the company’s threat intelligence branch.
Palo Alto analysed three versions of WireLurker, each of which were improvements on the previous one, Olson said in a phone interview. But it doesn’t appear the WireLurker attack progressed beyond collecting data from mobile devices.
“We think we sort of caught someone developing the attack, and they haven’t gotten to the point of launching the full attack,” Olson said. “From our perspective, it still looks like an information gathering operation.”
The WireLurker attack is notable for how it leverages desktop Mac applications as part of the attack on iOS. If someone downloaded a Mac OS X desktop application from Maiyadi, WireLurker came along with it.
WireLurker then waits for when an iOS device is connected by a USB cable. A second version of WireLurker checks if the Apple device was ‘jailbroken,’ the term for removing restrictions that Apple uses to prevent users from running applications it has not approved.
Then it would look to see if applications such as Taobao, Alipay or Meitu, a photo editing application, were installed, Olson said. If so, it would copy the application to the desktop Mac, infect it with WireLurker and copy it back to the device.
The third iteration of WireLurker targets iOS devices that are not jailbroken as well. In that version, WireLurker used a digital certificate that Apple issues to enterprise developers so they can run their own applications in-house that do not appear on the App Store.
Using the digital certificate means iOS would allow a third-party application to be installed, although it would display a warning to users, Olson said. If a user approves the installation, WireLurker could be installed along with a legitimate application.
Olson said Palo Alto Networks has been in contact with Apple in the last few days, which is now aware of WireLurker.
“There’s no vulnerability here for them to patch, but they certainly want to be aware of malware and how it works,” Olson said.
Apple could first revoke the enterprise digital certificate that WireLurker’s creators are using, Olson said. The company could also issue an update to detect WireLurker in XProtect, Apple’s antivirus engine, he said.