Those popular mobile apps that everyone's buying from the official Android and Apple apps stores for business and fun are being torn apart by hackers who turn around and post these abused apps filled with malware, their content pirated or otherwise tampered, according to a study out today.
Security vendor Arxan, which makes tools for hardening applications from tampering, says it wants to make this point about apps abuse with its study that describes how it found that 92% of the top 100 paid apps being sold in the Apple App Store had been hacked in various ways, and so had a full 100% of the top 100 apps originally found in Google Play.
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"As a hacker, you can take the official application and make it free, and have hidden malware -- the original app owner doesn't know," says Jukka Alanen, vice president of business development at Arxan Technologies and author of the study, "Mobile Apps under Attack."
Beyond its look to find pirated and malware-laden versions of paid apps, Arxan also says it found that 40% of the top 15 free Apple iOS apps and 80% of the top 15 free Android apps (based on May 2012) were found to be hacked in a similar way.
The hacked apps that Arxan discovered included not just knock-offs of the popular Angry Birds app, but also an app for voice translation, games like Flick Homerun and tools such as Beautiful Widgets from LevelUpStudio.
Alanen says Arxan's research on legit apps that had been pirated and tampered with in some way was done by scouring online resources to find them. For instance, to look for Apple iOS apps, Arxan hunted through the Cydia service which has Cydia software for download that acts as a channel to find both free and paid apps for jailbroken Apple iOS devices.
As a kind of unsanctioned Apple app store, "it's a channel to find these sources," Alanen says. Arxen's hunt for knock-offs of legitimate apps also involved looking around for pirated Android apps, scouring places like iCracker and torrent-based sites. Alanen says there's a problem out there with intellectual property and decompiled apps source code being reused without the owner's permission to create new apps as well, such as versions of games without ads, for instance.
It's all not that hard to do, he asserts. Hackers can "reverse engineer the app" using tools that are freely available online, then tamper with the code, adding features and capabilities, such as video uploads, additional device or operating system support. The hacker can even take stolen code and end up re-publishing it in a different guise to the Apple App Store. Apple does have a process to look for malware, but may not necessarily be sharp in catching pirated code, Alanen says.
With industries like financial services now making official Android and iOS apps available, there is a lot at stake for businesses to prevent their apps from becoming pirated and abused.
According to the Arxan report, it's not hard to rip up legit apps. Many free or low-cost decompilation tools and disassembly and debugging tools, such as IDA Pro, exist that would allow a hacker to reverse engineer and in many cases to translate a binary app code back into its source code. "Especially Android Java apps can be easily and trivially decompiled back to source code. Native Android and iOS apps are relatively easy to reverse-engineer as well," the Arxan study says.
While encryption can slow down the hacking process, it doesn't always stop it. "Encrypted apps can be cracked easily by hackers by getting ('dumping') the code from the device memory (where it is running in decrypted form during app execution)," the Arxan report states. This is done with hacking tools like Clutch for iOS.
Legit Apple IOS apps downloaded from the Apple App Store are digitally signed through an encryption process to indicate the owner and the Apple imprimatur -- and apps can't run on Apple devices unless they're signed. The pirated Apple apps, though, are published on third-party sites and can be used by jailbroken Apple devices.
Android apps, though not signed by Google, can be self-signed digitally by the app's owner, Arxan points out. But pirated versions of legit apps can be modified to bypass any licensing checks implemented in the code. The successful hacker can even re-sign it with his own encryption key.
In all of this, Arxan asserts its technology can be applied to compiled or binary code of apps to harden them against reverse-engineering that hackers may try. Privately held Arxan, which received national security-driven funding when in the early stages of research and development at Purdue Research Park, is said to be used by the U.S. Department of Defense today for hardening applications against tampering.
