Bad actors are hacking and repackaging the most popular paid and free apps for Apple iOS and Google Android devices, a new study finds.

Ninety-two percent of the top 100 paid Apple iOS apps and 100 percent of top 100 paid Android apps have been hacked, says Arxan Technologies in its new report, "State of Security in the App Economy: Mobile Apps Under Attack." The report is based on the study of 230 top apps, both paid and free, for Apple's iOS and Google's Android devices.

Not surprisingly, free apps are also at the mercy of these attackers, with 40 percent of free iOS apps having been hacked, and 80 percent of free Android apps in the same boat.

"We wanted to provide a new, fact-based perspective on the hacking threats that app owners/providers face after releasing their app," says Jukka Alanen, vice president of Arxan. So the report looks at the issues from the developer's perspective rather than the end user's, he says.

How are cybercriminals abusing these mobile apps? By disabling or bypassing security features, unlocking or changing features, selling pirated versions, stealing source code, and spreading malware-infected versions of them, the report says. Gaming, business, productivity, financial services, social networking, entertainment, communication, and healthcare apps are all being targeted.

"So, while piracy is common, there's a wide variety of hacking attack types that we found. All of these attacks can cause significant damage to the application vendor/owner," Alanen says.

Arxan studied hacked versions of mobile apps found on third-party sites outside of Apple App Store and Google Play, such as Cydia, third-party mobile app distribution sites, hacker/cracker sites, and others. "We did not review whether the original applications in Apple App Store or Google Play were already compromised in some way, but know anecdotally that some of the malware found in official app markets has been based on repackaged versions of other pre-existing applications redistributed with malware," Alanen says.

The attackers typically reverse-engineer the app's code and then retool it for their own purposes. "This process is made easy with widely available free or low-cost hacking tools," the Arxan reports says.

App developers are expected to soon take a hit financially, as well, in the wake of this activity, the report says. Mobile app revenues are expected to hit more than $60 billion by 2016, and the volume of mobile payments to hit $1 trillion, according to data from KPMG, ABI Research, and TechNavio.

And yet fewer than 5 percent of popular mobile apps use what Arxan calls "professional-grade" defenses, such as multiple layers of protection, for tamper-resistance.

The study found that some hacked versions of these popular apps had been downloaded more than 500,000 times from these unofficial third-party sites, so users aren't just getting their apps from authorized Apple and Google app stores.

Even so, it's not just those unofficial third-party sites that are dangerous. "It is very important to understand that users do not need to download apps from third-party sites for app owners to suffer from hacking attacks. Intellectual Property (IP) and decompiled source code can be stolen without the hacker republishing the app on third-party sites," according to Arxan's report. "Furthermore, hackers can republish hacked apps on official app stores (e.g., under a different app name). Finally, merely the known existence of a hacked and tampered version can damage the app owner's brand and customers' trust, even if few users download the hacked version."

Arxan won't name names of the hacked apps, however. "Arxan's intention is not to call out any specific app maker or developer for potential security flaws. Rather, we're trying to educate all of the key stakeholders in the broader App Economy about the potential dangers that are out there, as well as some best practices to begin to address this issue," Alanen says.

The full report from Arxan is available for download here.

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