Google has pulled multiple Android apps that relied on a popular mobile app library that posed a severe security risk.
The ad library, codenamed “Vulna” (or Ap Vulna") by FireEye, the net society firm that uncovered the threat, aggressively collects sensitive data as well as being able to perform dangerous operations such as phoning home to a command-and-control server before downloading and running secondary components on demand.
In the two weeks since the alarm about Vulna first went out, Google has removed numerous apps from Google Play that relied on the technology. It has also cancelled a number of Developer accounts, as a follow-up blog post on the issue by FireEye explains.
A number of these vulnaggressive apps and their developers’ accounts have been taken down from Google Play, including app developer Main Games Mobile, Itch Mania and Popadworld. The total number of downloads of these apps was more than six million before the take-down. Sadly, while removing these apps from Google Play prevents more people from being infected, the millions of devices that already downloaded them remain vulnerable.
Second, a number of apps from the list that we reported to Google and Ad Vulna have updated the ad library included in the app to the newest version, which fixes many of the security issues we found. Moreover, a number of other apps, such as Mr. Number Blocker with more than 5 million downloads, have simply removed the vulnaggressive ad library Ad Vulna. The total number of downloads of these apps before they were updated was more than 26 million. Unfortunately, many users do not update their downloaded apps often, and hence millions of users of these apps will still be vulnerable until they update to the latest version of the apps.
The move is welcome but fails to deal with the legacy problem of users who are using older versions of apps the incorporate the dodgy Vulna code. According to the latest estimated from FireEye, more than 166 million downloads from Google Play featured apps including other versions of the ad library.
Vulna is a codename and FireEye is yet to name the developer of the mobile ad library it argues created a new class of vulnerability for Android users. FireEye recently announced a cloud-based mobile threat prevention technology. The new product, FireEye Mobile Threat Prevention, based on virtual machine-based threat protection and targeted at securing the Android platform, is due to be generally available by the end of 2013. The launch of the product explains FireEye's interest in Vulna.
Ad libraries in general present privacy risks such as collecting device identifiers (IMEI, IMSI, etc) and location information. But Vulna went far further than this and its built-in functionality allowed it to collect highly sensitive information such as text messages, phone call history, and contact lists. It can also performs dangerous operations such as executing dynamically downloaded code. All this functionality is controlled by remote servers.
Security shortcomings of the software include its use of unsecured HTTP for receiving commands and the dynamic loading of code from its control server. This means a skilled hackers might be able to hijack the update process towards their own ends, something that might potentially be used to steal two-factor authentication tokens sent via SMS, or even turn the device into part of a mobile botnet, as previously reported in our earlier story about the threat.
FireEye notified both Google and the unnamed developer of the software. ®