A new piece of Android ransomware has emerged, capable of locking devices, changing PINs, and even fully wiping user data via factory resets, Symantec researchers warn.
Called "Lockdroid" (Android.Lockdroid.E) by Symantec, the new malware was found trick users into providing it with device administrator rights. As soon as it gains these rights, the malware can encrypt user files and perform other nefarious operations, the security firm said.
As Symantec’s Martin Zhang explains in a blog post, the malware poses as an application for viewing adult content and adopts sophisticated social engineering techniques to gain administrator rights. After installation, it displays a fake “Package Installation” window that tricks users into activating it as a device administrator, thus enabling it to run its more aggressive extortion.
The malicious program is not only capable of encrypting files, locking the device, and performing factory resets, but it also prevents users from uninstalling it through the user interface (UI) or the command line interface, Symantec’s research found.
To display the fake Package Installation dialog, Lockdroid uses a TYPE_SYSTEM_ERROR window, which is displayed on the highest layer on the screen, thus hiding the call to the device administrator requesting API. To eliminate suspicion, after the user clicks the “Continue” button on the fake window, the malware displays a fake “Unpacking the components” dialog.
After waiting for a short time without doing anything, the malware displays a final “Installation is Complete” dialog, which is the step where it gains elevated privileges on the system. For that, it uses a TYPE_SYSTEM_OVERLAY window that is loaded on top of the device administration activation dialog, successfully tricking users into activating its device administrator rights.
According to Symantec, cybercriminals can take advantage of clickjacking techniques to perform other malicious activities as well. Root permissions management, a tool that listens on the system for apps trying to elevate privileges to root (by calling “su”), presents a dialog to the user asking permission on behalf of the app before allowing it to proceed, and malware can abuse this for nefarious purposes.
Google improved the security of Android in version 5.0 Lollipop by preventing the aforementioned dialog types from displaying over the system permission dialog, which means that the clickjacking technique can be used only on devices running OS iterations prior to Android 5.0. However, it still means that around two thirds of the Android devices out there are currently vulnerable to this attack.
The good news, however, is the fact that the offending application, called Porn ‘O’ Mania, is not distributed via Google Play, but can be found in third-party stores, forums, and torrent sites. Symantec explains that users with Google Play installed are protected even if they download it from external sources, because of the Verify Apps option in the Security section of the Settings menu.
To make sure they are fully protected, however, users should download and install applications only from trusted app stores. Furthermore, they should have a security program installed and enabled on their devices, and should make sure that the device and its applications are kept up-to-date at all times.
Android ransomware that changes a device’s PIN code is not new – in September 2015, ESET researchers discovered a similar piece of malware dubbed Android/Lockerpin.A.