Pierluigi Paganini January 29, 2016

Experts at Symantec detected Lockdroid a new piece of Android ransomware capable of locking devices and fully wiping user data via factory resets.

A new strain of ransomware called Lockdroid (Android.Lockdroid.E) is threatening Android users. The mobile ransomware has been detected by experts at Symantec, it is able to lock the device, change the PINs, encrypt user data, and perform other operation including fully wiping data forcing a factory reset.

Lockdroid is also able to prevent victims from uninstalling it, even through the command line interface.

“Symantec has found an Android ransomware variant (Android.Lockdroid.E) that uses new tactics, involving a fake package installation, to trick users into giving the malware device administrator rights. As well as encrypting files found on the compromised device, if administrator rights are obtained, the malware can lock the device, change the device PIN, and even delete all user data through a factory reset.” Symantec’s Martin Zhang wrote in a blog post.

This strain of Android ransomware uses clickjacking to become device administrator. It is important to highlight that clickjacking attacks are effective only in versions prior to 5.0 Lollipop that by prevents dialog messages from displaying over the system permission dialog.

This means that at the time I was writing, 67,4% of Android systems are vulnerable to clickjacking.

The experts discovered Lockdroid tricking users into providing it with device administrator rights, it poses as an application for viewing adult content. The application displays a fake “Package Installation” window that tricks users into giving administrator privileges in order to launch malicious operations.

The Lockdroid ransomware displays a TYPE_SYSTEM_ERROR window on the highest layer on the screen to hide the call to the device administrator requesting API, after the user clicks the “Continue” button it displays a fake “Unpacking the components” dialog. The malware wait a few seconds without doing anything, then it displays a final “Installation is Complete” dialog, in this case, it uses a TYPE_SYSTEM_OVERLAY window to hide the window that asks for the activation of administrative privileges.

When the device is infected, users will be prompted to pay a ransom, threatened by the loss of the encrypted data and the submission of the user’s browsing history to all their contacts.

Experts at Symantec observed that the ransomware uses the clickjacking technique to perform other activities, including root permission management on rooted devices.

“An example is root permission management, a tool that is ubiquitous among the growing rooted device user base. This tool listens on the system for any app trying to elevate its privileges to root (by calling “su”) and presents a dialog to the user asking permission on behalf of the app before allowing it to proceed. Using the above window overlaying trick, malware could circumvent this safety feature and operate freely.” continues the post.

Fortunately the malicious application used as the attack vector, the Porn ‘O’ Mania, is not available on the official Google Play, as usual let me suggest to users to download and install applications only from trusted app stores.

Pierluigi Paganini

(Security Affairs – Lockdroid ransomware, Android)

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