A third-party advertising framework integrated in hundreds of Android apps contains a vulnerability that could allow hackers to steal sensitive information from users' phones, according to security researchers from antivirus firm Bitdefender.
The framework is called HomeBase SDK (software development kit) and is developed by Widdit, based in Ramat Gan, Israel. It allows Android developers to monetize their apps by displaying ads and custom content on the phone's lock screen.
HomeBase SDK is one of the many mobile advertising frameworks available to Android developers, but according to the Bitdefender researchers it has an insecure update mechanism that could put users at risk when their phones connect to the Internet over insecure or compromised networks.
Every time an application that uses HomeBase is executed, the SDK code embedded into it connects to a remote server using an unencrypted connection to get the latest version of the SDK, the Bitdefender researchers said Tuesday in a blog post. If an updated SDK is found it is downloaded in the form of a JAR (Java Archive) file and executed, they said.
Since the communication with the update server is done via plain HTTP with no SSL encryption, an attacker could intercept the application's request as it travels over an insecure wireless network or a compromised network gateway and serve back a malicious JAR file, according to the Bitdefender researchers.
In addition, the authenticity of the downloaded file is not verified, so the host app has no way of knowing whether the JAR file actually came from Widdit or not, they said.
A malicious JAR file supplied by an attacker would be able to use the permissions granted to the host app, which is another problem, because the HomeBase SDK forces apps to ask for an extensive list of permissions on installation.
"A malicious JAR file could read and export contacts, get the accounts on the device, access the user's location and report it, record audio, read SMS contents and read the user's browsing history and bookmarks, among others," Bogdan Botezatu, a senior e-threat analyst at Bitdefender, said via email.
If the application has any other permissions in addition to the ones required by the HomeBase SDK, the malicious JAR file would be able to use those as well, Botezatu said.
The Bitdefender researchers claim they successfully tested a man-in-the-middle attack in a controlled environment against an app with the HomeBase SDK and managed to make it execute a malicious JAR with phone calling and SMS hijacking capabilities.
"The application downloaded and ran the JAR file and executed the malicious code without objection, as it had been granted phone calling and SMS interception permission upon installation," they said.
The researchers claim the HomeBase SDK doesn't actually need all of the permissions it requests, but Widdit disagrees.
"As a rich and robust lock screen platform, HomeBase does require a relatively high number of permissions in order for it to deliver its full experience in an optimal way," Noam Mor, the head of media relations at Widdit said via email. "That being said, our platform is very flexible and allows developers the option to exclude some of the permissions if they wish to request less permissions (but affect functionality)."