Android Unintended Data Leakage

Unintended data leakage occurs when a developer places sensitive information or data in a location that is easily accessible by other apps on the device.

Android Logs

Logging functionality is used for debugging purposes during development. Android has a class called Log that can be used from within the application to place debug information in a central log. Up until Android 4.1 Jelly Bean applications with the READ_LOGS permission could access log entries from other applications. Therefore any application running on a device that has a version below 4.1 or is rooted is still vulnerable.

This tutorial will demonstrate how sensitive information can be leaked via Android logs. For this demo I will use Insecure Bank, this application contains a number of Android vulnerabilities, if you want to find out how to install click on the link here

Once you have the app setup you should see a login page similar to below. The login credentials to access the app are:

• dinesh/Dinesh@123$
• jack/Jack@123$

Prior to logging in we want try and capture any sensitive information. There are a number of ways of doing this, you can use the logcat option in the Eclipse IDE or adb logcat. A very useful script that comes packaged in Appie is PID Cat, this script filters the logs by application package making it easier to identify information coming from that particular application.

In Appie simply type pidcat com.android.insecurebankv2 (package name). Then log in with the credentials above, you should now see the same credentials displayed in the log.

Another example using the insecure bank application is on the transfer amounts page. You can click on the 'Get Accounts' button and then enter an amount to transfer.

Once you hit the transfer button, the accounts and logs will show up on PID Cat. Again this could be read by other applications.

Logging is an essential feature during development but can inadvertently expose sensitive information. Although it seems trivial, it can lead to serious risk depending on the data that is leaked.

Clipboard Leakage

Another area were sensitive data leakage can occur is from the clipboard. Users tend to copy/paste quite a lot on mobile devices as its easier than typing. If the application allows for the copy/paste of sensitive information from one app to another then it is possible that a malicious application could read it also.

If you take the example below from Insecure Bank, the user can copy out transfer statement information.

We can then use the post-exploitation module in drozer to read the clipboard. To install this module type 'module install clipboard'. Then run the command below

References: https://www.owasp.org/index.php/Mobile_Top_10_2014-M4
                    https://github.com/dineshshetty/Android-InsecureBankv2
                    https://manifestsecurity.com/appie/