Android Application Penetration Testing Part – 4

As per my last article(Part 1), ( Part 2), (part-3) we had a look at basic architecture and penetration testing tools and ADB. Now let’s see some entry points for Android application Penetration testing.

From the perspective of security, the manifest file is usually the first thing that a penetration tester will check on an engagement.

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Android Manifest File

• It provides all details about an Android application
• It names the Java package for the application
• It declares all permissions
• It describes Android applications components
• It contains a declaration of a minimum level of API that application requires
• minimum Android version required to run the program
• services

We will use insecurebank.apk application to demonstrate

Allow debuggable: true

If an application is marked as debuggable then any attacker can access the application data by assuming the privileges of that application or can run arbitrary code under that application permission. In the case of a non-debuggable application, an attacker would first need to root the device to extract any data.

Java Debug Wire Protocol is the central link between the Debugger and the JVM instance

Without a rooted phone it is possible to extract the data or run an arbitrary code using application permission

             Before app start   after app start    

Above is the shell access of my personal phone which is not rooted.

Allow backup: true 

This setting defines whether application data can be backed up and restored by a user who has enabled usb debugging. Therefore applications that handle and store sensitive information such as card details, passwords etc. should have this setting set too false to prevent such risks

Open terminal

Cat backup.ab zlib-flate -uncompress > backup_compressed.tar

Permissions

Permission is a restriction that limits access to a part of the code or to data on the device.

Applications that have permission to copy data to external storage should be reviewed to ensure that no sensitive information is stored.

All the permissions that the application requests should be reviewed to ensure that they don’t introduce a security risk.

There are four values that can be used with this attribute:

• Normal
• Dangerous
• Signature
• Signature Or System

Example-

<Permission>

Android: protectionLevel=”signature”

</permission>

Intents

These are the components that are used to bind two or more different Android components together. Intents could be used to perform a variety of tasks, such as starting an action, switching activities, and starting services.

Intents can be used to launch an activity, send it to any interested broadcast receiver components, and communicate with a background service. Intents messages should be reviewed to ensure that they don’t contain any sensitive information that could be intercepted.

<Intent-filter>

<action android: name=”string” />

<category android: name=”string” />

</intent-filter>

Explicit intents connect one activity to another in the same application. These intents designate the target component by its name and they are typically used for application-internal messages – such as an activity launching a sister activity when a user clicks a button.

Implicit intents do not name a target and the field for the component name is left blank. Implicit intents are often used to activate components in other applications. For example, if we want to show the user a location on a map, we can use an implicit intent to request that another capable app show a specified location on a map.

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