An adversary, through a previously installed malicious application, issues an intent directed toward a specific trusted application's component in an attempt to achieve a variety of different objectives including modification of data, information disclosure, and data injection. Components that have been unintentionally exported and made public are subject to this type of an attack. If the component trusts the intent's action without verififcation, then the target application performs the functionality at the adversary's request, helping the adversary achieve the desired negative technical impact.

Prerequisites

An adversary must be able install a purpose built malicious application onto the Android device and convince the user to execute it. The malicious application will be used to issue spoofed intents.

Mitigations

To limit one's exposure to this type of attack, developers should avoid exporting components unless the component is specifically designed to handle requests from untrusted applications. Developers should be aware that declaring an intent filter will automatically export the component, exposing it to public access. Critical, state-changing actions should not be placed in exported components. If a single component handles both inter- and intra-application requests, the developer should consider dividing that component into separate components. If a component must be exported (e.g., to receive system broadcasts), then the component should dynamically check the caller's identity prior to performing any operations. Requiring Signature or SignatureOrSystem permissions is an effective way of limiting a component's exposure to a set of trusted applications. Finally, the return values of exported components can also leak private data, so developers should check the caller's identity prior to returning sensitive values.

Related Weaknesses

References

REF-427

Analyzing Inter-Application Communication in Android
Erika Chin, Adrienne Porter Felt, Kate Greenwood, David Wagner.
https://people.eecs.berkeley.edu/~daw/papers/intents-mobisys11.pdf

Submission

Modifications