Trustwave's SpiderLabs Security Advisory TWSL2011-008: Focus Stealing Vulnerability in Android https://www.trustwave.com/spiderlabs/advisories/TWSL2011-008.txt Published: 2011-08-06 Version: 1.0 Vendor: Google http://www.android.com/ Product: Android Versions affected: Tested on 2.1 - 2.3 Other versions may also be affected Product description: Android is an open-source software stack for mobile devices which includes an operating system, key applications, and middleware. The Android mobile operating system is based on a modified version of the Linux kernel. Android is currently owned and developed by Google. Credit: Sean Schulte of Trustwave Finding 1: Covert Focus Stealing Android uses Intents and Activities such that the preferred application is always used for any given content/context. For example, a URL can always be opened with the Browser, and an image can be opened with the Gallery, Gmail or Twitter. To make this seamless for the user, switching between Activities always uses the same animation, whether the Activity belongs to the same app or a different app. Additionally, a service running in the background is able to 1) determine which app is currently running in the foreground, and 2) display an Activity defined in its own app (ie, not the current foreground app). These two "features" combine to allow a malicious developer to run a service that looks for apps it knows how to attack, and display a login screen to the user when those apps run. For example, when the user opens an app which requires a login, the malicious service displays a screen that looks identical to the legitimate login screen. Android gives no indication that the login screen actually belongs to a different app, and the Activity-switching animation would be the same whether the real app had legitimately displayed its login screen. In the case of a pixel-perfect malicious login screen, the user would have no visual indication that the focus has switched from the legitimate screen. When the user supplies his credentials, they can be sent to a remote server, allowing the attacker to steal the user's credentials without his knowledge. Any app that supplies a login screen is vulnerable to this attack. Remediation Steps: This vulnerability has not been fixed at the time of this advisory. As an alternative solution, users should be cautious when downloading third-party applications. Because of the nature of the vulnerability, a malicious application must be installed for a user to be vulnerable. Revision History: 03/18/11 - Vulnerability Disclosed to Google 07/08/11 - Publication/Disclosure Discussed with Vendor 08/06/11 - Advisory Published About Trustwave: Trustwave is the leading provider of on-demand and subscription-based information security and payment card industry compliance management solutions to businesses and government entities throughout the world. For organizations faced with today's challenging data security and compliance environment, Trustwave provides a unique approach with comprehensive solutions that include its flagship TrustKeeper compliance management software and other proprietary security solutions. Trustwave has helped thousands of organizations--ranging from Fortune 500 businesses and large financial institutions to small and medium-sized retailers--manage compliance and secure their network infrastructure, data communications and critical information assets. Trustwave is headquartered in Chicago with offices throughout North America, South America, Europe, Africa, China and Australia. For more information, visit https://www.trustwave.com About Trustwave's SpiderLabs: SpiderLabs(R) is the advanced security team at Trustwave focused on application security, incident response, penetration testing, physical security and security research. The team has performed over a thousand incident investigations, thousands of penetration tests and hundreds of application security tests globally. In addition, the SpiderLabs Research team provides intelligence through bleeding-edge research and proof of concept tool development to enhance Trustwave's products and services. https://www.trustwave.com/spiderlabs Disclaimer: The information provided in this advisory is provided "as is" without warranty of any kind. Trustwave disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. 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