CVE-2015-1541 in Android
Summary
by MITRE
The AppWidgetServiceImpl implementation in com/android/server/appwidget/AppWidgetServiceImpl.java in the Settings application in Android before 5.1.1 LMY48I allows attackers to obtain a URI permission via an application that sends an Intent with a (1) FLAG_GRANT_READ_URI_PERMISSION or (2) FLAG_GRANT_WRITE_URI_PERMISSION flag, as demonstrated by bypassing intended restrictions on reading contacts, aka internal bug 19618745.
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Analysis
by VulDB Data Team • 02/03/2018
The vulnerability described in CVE-2015-1541 represents a critical privilege escalation flaw within Android's AppWidget service implementation that undermines the operating system's core security model. This vulnerability exists in the AppWidgetServiceImpl component located in com/android/server/appwidget/AppWidgetServiceImpl.java within the Settings application of Android versions prior to 5.1.1 LMY48I. The flaw enables malicious applications to exploit improper permission handling mechanisms, allowing them to bypass intended restrictions on accessing sensitive user data such as contacts. The vulnerability specifically relates to how the system processes Intent flags that grant URI permissions, creating an avenue for unauthorized data access that should be restricted to legitimate system components.
The technical implementation of this vulnerability stems from a failure in the Android permission model's enforcement mechanisms within the AppWidget service. When applications attempt to send Intents containing FLAG_GRANT_READ_URI_PERMISSION or FLAG_GRANT_WRITE_URI_PERMISSION flags, the system should validate whether the requesting application has proper authorization to grant such permissions. However, the flawed implementation in Android versions before 5.1.1 fails to properly verify these permission grants, allowing malicious actors to craft specially crafted Intents that bypass the normal security boundaries. This represents a classic case of improper input validation and privilege checking, which aligns with CWE-284 Access Control vulnerabilities. The vulnerability specifically targets the system's URI permission handling within the app widget framework, where legitimate system services should maintain strict control over which applications can access user data through widget interfaces.
The operational impact of this vulnerability extends beyond simple data theft, as it represents a fundamental breakdown in Android's security architecture that enables attackers to circumvent the operating system's intended access controls. An attacker who successfully exploits this vulnerability can gain unauthorized access to sensitive user information including contacts, calendar entries, and other personal data that would normally be protected by the system's permission model. This creates a persistent threat vector where malicious applications can maintain access to user data even after the initial attack, as the granted URI permissions can be maintained across system sessions. The vulnerability particularly affects the Android security model's principle of least privilege, where applications should only have access to resources necessary for their operation, and instead allows for broad data access that could be leveraged for identity theft, social engineering attacks, or other malicious activities.
Mitigation strategies for CVE-2015-1541 focus primarily on system updates and security configuration improvements. The most effective immediate solution involves upgrading to Android 5.1.1 LMY48I or later versions where the vulnerability has been patched through improved permission validation mechanisms in the AppWidget service. System administrators should also implement application whitelisting policies that restrict which applications can interact with system widget services, particularly those that might attempt to grant URI permissions. Additionally, mobile device management solutions should enforce stricter monitoring of Intent usage patterns and flag unusual permission granting activities. The vulnerability highlights the importance of proper security testing and code review processes for system-level components, particularly those handling sensitive permission operations. Organizations should also consider implementing network monitoring to detect suspicious Intent traffic patterns that might indicate exploitation attempts, as this vulnerability can be leveraged remotely through malicious applications distributed via third-party app stores or phishing campaigns. This vulnerability aligns with ATT&CK technique T1068, which covers the exploitation of legitimate credentials and privileges for unauthorized access to system resources, and demonstrates the critical importance of maintaining up-to-date security patches across mobile operating systems.