CVE-2019-9345 in Android
Summary
by MITRE
In the Android kernel in sdcardfs there is a possible violation of the separation of data between profiles due to shared mapping of obb files. This could lead to local escalation of privilege with User execution privileges needed. User interaction is needed for exploitation.
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Analysis
by VulDB Data Team • 12/13/2023
The vulnerability identified as CVE-2019-9345 resides within the Android kernel's sdcardfs implementation, specifically addressing a critical flaw in the handling of obb (Open Bundle) files that affects the separation of user data between different profiles. This issue represents a significant security concern as it undermines the fundamental principle of data isolation that Android employs to protect user information across different application profiles and user contexts. The vulnerability manifests through the shared mapping of obb files, which are typically used for application data storage and can contain sensitive information that should remain isolated between different user profiles or application contexts.
The technical flaw stems from improper handling of file mappings within the sdcardfs subsystem, which allows for cross-profile access to obb files that should be restricted to specific user contexts. When obb files are shared across different profiles, the kernel's memory management system fails to properly enforce the separation boundaries that should exist between user profiles. This shared mapping mechanism creates a pathway for malicious applications or processes running with user privileges to access data that belongs to other profiles, effectively violating the principle of least privilege and data segregation that forms the foundation of Android's security architecture.
From an operational impact perspective, this vulnerability enables local privilege escalation attacks where an attacker with user-level execution privileges can exploit the shared mapping to gain elevated access to data belonging to other profiles. The requirement for user interaction means that exploitation typically involves social engineering or a compromised application that can execute code in the target user context. However, the implications are severe as successful exploitation can result in unauthorized access to sensitive application data, personal information, and potentially enable further attack vectors such as credential theft or system compromise. The vulnerability affects the core Android security model and can impact all devices running affected kernel versions where sdcardfs is enabled.
The security implications extend beyond simple data access violations as this vulnerability can be leveraged to undermine the entire Android sandboxing architecture. According to CWE classification, this vulnerability aligns with CWE-284 Access Control Issues, specifically addressing inadequate access controls for shared resources. The ATT&CK framework categorizes this under Privilege Escalation techniques where adversaries leverage system flaws to gain elevated privileges. Mitigation strategies should focus on implementing proper kernel updates that address the shared mapping implementation, enforcing stricter file access controls, and monitoring for suspicious file access patterns across user profiles. Additionally, system administrators should consider disabling sdcardfs if not required, implementing proper application sandboxing, and ensuring regular security patches are applied to maintain the integrity of the Android security model. The vulnerability underscores the importance of maintaining strict separation between user profiles and highlights the critical need for robust kernel-level security controls to prevent cross-profile data leakage and unauthorized privilege escalation.