CVE-2019-9440 in Android
Summary
by MITRE
In AOSP Email, there is a possible information disclosure due to a confused deputy. This could lead to local disclosure of the Email app's protected files with User execution privileges needed. User interaction is needed for exploitation. Product: AndroidVersions: Android-10Android ID: A-37637796
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Analysis
by VulDB Data Team • 09/13/2020
The vulnerability CVE-2019-9440 represents a significant security flaw in the Android Open Source Project Email application that stems from a confused deputy problem within the system's permission model. This issue specifically affects Android 10 and demonstrates how improper handling of inter-process communication can create unexpected access paths for malicious actors. The vulnerability resides in the email application's file access mechanisms where a confused deputy scenario allows for unauthorized file access through carefully crafted interactions between processes.
The technical root cause of this vulnerability lies in the improper validation of inter-process communication requests within the email application's file handling subsystem. When the email app processes file operations, it fails to adequately verify the authenticity and authorization of requesting processes, creating a window where malicious applications can exploit the system's trust relationships. This confusion occurs during the file access validation phase where legitimate system calls are being misinterpreted or improperly validated, leading to unauthorized access to protected email application data. The vulnerability is classified as a confused deputy problem under CWE-284, which specifically addresses improper access control through the manipulation of trust relationships between processes.
The operational impact of this vulnerability is particularly concerning as it requires only user interaction to exploit, making it highly practical for real-world attacks. An attacker must convince a user to perform a specific action within the email application context, such as opening a malicious email attachment or clicking on a crafted link that triggers the vulnerable code path. Once exploited, the vulnerability enables local information disclosure, allowing access to protected email application files that should normally be restricted to the email application's own processes. The attack vector typically involves leveraging the email application's legitimate file access capabilities to gain unauthorized access to sensitive user data, including email messages, attachments, and potentially authentication credentials stored within the email application's protected data stores.
This vulnerability directly relates to the ATT&CK technique T1059.007 for Command and Scripting Interpreter: JavaScript and T1074.001 for Data Staged for Exfiltration, as it enables attackers to access and potentially exfiltrate sensitive email data through legitimate application interfaces. The exploitation process involves creating a malicious application that can manipulate the email application's file handling mechanisms to access protected data. Security professionals should note that this vulnerability represents a classic example of how insufficient input validation and improper access control can create security boundaries that are easily circumvented. The requirement for user interaction makes this attack more difficult to automate but also more likely to succeed in social engineering scenarios where users are tricked into performing actions that trigger the vulnerability.
Mitigation strategies for CVE-2019-9440 should focus on strengthening the email application's process validation mechanisms and implementing more robust inter-process communication security measures. System administrators and device manufacturers should ensure that all affected Android 10 devices receive timely security updates that address the confused deputy scenario in the email application's file access controls. Users should be educated about the importance of not opening suspicious email attachments or clicking on unknown links, particularly when using email applications that may be vulnerable to this type of attack. Additionally, implementing proper privilege separation and access control validation within the email application's file handling code can prevent unauthorized access to protected data. The fix typically involves strengthening the authentication and authorization checks that occur during file access operations, ensuring that only legitimate processes can access protected email application data through proper validation of process identities and permissions.