CVE-2021-39765 in Android
Summary
by MITRE • 03/30/2022
In Gallery, there is a possible permission bypass due to a confused deputy. This could lead to local information disclosure with User execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-12LAndroid ID: A-201535427
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Analysis
by VulDB Data Team • 04/02/2022
The vulnerability identified as CVE-2021-39765 affects the Gallery application in Android 12L systems and represents a significant security flaw categorized under the confused deputy problem. This type of vulnerability occurs when a system component mistakenly grants privileges to an attacker-controlled process, allowing unauthorized access to protected resources. The issue stems from improper permission handling within the Gallery application's interaction with system components, creating a scenario where malicious actors can exploit the confusion between legitimate and malicious processes to gain unauthorized access to sensitive information.
The technical implementation of this vulnerability involves a confused deputy scenario where the Gallery application fails to properly validate the authenticity of requests it receives from other system components. When a user executes a malicious payload with user-level privileges, the application's permission checking mechanisms become confused, allowing the attacker to bypass normal access controls. This confusion arises from the application's reliance on potentially untrusted input sources without proper authentication verification. The vulnerability specifically affects the way Gallery handles inter-process communication and permission delegation, creating a pathway for local information disclosure attacks that would normally be prevented by proper access controls.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to access sensitive data stored within the Gallery application's protected directories. Attackers with user execution privileges can exploit this flaw to access photos, videos, and other media files that should be restricted to authorized users only. The local nature of this vulnerability means that exploitation does not require network connectivity or user interaction, making it particularly dangerous as it can be leveraged by malware already present on the device. This type of attack aligns with the attack pattern described in the ATT&CK framework under privilege escalation and credential access techniques, specifically targeting local system resources and user data.
Security mitigations for this vulnerability require careful attention to permission handling and inter-process communication protocols within the Gallery application. System administrators and developers should implement proper authentication checks for all incoming requests, ensuring that processes can only access resources they are explicitly authorized to use. The fix typically involves strengthening the permission validation mechanisms and implementing proper delegation controls that prevent the confused deputy scenario. Organizations should also consider applying the relevant Android security patches promptly and conducting thorough security assessments of their mobile applications to identify similar permission bypass vulnerabilities. This issue demonstrates the importance of following secure coding practices as outlined in CWE guidelines for confused deputy problems, which emphasize the need for proper authentication and authorization controls in all system interactions.