CVE-2023-21172 in Android
Summary
by MITRE • 06/28/2023
In multiple functions of WifiCallingSettings.java, there is a possible way to change calling preferences for the admin user due to a permissions bypass. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-13Android ID: A-262243015
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Analysis
by VulDB Data Team • 07/21/2023
The vulnerability identified as CVE-2023-21172 resides within the WifiCallingSettings.java component of Android 13 operating systems, representing a critical permissions bypass flaw that enables local privilege escalation. This issue affects the core telecommunications settings functionality where administrative calling preferences can be modified without proper authorization, creating a significant security gap in the Android framework. The vulnerability stems from inadequate access controls within multiple functions of the wifi calling settings implementation, allowing unauthorized modification of system-level calling parameters that should be restricted to administrative users only. The flaw exists in the Android platform's permission model where the standard security boundaries are being circumvented through improper validation of user privileges during settings modification operations. This type of vulnerability falls under the CWE-284 access control weakness category, specifically addressing improper access control mechanisms within the Android operating system's telecommunications subsystem. The Android ID A-262243015 further identifies this as a platform-level security issue affecting the system's ability to properly enforce user privilege restrictions. The exploitation of this vulnerability requires no user interaction and does not necessitate additional execution privileges, making it particularly dangerous as it can be leveraged by any local attacker with basic system access. The impact extends beyond simple preference changes to potentially enable more severe attacks by allowing modification of calling behavior that could be used for surveillance or communication disruption purposes.
The technical implementation of this vulnerability involves the manipulation of multiple functions within the WifiCallingSettings.java file where access control checks are either missing or improperly enforced. When administrative users attempt to modify calling preferences through the wifi calling settings interface, the system fails to properly validate whether the requesting user possesses the necessary administrative privileges. This allows standard users or malicious applications running with local privileges to bypass the normal administrative access controls and modify critical calling parameters that should be restricted. The flaw demonstrates a clear breakdown in the Android security model's enforcement mechanisms, where the system fails to properly authenticate and authorize users before allowing modifications to sensitive telecommunications settings. The lack of proper input validation and privilege checking in these functions creates a pathway for privilege escalation that can be exploited without requiring additional malicious code or elevated privileges. The vulnerability's persistence across multiple functions within the same file indicates a systemic issue in the codebase's approach to access control enforcement rather than isolated function-level problems. This pattern of multiple affected functions suggests that the root cause lies in the underlying architectural approach to privilege management within the wifi calling settings component.
The operational impact of CVE-2023-21172 extends significantly beyond simple configuration changes, as it enables potential attackers to manipulate critical telecommunications functionality that could be used for surveillance, data exfiltration, or communication disruption. An attacker who successfully exploits this vulnerability can modify calling preferences to redirect calls, disable emergency services, or manipulate call routing in ways that could compromise user privacy and security. The local escalation of privilege aspect means that any application or user with basic system access can potentially gain administrative control over calling preferences, which could be leveraged as a stepping stone for more extensive attacks. The vulnerability's nature as a permissions bypass creates a persistent threat vector that remains active as long as the affected Android version is running on the device. The lack of user interaction requirement makes this vulnerability particularly concerning for mobile environments where devices may be left unattended or accessed by unauthorized individuals. This type of vulnerability directly impacts the Android platform's integrity and confidentiality guarantees, as it allows unauthorized modification of system settings that are meant to be protected from casual or malicious interference. The potential for this vulnerability to be chained with other exploits makes it a particularly dangerous security flaw in the Android ecosystem, as it could enable attackers to establish persistent access to critical telecommunications features.
Mitigation strategies for CVE-2023-21172 should focus on immediate patching and system updates from Google, as the vulnerability resides in core Android platform components that require official security updates to resolve. Organizations and users should ensure that their Android 13 devices are updated to the latest security patches available from Google, as these patches will contain the necessary fixes to address the permissions bypass issue in WifiCallingSettings.java. System administrators should implement monitoring for unauthorized changes to telecommunications settings and establish baseline configurations that can detect when calling preferences are being modified outside of normal administrative procedures. The vulnerability's nature as a platform-level issue means that device manufacturers must ensure their security update mechanisms are functioning properly and that users receive timely patches for their specific device models. Additional defensive measures include implementing application whitelisting to restrict which applications can access telecommunications settings and establishing network-level monitoring to detect unusual calling behavior that might indicate exploitation attempts. The mitigation approach should also include user education about the importance of keeping devices updated and the risks associated with running outdated Android versions that may contain unpatched security vulnerabilities. Organizations should consider implementing mobile device management solutions that can enforce security policies and automatically apply security updates to prevent exploitation of this vulnerability. Security teams should monitor for any reported exploitation attempts and prepare incident response procedures that address potential privilege escalation scenarios involving telecommunications settings.