CVE-2023-21378 in Android
Summary
by MITRE • 10/30/2023
In Telecomm, there is a possible way to silence the ring for calls of secondary users due to a missing permission check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 11/22/2023
The vulnerability identified as CVE-2023-21378 resides within the Telecomm component of a mobile operating system, specifically affecting secondary user accounts on devices running the affected software version. This flaw represents a critical permission boundary violation that allows an attacker to manipulate call routing behaviors without requiring any additional privileges or user interaction. The issue manifests when secondary users experience silenced ring tones during incoming calls, indicating a deliberate disruption of normal communication protocols that should be accessible to all users regardless of their account status.
The technical root cause of this vulnerability stems from insufficient access control validation within the telephony subsystem. When secondary users receive calls, the system fails to properly verify whether the calling user has appropriate permissions to modify or suppress ring tone behaviors for other accounts. This missing permission check creates an exploitable condition where unauthorized actions can be performed within the context of the telephony service. The vulnerability operates at the system level where privilege escalation occurs without requiring additional execution privileges, making it particularly dangerous as it can be exploited by any local user with minimal attack surface requirements. The absence of user interaction requirements further compounds the risk, as exploitation can occur automatically without any need for social engineering or manual intervention.
The operational impact of this vulnerability extends beyond simple call disruption, as it represents a fundamental breakdown in the security model of the operating system's user account management. Attackers can leverage this flaw to gain elevated privileges within the system, potentially accessing sensitive data or performing unauthorized actions that should be restricted to primary users or administrative accounts. The local escalation of privilege aspect means that malicious actors can operate from the perspective of a secondary user account but achieve the same system-level access as primary users, effectively bypassing the intended security boundaries between different user contexts. This vulnerability directly impacts the principle of least privilege and could enable further attacks such as data exfiltration, system modification, or persistent access to the device.
Mitigation strategies should focus on implementing proper access control checks within the telephony subsystem, ensuring that all permission-based operations validate user credentials and account status before executing privileged actions. System administrators should deploy security patches immediately upon availability and consider implementing additional monitoring for abnormal telephony behavior patterns. The vulnerability aligns with CWE-284, which addresses improper access control issues, and maps to ATT&CK technique T1068, which covers local privilege escalation through system vulnerabilities. Organizations should also implement device hardening measures including regular security assessments and user access reviews to prevent exploitation of similar permission boundary flaws. The affected system components should undergo comprehensive security testing to identify and remediate other potential access control violations that could provide similar escalation paths.