CVE-2023-21138 in Android
Summary
by MITRE • 06/15/2023
In onNullBinding of CallRedirectionProcessor.java, there is a possible long lived connection due to improper input validation. This could lead to local escalation of privilege and background activity launches with User execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11 Android-12 Android-12L Android-13Android ID: A-273260090
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Analysis
by VulDB Data Team • 07/14/2023
The vulnerability identified as CVE-2023-21138 resides within the Android operating system's CallRedirectionProcessor.java component, specifically in the onNullBinding method where improper input validation creates a persistent connection risk. This flaw represents a critical security weakness that could enable malicious actors to maintain prolonged system access through compromised call redirection mechanisms. The vulnerability affects multiple Android versions including Android 11, 12, 12L, and 13, indicating a widespread impact across the Android ecosystem. The issue stems from inadequate validation of input parameters during the binding process, allowing for potentially malicious connections to persist longer than intended. This long-lived connection capability creates an exploitable vector for attackers to establish sustained access to affected devices.
The technical implementation of this vulnerability involves the improper handling of null binding scenarios within the call redirection framework, which operates at a system level within Android's telephony services. When the system encounters a null binding condition, the flawed input validation prevents proper connection termination or cleanup, resulting in persistent network connections that remain active beyond normal operational parameters. This behavior creates opportunities for privilege escalation as the persistent connection can be leveraged to execute background activities with user-level privileges. The vulnerability's classification aligns with CWE-20, which addresses improper input validation, and represents a significant concern for Android's security architecture. The exploitation requires no user interaction, making it particularly dangerous as it can be triggered automatically without any conscious action from the device user.
The operational impact of CVE-2023-21138 extends beyond simple connection persistence, as it enables local privilege escalation and unauthorized background activity execution. Attackers can potentially use this vulnerability to gain elevated privileges on affected devices, allowing them to perform actions that would normally require higher system permissions. The background activity launches represent a serious concern as they can operate silently in the background, potentially collecting sensitive data, executing malicious code, or maintaining persistent access to compromised systems. This vulnerability directly impacts Android's security model by creating potential attack vectors that bypass normal privilege boundaries. The Android ID A-273260090 indicates this was properly tracked and documented within Google's security infrastructure, highlighting the severity and recognition of the issue within the Android security community. The vulnerability affects core telephony services, making it particularly dangerous as it can compromise communication functions that users rely on for both personal and professional purposes.
Mitigation strategies for this vulnerability should focus on immediate patch deployment across all affected Android versions, as well as implementing network monitoring to detect persistent connections that may indicate exploitation attempts. System administrators and device manufacturers should prioritize updating affected devices to the latest security patches provided by Google. Network segmentation and monitoring solutions should be implemented to detect anomalous connection patterns that could indicate exploitation of this vulnerability. The recommended approach includes disabling unnecessary telephony services when not required and implementing strict input validation controls at the application level. Additionally, device users should be educated about the importance of keeping their systems updated and should avoid installing untrusted applications that might exploit this vulnerability. Security professionals should monitor for indicators of compromise related to persistent network connections and unusual background activity patterns. The ATT&CK framework would categorize this vulnerability under T1059 for command and scripting interpreter and potentially T1068 for exploit for privilege escalation, making it a critical concern for enterprise security teams. Organizations should implement comprehensive vulnerability management programs that include regular security assessments and monitoring of system connections to prevent exploitation of this long-lived connection vulnerability.