CVE-2021-39705 in Android
Summary
by MITRE • 03/16/2022
In getNotificationTag of LegacyVoicemailNotifier.java, there is a possible leak of ICCID due to a permissions bypass. This could lead to local information disclosure with User execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-10 Android-11 Android-12Android ID: A-186026746
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Analysis
by VulDB Data Team • 03/19/2022
The vulnerability identified as CVE-2021-39705 resides within the LegacyVoicemailNotifier.java component of Android operating systems spanning versions 10 through 12. This flaw manifests in the getNotificationTag method where an improper permissions check allows for unauthorized access to sensitive telephony information. The vulnerability represents a critical security gap that enables information disclosure through a permissions bypass mechanism. The affected system components operate under the assumption that proper access controls are maintained, but this weakness creates an avenue for unauthorized data exposure.
The technical implementation of this vulnerability stems from insufficient validation of caller permissions within the notification handling system. When the getNotificationTag method processes requests, it fails to adequately verify whether the calling process possesses the necessary privileges to access ICCID information. This permission bypass occurs at the system level where telephony services should enforce strict access controls but instead permit unauthorized access to subscriber identification data. The flaw operates under the principle that certain system components should not expose sensitive information without proper authorization, yet the current implementation allows for this exposure through a specific code path.
From an operational perspective, this vulnerability creates a significant risk for local information disclosure attacks that require only user execution privileges to exploit. The attack vector does not necessitate user interaction, making it particularly dangerous as it can be leveraged by malicious applications already present on the device. The ICCID information, which uniquely identifies a SIM card, represents sensitive subscriber data that could be used for tracking, identity theft, or targeted attacks against users. This information leak could potentially enable attackers to correlate device usage patterns with specific subscribers, creating privacy and security concerns that extend beyond simple data exposure.
The impact of this vulnerability aligns with CWE-284, which addresses improper access control mechanisms in software systems. This classification indicates that the vulnerability stems from inadequate privilege management and access validation within the Android framework. The ATT&CK framework categorizes this type of vulnerability under T1059.001 for command and script interpreter usage, as attackers could potentially leverage the exposed information to craft more sophisticated attacks. Additionally, this represents a form of information disclosure that could contribute to broader exploitation chains, potentially enabling privilege escalation or lateral movement within the device's security boundaries.
Mitigation strategies should focus on implementing proper permission validation within the getNotificationTag method and ensuring that all telephony-related access controls are properly enforced. Android security updates should include code modifications that verify caller credentials before exposing ICCID information, and developers should implement stricter access control mechanisms for sensitive telephony data. Organizations should also consider applying the latest security patches and updates immediately upon release to prevent exploitation of this vulnerability. The remediation process must address the root cause by strengthening the permission checking mechanism and ensuring that no unauthorized access paths exist for sensitive subscriber information within the telephony notification system.