CVE-2019-2127 in Android
Summary
by MITRE
In AudioInputDescriptor::setClientActive of AudioInputDescriptor.cpp, there is possible memory corruption due to a use after free. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android. Versions: Android-7.0 Android-7.1.1 Android-7.1.2 Android-8.0 Android-8.1 Android-9. Android ID: A-124899895.
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Analysis
by VulDB Data Team • 08/01/2020
The vulnerability described in CVE-2019-2127 represents a critical memory corruption flaw within the Android audio subsystem that resides in the AudioInputDescriptor::setClientActive method of the AudioInputDescriptor.cpp source file. This issue manifests as a use-after-free condition that occurs when the system attempts to access memory that has already been deallocated, creating a dangerous scenario where malicious code could exploit this weakness to gain elevated privileges. The vulnerability affects multiple Android versions including 7.0, 7.1.1, 7.1.2, 8.0, 8.1, and 9.0, indicating a widespread impact across the Android ecosystem. The flaw is particularly concerning because it requires no user interaction for exploitation, making it a passive threat that can be leveraged by attackers without any direct user engagement or deception.
The technical nature of this vulnerability places it firmly within the domain of CWE-416 Use After Free, which is classified as a memory safety issue in the Common Weakness Enumeration framework. This weakness specifically addresses situations where software continues to reference memory after it has been freed, leading to unpredictable behavior and potential code execution. The attack vector for CVE-2019-2127 operates through the Android audio framework's client management system, where the setClientActive method fails to properly manage memory references when transitioning between active and inactive states. This use-after-free condition can result in memory corruption that allows an attacker to manipulate the heap, potentially leading to arbitrary code execution with the privileges of the audio service process.
From an operational perspective, this vulnerability creates a significant local privilege escalation risk that could be exploited by malicious applications or processes running on the same device. The attack requires no additional execution privileges beyond what is already available to a standard application, making it particularly dangerous in environments where applications have broad access to system resources. The exploitation process would likely involve crafting a malicious audio input request that triggers the vulnerable code path, causing the system to free memory associated with an audio descriptor and subsequently attempt to access that freed memory. This type of vulnerability is particularly problematic in mobile environments where applications may have extensive permissions and where the attack surface is already large due to the complex nature of mobile operating systems.
The mitigation strategies for CVE-2019-2127 should focus on immediate patching of affected Android versions through official security updates from Google and device manufacturers. Organizations and users should prioritize applying these updates as soon as they become available, as the vulnerability's exploitation does not require user interaction and could be weaponized by threat actors. Additionally, system administrators should consider implementing monitoring for unusual audio service behavior or memory access patterns that might indicate exploitation attempts. The vulnerability's classification under ATT&CK technique T1068 suggests that attackers might leverage this weakness as part of a broader attack chain, potentially using it as a stepping stone to gain access to other system components or escalate privileges to root level access. Device manufacturers should also implement additional memory safety checks and validation mechanisms within the audio subsystem to prevent similar issues from occurring in future implementations.