CVE-2016-3750 in Android
Summary
by MITRE
libs/binder/Parcel.cpp in the Parcels Framework APIs in Android 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before 2016-07-01 does not validate the return value of the dup system call, which allows attackers to bypass an isolation protection mechanism via a crafted application, aka internal bug 28395952.
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Analysis
by VulDB Data Team • 02/21/2019
The vulnerability described in CVE-2016-3750 resides within the Android operating system's Binder transaction mechanism, specifically in the Parcel framework implementation located in libs/binder/Parcel.cpp. This flaw affects multiple Android versions including 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before the specified date. The core issue involves insufficient validation of system call return values within the Android inter-process communication (IPC) framework, which forms a critical component of the operating system's security model.
The technical flaw manifests when the dup system call is executed within the Parcel framework without proper validation of its return value. The dup system call is responsible for duplicating file descriptors, and in the context of Android's Binder mechanism, it plays a crucial role in maintaining process isolation and security boundaries. When the return value of dup is not validated, attackers can exploit this weakness to manipulate file descriptor duplication operations. This vulnerability specifically targets the isolation protection mechanisms that are fundamental to Android's security architecture, which relies on proper file descriptor management to maintain separation between different applications and system processes.
The operational impact of this vulnerability is significant as it allows attackers to bypass isolation protection mechanisms that are designed to prevent unauthorized access between applications and system components. An attacker who successfully exploits this vulnerability could potentially gain access to resources that should be restricted to specific applications or processes, undermining the core security model of Android's IPC system. The attack vector requires a crafted application that can leverage the improper validation of the dup system call return value to manipulate the file descriptor duplication process, effectively breaking down the security boundaries that separate different execution contexts within the Android environment.
This vulnerability aligns with CWE-252, which addresses "Unchecked Return Value" in security contexts, and demonstrates how seemingly minor oversights in system call validation can lead to substantial security implications. The flaw also relates to ATT&CK technique T1068, which covers "Exploitation for Privilege Escalation," as the bypass of isolation mechanisms can lead to unauthorized access to system resources. The vulnerability specifically affects Android's security model by undermining the integrity of the Binder transaction framework, which is responsible for maintaining proper process isolation and access control between applications and system services.
Mitigation strategies for CVE-2016-3750 primarily involve applying the relevant security patches provided by Google for the affected Android versions. Organizations should prioritize updating their Android devices to versions that include fixes for this vulnerability, particularly those released after the specified date of 2016-07-01. Additionally, implementing proper monitoring and validation of system call return values within custom applications that utilize Android's IPC mechanisms can help detect potential exploitation attempts. Security administrators should also consider deploying application whitelisting policies and monitoring for suspicious file descriptor manipulation patterns that might indicate exploitation attempts. The fix implemented by Google typically involves adding proper validation checks for the return values of system calls like dup within the Parcel framework, ensuring that any failure in the duplication process is properly handled and does not compromise the security model.