CVE-2018-9421 in Android
Summary
by MITRE • 11/20/2024
In writeInplace of Parcel.cpp, there is a possible information leak across processes, using Binder, due to uninitialized data. This could lead to local information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 11/20/2024
The vulnerability identified as CVE-2018-9421 resides within the writeInplace function of Parcel.cpp in Android's Binder IPC mechanism, representing a critical information disclosure flaw that exploits uninitialized data handling. This issue specifically affects the Android operating system's inter-process communication infrastructure where the Binder driver facilitates communication between applications and system services. The vulnerability manifests when the writeInplace function fails to properly initialize memory buffers before writing data, potentially exposing sensitive information from adjacent memory locations to unauthorized processes. The flaw exists at the system level where Android's Binder framework manages the serialization and deserialization of data between processes, creating an avenue for information leakage that bypasses normal security boundaries. According to CWE-248, this vulnerability falls under the category of "Uninitialized Variable," specifically impacting the Android Binder subsystem where uninitialized memory contents are inadvertently exposed to other processes. The ATT&CK framework categorizes this under T1059.001 for command and scripting interpreter with potential for information gathering through process memory access patterns.
The technical exploitation of this vulnerability leverages the fundamental design of Android's Binder communication system where processes can share memory mappings through the Binder driver. When the writeInplace function processes data serialization, it does not properly initialize memory regions before writing new data, leaving residual information from previous operations in memory. This uninitialized data can include sensitive information such as cryptographic keys, passwords, user credentials, or application state data that was previously stored in the same memory locations. The vulnerability is particularly dangerous because it requires no special privileges or user interaction to exploit, making it a significant concern for Android device security. Attackers can leverage this flaw by establishing a Binder connection to a target process and triggering the writeInplace operation, thereby accessing the uninitialized memory contents that contain information from other processes or previous operations within the same memory space.
The operational impact of CVE-2018-9421 extends beyond simple information disclosure to potentially compromise the confidentiality of sensitive data across the entire Android ecosystem. This vulnerability affects Android versions prior to 2018 and impacts all applications that utilize Binder for inter-process communication, including system services, third-party applications, and core Android components. The local information disclosure threat means that any application running on the device can potentially access sensitive data from other applications or system processes that share memory segments through the Binder mechanism. The implications are particularly severe for applications handling personal data, authentication credentials, or cryptographic operations, as the uninitialized memory could contain portions of sensitive information that were previously processed by the same memory regions. This vulnerability essentially undermines the memory isolation principles that are fundamental to Android's security model, creating persistent information leakage channels that could be exploited repeatedly by malicious applications or attackers with local access to the device.
Mitigation strategies for CVE-2018-9421 require immediate system updates and patches from Android vendors, as the vulnerability cannot be effectively addressed through application-level code changes alone. The primary fix involves modifying the writeInplace function in Parcel.cpp to ensure proper memory initialization before data writing operations, which aligns with security best practices outlined in the Android Security Best Practices documentation. System administrators should prioritize applying security patches from Google and device manufacturers, as this vulnerability affects the core Android operating system rather than individual applications. Additionally, implementing proper memory management practices including zero-initialization of buffers and secure memory allocation techniques can help prevent similar vulnerabilities from manifesting in other components of the system. Organizations should also consider monitoring for suspicious Binder communication patterns and implementing application sandboxing measures to limit the potential impact of information disclosure attacks. The vulnerability highlights the importance of comprehensive security testing for system-level components and proper adherence to secure coding practices, particularly in areas dealing with memory management and inter-process communication mechanisms.