CVE-2018-9543 in Android
Summary
by MITRE
In f2fs_format_utils.c WITH_BLKDISCARD is not defined, which may cause the data partition to not be wiped at factory reset, leading to local information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android. Versions: Android-9. Android ID: A-112868088
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Analysis
by VulDB Data Team • 04/13/2020
The vulnerability described in CVE-2018-9543 represents a critical information disclosure flaw within the Android operating system's filesystem formatting utilities. This issue specifically affects the f2fs_format_utils.c component which is responsible for managing the Flash-Friendly File System (F2FS) formatting operations during factory reset processes. The vulnerability stems from a missing preprocessor definition that prevents proper data wiping during device factory resets, creating a persistent security risk that can be exploited without any user interaction or additional privileges.
The technical root cause of this vulnerability lies in the conditional compilation directive WITH_BLKDISCARD within the f2fs_format_utils.c file. When this directive is not properly defined, the system fails to execute the necessary block discard operations that would normally wipe the data partition during factory reset procedures. This condition creates a scenario where sensitive user data remains accessible on the storage medium even after a factory reset, effectively bypassing the intended security mechanism. The flaw operates at the filesystem level and demonstrates a clear failure in the secure deletion process that should occur during device provisioning.
The operational impact of this vulnerability extends beyond simple information disclosure, as it fundamentally undermines the security assumptions of device reset procedures. Attackers can exploit this weakness to recover sensitive data such as personal documents, application data, cryptographic keys, and other confidential information that should have been permanently removed during factory reset. The vulnerability is particularly concerning because it requires no additional privileges or user interaction for exploitation, making it accessible to any local attacker with basic system access. This characteristic aligns with attack patterns documented in the MITRE ATT&CK framework under the technique of credential access and data exfiltration. The vulnerability affects Android 9.0 and potentially other versions that utilize the same F2FS formatting utilities, creating a widespread security concern across numerous devices.
Mitigation strategies for this vulnerability primarily focus on implementing proper code fixes within the Android source code repositories. The recommended approach involves ensuring that the WITH_BLKDISCARD preprocessor directive is properly defined during compilation of the f2fs_format_utils.c component, which will enable the necessary block discard operations during factory reset. Organizations and device manufacturers should prioritize applying security patches that address this specific compilation issue and verify that factory reset procedures properly execute data wiping operations. Additionally, system administrators should implement monitoring solutions to detect anomalous data access patterns that might indicate exploitation attempts. The vulnerability's classification under CWE-200 (Information Exposure) and its operational characteristics align with ATT&CK techniques related to data breach and information gathering, emphasizing the need for comprehensive security measures. Regular security audits of filesystem utilities and proper code review processes should be implemented to prevent similar issues in future development cycles, ensuring that security mechanisms function as intended during critical system operations.