CVE-2018-9372 in Android
Summary
by MITRE • 11/19/2024
In cmd_flash_mmc_sparse_img of dl_commands.c, there is a possible out of bounds write due to a missing bounds check. This could lead to a local escalation of privilege in the bootloader with no additional execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 07/03/2025
The vulnerability identified as CVE-2018-9372 represents a critical out-of-bounds write flaw within the bootloader component of certain embedded systems, specifically within the cmd_flash_mmc_sparse_img function located in dl_commands.c. This type of vulnerability falls under the CWE-787 category of out-of-bounds write conditions, where insufficient input validation allows malicious data to overwrite adjacent memory locations. The flaw exists in the sparse image flashing functionality that handles mmc (multi-media card) storage operations during the device boot process. The vulnerability is particularly concerning because it operates within the bootloader context, which typically runs with the highest privilege level and has direct access to critical system components and memory spaces. Attackers can exploit this vulnerability without requiring any user interaction or additional execution privileges, making it a particularly dangerous local privilege escalation vector.
The technical implementation of this vulnerability stems from the absence of proper bounds checking when processing sparse image data structures during flash operations on mmc storage devices. When the bootloader processes sparse images, it reads metadata about the image structure including size information and data block locations. However, the cmd_flash_mmc_sparse_img function fails to validate that the calculated memory addresses for writing data blocks remain within the allocated buffer boundaries. This allows an attacker to craft a malicious sparse image that, when processed by the bootloader, causes data to be written beyond the intended memory allocation. The lack of input validation creates a predictable overflow condition that can overwrite adjacent memory locations including critical control structures, function pointers, or other sensitive data within the bootloader's memory space.
The operational impact of CVE-2018-9372 extends beyond simple memory corruption as it enables local privilege escalation directly within the bootloader environment where the vulnerability resides. Since the bootloader typically operates with the highest system privileges and direct hardware access, successful exploitation can result in complete system compromise without requiring additional attack vectors or user interaction. This vulnerability specifically targets the pre-boot execution environment where the device's firmware and operating system are initialized, making it particularly dangerous as it can potentially allow attackers to modify critical boot components, install persistent backdoors, or gain access to encrypted storage volumes. The vulnerability's exploitation does not require any user interaction, meaning that any device that processes the malicious sparse image during normal boot operations becomes immediately compromised.
Mitigation strategies for CVE-2018-9372 should focus on implementing comprehensive input validation and bounds checking within the bootloader's sparse image processing functions. The primary fix involves adding proper validation of all memory access operations within cmd_flash_mmc_sparse_img to ensure that calculated addresses remain within the intended buffer boundaries. This includes implementing strict size checks on sparse image metadata, verifying that data block locations do not exceed allocated memory space, and ensuring that all memory operations are properly bounded. System vendors should also consider implementing additional security measures such as code integrity verification, secure boot mechanisms, and runtime memory protection features that can detect and prevent unauthorized memory modifications. From an ATT&CK perspective, this vulnerability maps to privilege escalation techniques within the boot process, specifically targeting the T1059.001 command and scripting language category for executing malicious code through bootloader modifications, and T1542.001 for boot or logon initialization scripts that could be leveraged for persistence. Organizations should also implement firmware integrity monitoring solutions and regularly update bootloader components to address similar vulnerabilities that may exist in other system components.