CVE-2018-9340 in Android
Summary
by MITRE • 11/19/2024
In ResStringPool::setTo of ResourceTypes.cpp, it's possible for an attacker to control the value of mStringPoolSize to be out of bounds, causing information disclosure.
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Analysis
by VulDB Data Team • 11/19/2024
The vulnerability identified as CVE-2018-9340 resides within the Android framework's resource handling mechanisms, specifically in the ResStringPool::setTo function located in ResourceTypes.cpp. This flaw represents a classic out-of-bounds memory access issue that can be exploited through careful manipulation of input data during resource parsing operations. The vulnerability occurs when the mStringPoolSize parameter is manipulated by an attacker to exceed valid memory boundaries, creating a scenario where the application attempts to access memory locations outside the intended allocation. Such manipulation typically occurs during the processing of Android resource files, particularly when parsing binary xml files or other resource containers that utilize string pools for efficient data storage and retrieval. The underlying issue stems from insufficient bounds checking mechanisms that should validate the size parameter against acceptable memory constraints before proceeding with memory allocation operations.
The technical execution of this vulnerability involves an attacker constructing malicious resource data that contains an oversized string pool size value. When the Android framework attempts to process this malformed data, the ResStringPool::setTo function fails to properly validate the mStringPoolSize parameter, allowing the value to exceed the legitimate memory boundaries. This condition can trigger various memory corruption behaviors including information disclosure, where adjacent memory contents become accessible to the attacker through the out-of-bounds read operations. The vulnerability is particularly concerning because it operates at a low level within the Android framework's resource management system, making it difficult to detect and potentially exploitable through various attack vectors including malicious applications or compromised resource files. The flaw can be categorized under CWE-129 as "Improper Validation of Array Index" and also relates to CWE-787 as "Out-of-bounds Write" when considering the potential for memory corruption.
The operational impact of CVE-2018-9340 extends beyond simple information disclosure, potentially enabling more sophisticated attacks depending on the execution context and system configuration. When exploited successfully, this vulnerability can allow attackers to extract sensitive information from memory locations adjacent to the string pool, potentially including cryptographic keys, user credentials, or other confidential data stored in memory. The attack surface includes any Android application or service that processes external resource files, particularly those involving binary xml parsing or resource management operations. This vulnerability is particularly dangerous in environments where Android applications process untrusted input or when resource files are downloaded from external sources, as these scenarios provide the ideal conditions for exploitation. The vulnerability affects multiple Android versions and can be leveraged by attackers to gain insights into the system's memory layout, potentially enabling further exploitation techniques such as heap spraying or bypassing memory protection mechanisms.
Mitigation strategies for CVE-2018-9340 should focus on implementing robust input validation and bounds checking mechanisms within the resource processing pipeline. Android security updates and patches typically address this vulnerability by introducing proper validation of the mStringPoolSize parameter before memory allocation occurs, ensuring that all size values fall within acceptable ranges. Organizations should prioritize applying the latest security patches from Google and maintain comprehensive monitoring of resource processing operations within their Android applications. Additional defensive measures include implementing strict input sanitization for all external resource files, utilizing sandboxing mechanisms to isolate resource processing operations, and employing memory protection techniques such as address space layout randomization and stack canaries. The vulnerability demonstrates the importance of proper bounds checking in memory management operations and aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell" and T1068 for "Exploitation for Privilege Escalation" when considering potential exploitation chains that could leverage information disclosure for further system compromise. Security teams should also consider implementing automated scanning tools that can detect malformed resource files and monitor for unusual memory access patterns that may indicate exploitation attempts.