CVE-2019-1986 in Android
Summary
by MITRE
In SkSwizzler::onSetSampleX of SkSwizzler.cpp, there is a possible out of bounds write due to a missing bounds check. This could lead to remote escalation of privilege in system_server with no additional execution privileges needed. User interaction is needed for exploitation. Product: Android. Versions: Android-9. Android ID: A-117838472.
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Analysis
by VulDB Data Team • 07/26/2023
The vulnerability identified as CVE-2019-1986 resides within the SkSwizzler::onSetSampleX function of the SkSwizzler.cpp file within the Android operating system. This represents a critical out-of-bounds write flaw that stems from the absence of proper bounds checking mechanisms. The issue manifests in the graphics rendering subsystem where the system processes sample data for image manipulation operations. The vulnerability is particularly concerning as it operates within the system_server process, which holds elevated privileges and serves as a core component of Android's security architecture. When exploited, this flaw could enable remote privilege escalation, allowing an attacker to gain system-level access without requiring any additional execution privileges. The vulnerability affects Android 9.0 (Pie) and potentially other versions within the Android 9.0 release cycle, with the Android ID A-117838472 documenting this specific weakness.
The technical nature of this vulnerability aligns with CWE-129, which describes improper validation of array index values, and more specifically relates to CWE-787, which addresses out-of-bounds write conditions. The flaw occurs when the SkSwizzler component processes image sample data without verifying that the provided indices remain within acceptable bounds. This allows an attacker to craft malicious input that can overwrite adjacent memory locations, potentially corrupting critical system data structures or executing arbitrary code. The out-of-bounds write vulnerability is particularly dangerous because it can be leveraged to overwrite function pointers, return addresses, or other critical memory regions that control program execution flow. The exploitation requires user interaction, typically through malicious media files or web content that triggers the vulnerable graphics processing code path.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with a pathway to compromise the entire Android system. When the system_server process executes with elevated privileges, any successful exploitation can result in complete system compromise, allowing attackers to access all user data, install malicious applications, modify system files, and potentially maintain persistent access. The vulnerability's classification as a remote escalation vector means that attackers do not need physical access to the device or local execution privileges to exploit this weakness. This makes it particularly dangerous in scenarios where users might encounter malicious content through email attachments, web browsing, or downloaded media files. The security implications are further amplified by the fact that system_server operates with extensive system privileges, making it a prime target for attackers seeking maximum system control.
Mitigation strategies for CVE-2019-1986 should focus on immediate patch deployment through Android security updates, as Google released patches for this vulnerability in their regular security bulletins. Organizations should prioritize updating all affected Android 9.0 devices to the latest security patches available through the standard update channels. Additional defensive measures include implementing network-level filtering to block suspicious content and deploying mobile device management solutions that can enforce security policies. The vulnerability's exploitation requires user interaction, so security awareness training for end users becomes critical in preventing successful attacks. From an ATT&CK framework perspective, this vulnerability maps to T1068, which covers 'Exploitation for Privilege Escalation', and T1059, which covers 'Command and Scripting Interpreter'. Network administrators should monitor for unusual outbound connections or file modifications that might indicate exploitation attempts, while system administrators should ensure that all Android devices are kept up to date with security patches. The vulnerability demonstrates the importance of comprehensive input validation in system-level components and highlights the need for rigorous security testing of graphics rendering subsystems that operate with elevated privileges.