CVE-2018-11278 in Android
Summary
by MITRE
In all android releases(Android for MSM, Firefox OS for MSM, QRD Android) from CAF using the linux kernel, Venus HW searches for start code when decoding input bit stream buffers. If start code is not found in entire buffer, there is over-fetch beyond allocation length. This leads to page fault.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 05/16/2023
The vulnerability identified as CVE-2018-11278 represents a critical memory safety issue affecting multiple Android variants including MSM-based systems, Firefox OS for MSM, and QRD Android platforms. This flaw exists within the Linux kernel implementation of the Venus hardware video decoder component, which is responsible for processing multimedia content on these devices. The vulnerability stems from inadequate input validation during the video decoding process, specifically when the Venus hardware component searches for start codes within input bitstream buffers.
The technical flaw manifests when the Venus hardware decoder attempts to locate start codes within video data buffers to identify frame boundaries for decoding operations. When the decoder fails to find a valid start code throughout the entire buffer, the system exhibits improper memory handling behavior that results in an over-fetch condition. This over-fetch occurs beyond the allocated buffer boundaries, causing the kernel to attempt memory access beyond its intended allocation limits. The consequence of this memory violation is a page fault exception that can potentially crash the system or provide an avenue for further exploitation.
This vulnerability operates at the intersection of hardware and software components within the Android ecosystem, specifically targeting the kernel-level video decoding subsystem. The issue demonstrates a classic buffer over-read condition that can be exploited to cause system instability or potentially enable privilege escalation attacks. The impact is particularly concerning given that these affected platforms include various mobile devices and embedded systems where the Venus hardware decoder is actively utilized for multimedia processing. The vulnerability affects multiple generations of Android releases, indicating a widespread exposure across different device manufacturers and hardware configurations.
The operational impact of this vulnerability extends beyond simple system crashes, as it represents a potential pathway for attackers to exploit memory corruption issues within the kernel space. The over-fetch behavior can lead to information disclosure through memory leaks, or potentially enable more sophisticated attacks such as code execution or privilege escalation. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving memory corruption exploits and kernel-level privilege escalation. The weakness maps to CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write vulnerabilities. Security researchers have noted that such memory safety issues in hardware acceleration components represent particularly dangerous attack vectors due to their potential for system-level compromise.
Mitigation strategies for CVE-2018-11278 require immediate patching of affected kernel versions and implementation of proper buffer boundary checking mechanisms within the Venus hardware decoder. Device manufacturers should prioritize updating firmware to address the over-fetch condition and ensure that input validation routines properly handle cases where start codes are not found within allocated buffers. Additional protective measures include implementing memory protection mechanisms such as stack canaries, address space layout randomization, and kernel memory protection features to limit the potential impact of exploitation attempts. Organizations should also conduct thorough security assessments of their Android-based systems to identify other potential memory safety vulnerabilities within hardware acceleration components and ensure proper input validation across all multimedia processing pathways.