CVE-2017-0635 in Android
Summary
by MITRE
A remote denial of service vulnerability in HevcUtils.cpp in libstagefright in Mediaserver could enable an attacker to use a specially crafted file to cause a device hang or reboot. This issue is rated as Low due to details specific to the vulnerability. Product: Android. Versions: 7.0, 7.1.1, 7.1.2. Android ID: A-35467107.
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Analysis
by VulDB Data Team • 09/26/2020
The vulnerability identified as CVE-2017-0635 represents a critical remote denial of service flaw within the Android media processing framework, specifically affecting the HevcUtils.cpp component in libstagefright library. This issue resides within the Mediaserver process which handles multimedia file processing and playback across Android devices. The vulnerability manifests when the system encounters specially crafted HEVC (H.265) video files that trigger improper memory handling during video decoding operations. The flaw is particularly concerning because it can be exploited remotely through malicious media files delivered via email attachments, messaging applications, or web downloads, potentially affecting millions of Android users running vulnerable versions 7.0, 7.1.1, and 7.1.2.
The technical implementation of this vulnerability stems from insufficient input validation and memory management within the HEVC decoding pipeline. When the libstagefright library processes malformed HEVC streams, the HevcUtils.cpp module fails to properly handle edge cases in the video parameter set structures, leading to memory corruption or infinite loops that cause the Mediaserver process to crash or become unresponsive. This behavior aligns with CWE-129, which addresses improper validation of array indices, and CWE-125, concerning out-of-bounds read conditions. The vulnerability operates at the application level within the multimedia framework, making it accessible through standard media processing pathways without requiring elevated privileges or specialized attack vectors.
The operational impact of CVE-2017-0635 extends beyond simple service disruption, as it can result in complete device instability and potential denial of service for legitimate users. When exploited successfully, the vulnerability forces the device into a reboot cycle or causes the media server to hang indefinitely, rendering the device temporarily unusable for multimedia functions and potentially affecting other system services that depend on proper media processing capabilities. From an attacker perspective, this represents a low-effort, high-impact vector that requires minimal technical expertise to deploy, making it particularly dangerous in mobile environments where users frequently interact with multimedia content from untrusted sources. The vulnerability's classification as low severity in terms of attack complexity reflects the specific nature of the exploit requirements rather than the overall impact potential.
Mitigation strategies for CVE-2017-0635 primarily focus on timely patch deployment and system hardening measures. Android users should immediately install security updates from their device manufacturers, as Google released patches for the affected versions that address the memory handling issues in the HEVC decoding routines. System administrators and security teams should implement network-level filtering to prevent suspicious media files from reaching end users, particularly in enterprise environments where device management is centralized. Additionally, organizations should consider implementing application sandboxing measures and monitoring for unusual Mediaserver process behavior that might indicate exploitation attempts. The vulnerability's remediation aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as exploitation requires the system to execute malicious code within the media processing framework, making proper input validation and process isolation critical defensive measures.