CVE-2018-9347 in Android
Summary
by MITRE
In function SMF_ParseMetaEvent of file eas_smf.c there is incorrect input validation causing an infinite loop. This could lead to a remote temporary DoS with no additional execution privileges needed. User interaction is needed for exploitation. Product: Android. Versions: Android-7.0 Android-7.1.1 Android-7.1.2 Android-8.0 Android-8.1 Android-9. Android ID: A-68664359
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Analysis
by VulDB Data Team • 04/13/2020
The vulnerability described in CVE-2018-9347 represents a critical input validation flaw within the Android media processing framework that specifically affects the SMF_ParseMetaEvent function in the eas_smf.c file. This issue stems from inadequate boundary checking and validation mechanisms that fail to properly handle malformed input data during the parsing of Standard MIDI File (SMF) metadata events. The flaw exists within the Android media library implementation where the parsing logic does not sufficiently validate the length and structure of incoming MIDI metadata, creating a condition where malformed data can cause the parser to enter an infinite loop state.
The technical implementation of this vulnerability manifests when the SMF_ParseMetaEvent function processes specially crafted MIDI files that contain malformed metadata events with incorrect length fields or invalid data structures. The function fails to validate that the expected data length matches the actual available data, leading to a scenario where loop conditions become perpetually true due to improper boundary calculations. This allows an attacker to construct a malicious MIDI file that, when processed by Android's media framework, triggers the infinite loop condition without requiring any special privileges or execution rights. The vulnerability specifically impacts Android versions ranging from 7.0 through 9.0, indicating a widespread issue affecting multiple major Android releases.
The operational impact of this vulnerability creates a remote temporary denial of service condition that can be exploited through user interaction, typically via the installation or opening of a malicious MIDI file. The infinite loop consumes system resources and effectively freezes the media processing thread, making the affected Android device temporarily unusable for media-related operations. This vulnerability falls under CWE-835, which specifically addresses the issue of infinite loops or other looping constructs that do not have a valid exit condition, making it a classic example of a resource exhaustion vulnerability. The attack vector requires minimal privileges and can be executed remotely through various delivery mechanisms such as email attachments, web downloads, or file sharing platforms.
From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1059.007, which involves the use of scripting languages for execution, as the infinite loop can be triggered through the standard Android media processing pipeline. The vulnerability's exploitation requires only that a user interact with the malicious file, making it particularly dangerous in social engineering contexts where users might be tricked into opening seemingly legitimate media files. Organizations and users should consider this vulnerability as part of a broader threat landscape where attackers may leverage such resource exhaustion flaws to disrupt services or create temporary system unavailability. The remediation approach should focus on implementing proper input validation and boundary checking mechanisms, including the addition of explicit length validation checks and timeout mechanisms to prevent infinite loop conditions.
The fix for this vulnerability involves strengthening the input validation logic within the SMF_ParseMetaEvent function to ensure that all data structures are properly validated before processing, implementing appropriate bounds checking, and adding timeout mechanisms to prevent indefinite loop execution. Android security patches addressing this vulnerability would typically include modifications to the eas_smf.c file to ensure that metadata event lengths are validated against available data, preventing the conditions that lead to infinite loop execution. The vulnerability demonstrates the importance of proper input validation in multimedia processing libraries and highlights the need for robust boundary checking mechanisms in all file format parsers to prevent similar issues in other media processing components.