CVE-2017-13285 in Android
Summary
by MITRE
In SvoxSsmlParser and startElement of svox_ssml_parser.cpp, there is a possible out of bounds write due to an uninitialized buffer. This could lead to remote code execution in an unprivileged process with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android. Versions: 6.0, 6.0.1, 7.0, 7.1.1, 7.1.2, 8.0, 8.1. Android ID: A-69177126.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 01/21/2020
The vulnerability identified as CVE-2017-13285 represents a critical out-of-bounds write flaw within the Svox Speech Synthesis Markup Language parser component of Android operating systems. This vulnerability exists in the svox_ssml_parser.cpp file within the SvoxSsmlParser class and specifically affects the startElement function where an uninitialized buffer is accessed. The flaw stems from improper memory management practices where buffer boundaries are not properly validated before write operations, creating a scenario where malicious input can cause arbitrary memory corruption. The vulnerability is classified under CWE-121 as a stack-based buffer overflow condition, though the specific implementation involves uninitialized memory access rather than traditional buffer overflow mechanisms. This type of vulnerability is particularly dangerous because it can be exploited remotely without requiring user interaction, making it a significant threat vector for attackers seeking to compromise Android devices.
The technical implementation of this vulnerability occurs when the Svox speech synthesis parser processes malformed SSML (Speech Synthesis Markup Language) content that triggers an uninitialized buffer write operation. The parser fails to properly initialize memory buffers before use, allowing attackers to craft specially formatted SSML documents that can overwrite adjacent memory locations. When the startElement function processes these malicious inputs, the uninitialized buffer can be written beyond its allocated boundaries, potentially overwriting critical program data or execution pointers. This memory corruption can be leveraged to redirect program execution flow, leading to remote code execution capabilities. The vulnerability affects multiple Android versions including 6.0, 6.0.1, 7.0, 7.1.1, 7.1.2, 8.0, and 8.1, indicating a widespread impact across the Android ecosystem and suggesting that the root cause was present in the core speech synthesis components.
The operational impact of CVE-2017-13285 extends beyond simple code execution, as it can be exploited through various attack vectors that do not require user interaction. An attacker can deliver malicious SSML content through web applications, SMS messages, or other communication channels that utilize the Android speech synthesis framework. This remote exploitation capability aligns with ATT&CK technique T1203, where adversaries use malicious payloads to gain code execution in target systems. The vulnerability's impact is particularly severe because it operates within an unprivileged process, meaning attackers can achieve code execution without requiring elevated privileges or additional attack vectors. The affected Svox parser is commonly used in Android's accessibility features and speech synthesis services, making it a persistent threat vector across numerous legitimate applications and system components. This vulnerability essentially provides a backdoor entry point that can be exploited by attackers to execute arbitrary code, potentially leading to complete system compromise, data exfiltration, or further lateral movement within network environments.
Mitigation strategies for CVE-2017-13285 primarily focus on applying security patches and updates provided by Google for affected Android versions. Organizations and device users should immediately install the relevant security updates from their device manufacturers and Google's Android security bulletins. The vulnerability can also be addressed through network-level controls that filter or block SSML content from untrusted sources, though this approach is less effective than patching the underlying implementation. System administrators should consider implementing additional security monitoring to detect anomalous speech synthesis activity that might indicate exploitation attempts. The fix typically involves proper buffer initialization and boundary checking within the Svox parser implementation, ensuring that all memory allocations are properly validated before write operations occur. Security teams should also conduct vulnerability assessments to identify systems running affected Android versions and prioritize patch deployment based on risk exposure. The remediation process should include verification that the patched implementations correctly handle malformed SSML inputs and that no similar uninitialized buffer issues exist in related components of the Android speech synthesis framework.