CVE-2018-9491 in Android
Summary
by MITRE
In AMediaCodecCryptoInfo_new of NdkMediaCodec.cpp, there is a possible out-of-bounds write due to an integer overflow. This could lead to remote code execution in external apps 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-9.0 Android ID: A-111603051
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Analysis
by VulDB Data Team • 03/29/2020
The vulnerability described in CVE-2018-9491 represents a critical integer overflow flaw within the Android media framework's native code implementation. This issue exists in the AMediaCodecCryptoInfo_new function located in NdkMediaCodec.cpp, which serves as a crucial component for handling cryptographic operations within the Android media pipeline. The vulnerability stems from improper validation of input parameters during the construction of media codec crypto information structures, creating a scenario where an attacker can manipulate integer values to cause unexpected behavior in memory allocation and data handling processes.
The technical exploitation of this vulnerability involves a specific integer overflow condition that occurs when processing cryptographic information for media codecs. When an application processes media content with specific cryptographic parameters, the integer overflow can cause the system to allocate insufficient memory or write data beyond intended boundaries. This out-of-bounds write condition manifests as a potential code execution vector that can be leveraged by malicious actors. The flaw is particularly dangerous because it operates at the native code level within the Android framework, allowing for direct manipulation of memory structures without requiring elevated privileges or additional attack vectors beyond the initial exploitation trigger.
The operational impact of this vulnerability extends across multiple Android versions including 7.0, 7.1.1, 7.1.2, 8.0, 8.1, and 9.0, indicating a widespread exposure affecting a significant portion of the Android ecosystem. The requirement for user interaction means that exploitation typically occurs through social engineering or malicious media content delivery, where a user must initiate interaction with compromised media files or applications. This attack vector aligns with the ATT&CK framework's technique T1203, which involves exploiting software vulnerabilities to gain code execution. The vulnerability's classification under CWE-190, Integer Overflow or Wraparound, demonstrates the fundamental nature of the flaw in how integer arithmetic is handled within the cryptographic processing pipeline.
The implications of this vulnerability are particularly severe for Android applications that utilize the native media codec APIs for processing encrypted media content. Attackers can craft specially formatted media files or manipulate cryptographic parameters to trigger the integer overflow, potentially leading to arbitrary code execution within the context of the affected application. The lack of additional execution privileges required for exploitation makes this vulnerability particularly attractive to threat actors seeking to compromise Android devices. Security researchers have noted that the vulnerability's exploitation can result in complete system compromise, as the out-of-bounds write can be used to overwrite critical memory structures or inject malicious code into the application's execution context.
Mitigation strategies for CVE-2018-9491 primarily focus on applying the relevant security patches provided by Google through the Android security bulletins. Organizations and users should prioritize immediate installation of the patched Android versions that address this specific integer overflow condition. The recommended approach involves monitoring Android security updates and applying them promptly to all affected devices. Additionally, implementing network-level controls and content filtering can help reduce the risk of exploitation through malicious media content delivery. Security teams should also consider deploying mobile device management solutions that can enforce security policies and ensure timely patch deployment across enterprise environments. The vulnerability's classification as a remote code execution flaw emphasizes the importance of maintaining up-to-date security measures and implementing defense-in-depth strategies to protect against similar integer overflow vulnerabilities in other components of the Android framework.