CVE-2018-9498 in Android
Summary
by MITRE
In SkSampler::Fill of SkSampler.cpp, there is a possible out of bounds write due to an integer overflow. This could lead to remote code execution 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 ID: A-78354855
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Analysis
by VulDB Data Team • 03/29/2020
The vulnerability identified as CVE-2018-9498 represents a critical security flaw within the Android graphics rendering system, specifically in the SkSampler::Fill function of SkSampler.cpp. This issue manifests as a possible out of bounds write condition that stems from an integer overflow vulnerability, fundamentally compromising the integrity of the Android operating system's graphics processing capabilities. The flaw exists within the Skia graphics library component that Android utilizes for rendering operations, making it a core component of the system's visual processing pipeline.
The technical nature of this vulnerability involves an integer overflow that occurs during the processing of graphics data within the SkSampler class. When handling certain image data structures, the integer arithmetic used to calculate memory boundaries fails to properly validate input values, leading to an overflow condition. This overflow results in memory being written beyond the allocated buffer boundaries, creating a scenario where arbitrary memory locations can be overwritten. The vulnerability is particularly dangerous because it can be exploited to achieve remote code execution without requiring any additional privileges or user interaction beyond initial exploitation. The integer overflow occurs in a context where the application processes graphics data, making it accessible through various attack vectors including malicious image files or web content.
From an operational impact perspective, this vulnerability affects multiple Android versions including 7.0, 7.1.1, 7.1.2, 8.0, and 8.1, representing a significant portion of the Android ecosystem at the time of discovery. The remote code execution capability means that attackers can potentially compromise devices through malicious web content, image files, or other graphics-based attack vectors without requiring user interaction beyond visiting a compromised website or opening a malicious file. The vulnerability's classification as a remote code execution threat through a graphics processing component aligns with ATT&CK technique T1059.007 for command and scripting interpreter, and T1203 for exploitation for privilege escalation, as the initial compromise can lead to full system control. The flaw demonstrates a classic buffer overflow vulnerability pattern that can be exploited to execute arbitrary code, with the integer overflow creating the conditions necessary for memory corruption.
The exploitation of this vulnerability requires user interaction, typically through visiting a malicious website or opening a compromised file containing specially crafted graphics data. This interaction model makes the vulnerability particularly concerning as it can be delivered through common attack vectors such as phishing emails, malicious advertisements, or compromised websites. The integer overflow creates a predictable memory corruption pattern that can be leveraged by attackers to overwrite critical memory locations, potentially including return addresses or function pointers, enabling arbitrary code execution. This vulnerability directly maps to CWE-190, Integer Overflow or Wraparound, which specifically addresses integer arithmetic issues that can lead to memory corruption. The vulnerability's impact is amplified by the fact that it operates within the graphics processing pipeline, which is frequently accessed by applications and system components, making successful exploitation more likely.
Mitigation strategies for CVE-2018-9498 involve immediate patching of affected Android versions, as Google released security updates to address this specific vulnerability. Organizations should implement comprehensive monitoring for suspicious graphics-related activities and ensure all Android devices are updated to the latest security patches. Network-level protections can include filtering of suspicious image files and web content, while application-level defenses should include input validation and memory protection mechanisms. The vulnerability highlights the importance of secure coding practices in graphics processing components and demonstrates the critical need for regular security assessments of system libraries. Additionally, implementing sandboxing mechanisms and privilege separation can help limit the potential impact if exploitation occurs, aligning with defense-in-depth strategies recommended by various cybersecurity frameworks including NIST SP 800-53 and ISO 27001 standards.