CVE-2020-36330 in iOS
Summary
by MITRE • 05/21/2021
A flaw was found in libwebp in versions before 1.0.1. An out-of-bounds read was found in function ChunkVerifyAndAssign. The highest threat from this vulnerability is to data confidentiality and to the service availability.
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Analysis
by VulDB Data Team • 07/27/2021
The vulnerability identified as CVE-2020-36330 represents a critical out-of-bounds read flaw within the libwebp library version 1.0.1 and earlier. This issue manifests in the ChunkVerifyAndAssign function where improper input validation leads to memory access violations that can be exploited by malicious actors. The libwebp library serves as a fundamental component for webp image format processing across numerous applications and platforms, making this vulnerability particularly dangerous due to its widespread adoption and potential for exploitation.
The technical nature of this vulnerability stems from insufficient bounds checking during the verification process of webp image chunks. When processing malformed webp files, the ChunkVerifyAndAssign function fails to properly validate the boundaries of memory allocations, allowing attackers to craft specially crafted image files that trigger memory access beyond allocated buffers. This out-of-bounds read condition can result in information disclosure, as sensitive data from adjacent memory locations may be exposed to unauthorized access. The vulnerability operates at the memory management level and can be classified under CWE-129 as "Improper Validation of Array Index" and CWE-125 as "Out-of-Bounds Read" within the Common Weakness Enumeration framework.
The operational impact of this vulnerability extends beyond simple data confidentiality concerns to encompass service availability risks that can lead to denial of service conditions. Attackers can exploit this flaw by submitting malicious webp images to applications that utilize libwebp for image processing, potentially causing application crashes or system instability. The threat model aligns with ATT&CK technique T1203 as "Exploitation for Client Execution" and T1499 as "Endpoint Denial of Service" where the vulnerability can be leveraged to disrupt service availability. Systems that process user-uploaded webp images, web servers handling image content, and applications with webp image processing capabilities are particularly vulnerable to this attack vector.
Mitigation strategies should prioritize immediate patching of libwebp installations to version 1.0.1 or later where the vulnerability has been addressed through proper bounds checking implementation. Organizations should implement input validation mechanisms that reject malformed webp files before they reach the vulnerable library functions, utilizing sandboxing techniques and strict content filtering. Network segmentation and application firewalls can provide additional protection layers while monitoring for suspicious image file processing activities. Regular security assessments of third-party libraries and maintaining up-to-date vulnerability databases will help prevent similar issues from affecting system security posture. The vulnerability demonstrates the critical importance of proper memory management in image processing libraries and highlights the need for comprehensive security testing of commonly used open source components.