CVE-2018-17292 in WAVM
Summary
by MITRE
An issue was discovered in WAVM before 2018-09-16. The loadModule function in Include/Inline/CLI.h lacks checking of the file length before a file magic comparison, allowing attackers to cause a Denial of Service (application crash caused by out-of-bounds read) by crafting a file that has fewer than 4 bytes.
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Analysis
by VulDB Data Team • 05/17/2023
The vulnerability identified as CVE-2018-17292 resides within the WAVM (WebAssembly Virtual Machine) project, specifically affecting versions prior to the September 16, 2018 release. This issue demonstrates a classic buffer over-read condition that occurs during the module loading process, highlighting a critical flaw in input validation mechanisms. The vulnerability is particularly concerning as it can be exploited to cause application crashes and potentially lead to more severe security implications through denial of service attacks against systems that rely on WAVM for WebAssembly execution.
The technical flaw manifests in the loadModule function located within the Include/Inline/CLI.h file of the WAVM codebase. This function performs a file magic comparison without first validating that the input file contains sufficient bytes to support the comparison operation. The absence of proper bounds checking means that when an attacker crafts a malicious file containing fewer than four bytes, the application attempts to read beyond the valid file boundaries during the magic number verification process. This out-of-bounds read condition results in unpredictable memory access patterns that ultimately cause the application to crash, effectively creating a denial of service scenario.
From an operational perspective, this vulnerability presents significant risks to systems that utilize WAVM for executing WebAssembly modules, particularly in environments where untrusted input is processed. The attack vector is relatively simple to implement as it requires only the creation of a malformed file with insufficient content, making it accessible to attackers with minimal technical expertise. The impact extends beyond mere service disruption as such vulnerabilities can be leveraged as part of broader attack chains, potentially enabling more sophisticated exploitation techniques. Organizations relying on WAVM for WebAssembly processing should consider this vulnerability as a critical threat that could compromise system availability and stability.
The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and represents a specific instance of insufficient input validation that leads to memory safety issues. From an ATT&CK framework perspective, this weakness maps to T1499.004, which covers the use of denial of service techniques through resource exhaustion or application crashes, and potentially T1059.001 for command and scripting language usage in crafting malicious payloads. The vulnerability demonstrates how seemingly minor oversights in input validation can create significant security risks, particularly in systems that process external data streams. Remediation efforts should focus on implementing proper bounds checking mechanisms that validate file size requirements before attempting any binary parsing operations, ensuring that all input processing operations include comprehensive validation to prevent out-of-bounds memory access patterns.