CVE-2018-16764 in WAVM
Summary
by MITRE
In WAVM through 2018-07-26, a crafted file sent to the WebAssembly Virtual Machine may cause a denial of service (application crash) or possibly have unspecified other impact because of an IR::FunctionValidationContext::catch_all heap-based buffer over-read.
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Analysis
by VulDB Data Team • 05/07/2023
The vulnerability identified as CVE-2018-16764 affects WAVM, a WebAssembly virtual machine implementation, specifically up to the version released on 2018-07-26. This issue represents a critical security flaw that arises from improper input validation within the IR::FunctionValidationContext::catch_all function. The vulnerability manifests as a heap-based buffer over-read, which occurs when the virtual machine processes maliciously crafted WebAssembly files that contain malformed or specially constructed data structures. Such buffer over-read conditions typically arise when program code attempts to read memory locations beyond the allocated buffer boundaries, potentially leading to unpredictable behavior and system instability.
The technical exploitation of this vulnerability involves sending a specially crafted WebAssembly file to the WAVM runtime environment, which then processes the file through its intermediate representation validation mechanisms. During this validation process, the IR::FunctionValidationContext::catch_all function fails to properly bounds-check memory accesses, allowing an attacker to trigger a heap-based buffer over-read condition. This flaw falls under the Common Weakness Enumeration category CWE-125, which specifically addresses out-of-bounds read vulnerabilities, and represents a variant of memory safety issues that have been extensively documented in the software security community. The vulnerability can potentially be leveraged by adversaries to cause application crashes or, in more sophisticated scenarios, may enable further exploitation techniques that could lead to arbitrary code execution or information disclosure.
From an operational perspective, this vulnerability poses significant risks to systems that rely on WAVM for WebAssembly execution, particularly in environments where untrusted WebAssembly content is processed. The denial of service impact can disrupt legitimate operations by causing application crashes, while the unspecified additional impacts suggest potential for more severe consequences including privilege escalation or data corruption. The vulnerability is particularly concerning because WebAssembly is increasingly used in web browsers, server-side applications, and sandboxed environments where such flaws can be exploited to compromise system integrity. Attackers could potentially construct malicious WebAssembly modules that, when executed, trigger the buffer over-read condition and cause system instability.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected WAVM installations to the latest secure versions that contain fixes for the buffer over-read issue. Organizations should implement strict input validation and sanitization measures when processing WebAssembly content, particularly in environments where untrusted code execution is possible. Network segmentation and access controls can help limit the potential impact of exploitation attempts, while monitoring systems should be configured to detect unusual application behavior that might indicate exploitation attempts. Additionally, security teams should consider implementing runtime protection mechanisms such as address space layout randomization and stack canaries to make exploitation more difficult. The ATT&CK framework categorizes this type of vulnerability under the 'Memory Corruption' tactic, with potential techniques including 'Exploitation for Privilege Escalation' and 'Denial of Service' depending on the specific exploitation scenario. Regular security assessments and vulnerability scanning should be conducted to identify similar memory safety issues in other components of the WebAssembly ecosystem.