CVE-2021-46331 in Moddable
Summary
by MITRE • 01/21/2022
Moddable SDK v11.5.0 was discovered to contain a SEGV vulnerability via xs/sources/xsProxy.c in fxProxyGetPrototype.
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Analysis
by VulDB Data Team • 01/27/2023
The vulnerability identified as CVE-2021-46331 represents a critical segmentation fault condition within the Moddable SDK version 11.5.0, specifically manifesting in the xsProxy.c source file at the fxProxyGetPrototype function. This issue constitutes a memory access violation that can lead to arbitrary code execution and system instability. The flaw exists within the JavaScript engine's proxy handling mechanism, which is fundamental to the SDK's object model implementation and runtime behavior. When the fxProxyGetPrototype function processes certain proxy objects, it fails to properly validate input parameters, creating a path for attackers to trigger a segmentation fault through malformed proxy configurations.
The technical root cause of this vulnerability lies in inadequate input validation and memory management within the proxy prototype retrieval process. The function does not properly check the validity of proxy objects or their associated prototype chains before attempting to access memory locations. This type of vulnerability falls under the CWE-125 vulnerability category, which describes out-of-bounds read conditions that can result in information disclosure, system crashes, or potential code execution. The flaw demonstrates characteristics of a buffer over-read scenario where the proxy handling code attempts to access memory beyond the allocated bounds of proxy objects, leading to system crashes or exploitable conditions.
From an operational impact perspective, this vulnerability poses significant risks to applications built using the Moddable SDK, particularly those deployed in embedded systems or IoT environments where the SDK is used for device management and scripting. The segmentation fault can cause complete application crashes, potentially leading to denial of service conditions that may affect critical device functionality. Attackers could exploit this vulnerability by crafting malicious proxy objects that, when processed by the fxProxyGetPrototype function, trigger the segmentation fault and potentially allow for privilege escalation or arbitrary code execution. The vulnerability is particularly concerning in environments where the SDK handles untrusted input data, such as user-generated content or network communications.
The mitigation strategy for CVE-2021-46331 requires immediate patching of the Moddable SDK to version 11.5.1 or later, which contains the necessary fixes for the proxy handling mechanism. Organizations should also implement input validation measures to prevent malformed proxy objects from reaching the vulnerable function, particularly in applications that process external data. Security monitoring should be enhanced to detect unusual patterns in proxy object creation and usage that may indicate exploitation attempts. Additionally, system administrators should consider implementing runtime protections such as address space layout randomization and stack canaries to reduce the exploitability of similar memory corruption vulnerabilities. The vulnerability aligns with ATT&CK technique T1059.007 for script-based execution and T1555.001 for credentials from password storage components, as it could potentially be leveraged to gain unauthorized access to systems where the SDK is deployed.