CVE-2016-9017 in MuJS
Summary
by MITRE
Artifex Software, Inc. MuJS before a5c747f1d40e8d6659a37a8d25f13fb5acf8e767 allows context-dependent attackers to obtain sensitive information by using the "opname in crafted JavaScript file" approach, related to an "Out-of-Bounds read" issue affecting the jsC_dumpfunction function in the jsdump.c component.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 09/29/2022
The vulnerability identified as CVE-2016-9017 affects Artifex Software, Inc. MuJS JavaScript engine version prior to a5c747f1d40e8d6659a37a8d25f13fb5acf8e767. This security flaw represents a critical information disclosure issue that arises from improper handling of JavaScript parsing operations within the engine's dump functionality. The vulnerability specifically manifests when processing crafted JavaScript files containing maliciously constructed "opname" operations, creating a scenario where attackers can extract sensitive data from memory locations that should remain protected.
The technical root cause of this vulnerability lies within the jsC_dumpfunction function located in the jsdump.c component of the MuJS engine. This function is responsible for dumping JavaScript function information for debugging and analysis purposes, but it fails to properly validate input parameters when processing opname operations. The flaw constitutes an out-of-bounds read condition that occurs when the engine attempts to access memory locations beyond the allocated bounds of an array or buffer. This type of vulnerability is classified under CWE-129 as "Improper Validation of Array Index" and specifically relates to improper bounds checking in memory access operations. The vulnerability enables attackers to manipulate the JavaScript engine's parsing behavior through carefully crafted input files that trigger the out-of-bounds memory access pattern.
The operational impact of CVE-2016-9017 extends beyond simple information disclosure, as it provides attackers with the ability to extract potentially sensitive data from the application's memory space. This includes but is not limited to stack contents, heap data, or other memory segments that may contain authentication tokens, cryptographic keys, or other confidential information. The context-dependent nature of this vulnerability means that exploitation requires specific conditions to be met, including the ability to influence the JavaScript execution environment and provide crafted input files that trigger the vulnerable code path. Attackers can leverage this vulnerability in web applications that utilize MuJS as their JavaScript engine, potentially leading to privilege escalation, credential theft, or further exploitation of the compromised system. The vulnerability aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: JavaScript' and T1552.001 for 'Unsecured Credentials' as it enables unauthorized access to sensitive information that could be used for additional attacks.
Mitigation strategies for CVE-2016-9017 primarily involve upgrading to a patched version of the MuJS JavaScript engine that addresses the out-of-bounds read condition in the jsC_dumpfunction implementation. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive timely updates. Additionally, input validation and sanitization measures should be strengthened at the application level to prevent malicious JavaScript files from reaching the vulnerable engine components. Security monitoring should include detection of unusual JavaScript parsing patterns and memory access behaviors that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper bounds checking in interpreted language engines and highlights the need for comprehensive security testing of parsing and dumping functionalities within JavaScript implementations. System administrators should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation attempts, while maintaining detailed logging of JavaScript engine activities for forensic analysis purposes.