CVE-2019-1010171 in Jsish
Summary
by MITRE
Jsish 2.4.83 2.0483 is affected by: Nullpointer dereference. The impact is: denial of service. The component is: function jsi_DumpFunctions (jsiEval.c:567). The attack vector is: executing crafted javascript code. The fixed version is: 2.4.84.
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Analysis
by VulDB Data Team • 07/09/2020
The vulnerability identified as CVE-2019-1010171 affects the Jsish JavaScript interpreter version 2.4.83 and earlier, specifically within the jsi_DumpFunctions function located in jsiEval.c at line 567. This nullpointer dereference flaw represents a classic denial of service vulnerability that can be exploited through the execution of crafted javascript code. The Jsish interpreter is a lightweight javascript engine designed for embedded systems and command-line usage, making it susceptible to exploitation in environments where javascript execution is permitted. The vulnerability occurs when the interpreter processes certain javascript constructs that trigger the dump functions mechanism, leading to an attempt to dereference a null pointer during function analysis operations.
The technical implementation of this vulnerability stems from inadequate input validation within the jsi_DumpFunctions routine, which fails to properly check for null pointer conditions before attempting to access function metadata structures. When malicious javascript code is executed that triggers this specific code path, the interpreter encounters a scenario where a pointer expected to reference valid function data is instead null, causing an immediate crash. This behavior aligns with CWE-476 which categorizes null pointer dereference as a common weakness in software design. The attack vector requires only the execution of carefully crafted javascript code, making it particularly dangerous in environments where untrusted code execution is possible, such as web applications or embedded systems using Jsish as their javascript engine.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged to create persistent denial of service conditions that may affect system availability and user experience. In embedded systems or applications where Jsish is used for scripting capabilities, this vulnerability could allow attackers to crash the interpreter repeatedly, potentially leading to complete system unavailability. The vulnerability's exploitation does not require elevated privileges or complex attack chains, making it accessible to a broad range of threat actors. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique related to network denial of service, and potentially T1566 for initial compromise through malicious code execution. The fixed version 2.4.84 includes proper null pointer checks and validation mechanisms that prevent the interpreter from attempting to dereference null pointers during function dump operations.
Mitigation strategies for this vulnerability should focus on immediate patch deployment to version 2.4.84 or later, which contains the necessary defensive code modifications. System administrators should also implement input validation measures for javascript code execution environments, particularly in applications where untrusted javascript may be processed. Additional defensive measures include implementing proper error handling and crash recovery mechanisms, as well as monitoring for unusual interpreter termination patterns that may indicate exploitation attempts. Organizations using Jsish in production environments should conduct thorough testing of the patched version to ensure compatibility and stability. The vulnerability serves as a reminder of the importance of proper null pointer validation in interpreter design and highlights the need for comprehensive testing of edge cases in scripting engines. Security teams should also consider implementing runtime protections and sandboxing mechanisms to limit the potential impact of similar vulnerabilities in the future.