CVE-2018-1000668 in Jsish
Summary
by MITRE
jsish version 2.4.70 2.047 contains a CWE-125: Out-of-bounds Read vulnerability in function jsi_ObjArrayLookup (jsiObj.c:274) that can result in Crash due to segmentation fault. This attack appear to be exploitable via The victim must execute crafted javascript code. This vulnerability appears to have been fixed in 2.4.71.
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Analysis
by VulDB Data Team • 03/21/2020
The jsish JavaScript interpreter version 2.4.70 contains a critical out-of-bounds read vulnerability classified as CWE-125 within the jsi_ObjArrayLookup function located in jsiObj.c at line 274. This vulnerability represents a fundamental memory safety issue that occurs when the interpreter processes JavaScript code containing maliciously crafted array operations. The flaw manifests when the interpreter attempts to access memory locations beyond the allocated bounds of an object array structure, leading to unpredictable behavior and system instability. The vulnerability is particularly concerning because it can be triggered through legitimate JavaScript execution paths, making it difficult to detect and prevent through standard input validation measures.
The technical exploitation of this vulnerability requires an attacker to craft specific JavaScript code that will invoke the jsi_ObjArrayLookup function with parameters that cause the out-of-bounds memory access. When the interpreter processes such malicious code, it attempts to read memory locations that are outside the valid range of the object array, resulting in a segmentation fault that causes the application to crash. This crash occurs due to the interpreter's failure to properly validate array indices before accessing array elements, creating a scenario where memory access violations occur in the underlying object management system. The vulnerability's exploitation path demonstrates a classic buffer over-read condition that can be leveraged to cause denial of service or potentially enable more sophisticated attack vectors depending on the execution environment.
The operational impact of this vulnerability extends beyond simple application crashes, as it represents a significant security risk for systems that rely on jsish for JavaScript execution. When exploited successfully, the segmentation fault can lead to complete application termination, potentially disrupting services that depend on the interpreter for dynamic code execution. This vulnerability affects environments where jsish is used as a scripting engine or embedded interpreter, particularly in server-side applications or embedded systems where JavaScript code execution is a core functionality. The vulnerability's presence in version 2.047 and its subsequent fix in 2.4.71 indicates that this was a known issue that required immediate attention to prevent potential exploitation in production environments.
Organizations utilizing jsish should prioritize immediate upgrade to version 2.4.71 or later to mitigate this vulnerability, as the out-of-bounds read condition creates opportunities for attackers to cause system instability and potential service disruption. The fix implemented in version 2.4.71 likely includes proper bounds checking mechanisms within the jsi_ObjArrayLookup function to validate array indices before memory access operations. Security teams should also implement monitoring for unusual application behavior or crash patterns that might indicate exploitation attempts, particularly in environments where JavaScript code execution is permitted. This vulnerability aligns with ATT&CK technique T1059.007 for JavaScript, where adversaries leverage interpreter vulnerabilities to execute malicious code, though the specific exploitation vector requires legitimate JavaScript execution to trigger the memory access violation. The vulnerability demonstrates the importance of proper memory management in interpreted languages and highlights the need for comprehensive input validation and bounds checking in interpreter implementations.