CVE-2018-20201 in Espruino
Summary
by MITRE
There is a stack-based buffer over-read in the jsfNameFromString function of jsflash.c in Espruino 2V00, leading to a denial of service or possibly unspecified other impact via a crafted js file.
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Analysis
by VulDB Data Team • 06/19/2023
The vulnerability identified as CVE-2018-20201 represents a critical stack-based buffer over-read flaw within the Espruino JavaScript interpreter version 2V00. This issue specifically affects the jsfNameFromString function located in the jsflash.c source file, which serves as a crucial component in the JavaScript compilation and execution process for embedded systems. The Espruino platform is widely utilized for microcontroller-based JavaScript environments, making this vulnerability particularly concerning for IoT devices and embedded applications that rely on this interpreter for runtime execution of JavaScript code.
The technical flaw manifests when the jsfNameFromString function processes input strings without proper bounds checking, allowing an attacker to craft malicious JavaScript files that trigger a buffer over-read condition. This occurs because the function attempts to read memory locations beyond the allocated buffer boundaries when parsing certain string inputs. The vulnerability stems from inadequate input validation and memory management practices within the JavaScript parsing subsystem, creating a scenario where crafted input can cause the interpreter to access invalid memory regions. This type of flaw falls under CWE-121 Stack-based Buffer Overflow, which is classified as a fundamental memory safety issue that can lead to unpredictable behavior and system instability.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially encompass more severe consequences including system crashes, arbitrary code execution, or data corruption within affected embedded systems. When exploited, the buffer over-read can cause the Espruino interpreter to crash or behave unpredictably, rendering the embedded device inoperable until manual intervention or system reboot occurs. The vulnerability's potential for unspecified other impacts suggests that under certain conditions, attackers might be able to leverage this flaw for more sophisticated attacks, particularly in environments where the interpreter has access to sensitive system resources or where multiple vulnerabilities exist within the same codebase. This makes the vulnerability particularly dangerous in IoT deployments where devices may not have easy access for manual recovery or updates.
Mitigation strategies for CVE-2018-20201 should prioritize immediate firmware updates from Espruino developers, as the most effective solution involves patching the underlying source code to implement proper bounds checking within the jsfNameFromString function. Organizations should also implement input validation measures at the application level, ensuring that all JavaScript files processed by the interpreter are sanitized and validated before execution. Network segmentation and access controls should be enforced to limit exposure of vulnerable devices to untrusted JavaScript content, while monitoring systems should be deployed to detect potential exploitation attempts through anomalous behavior patterns. Additionally, security researchers and developers should consider implementing runtime protections such as stack canaries or address space layout randomization to reduce the exploitability of similar buffer over-read vulnerabilities. The ATT&CK framework categorizes this type of vulnerability under T1059.007 Command and Scripting Interpreter JavaScript, highlighting the importance of securing interpreted environments and the potential for privilege escalation through such memory corruption flaws.