CVE-2017-9250 in JerryScript
Summary
by MITRE
The lexer_process_char_literal function in jerry-core/parser/js/js-lexer.c in JerryScript 1.0 does not skip memory allocation for empty strings, which allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via malformed JavaScript source code, related to the jmem_heap_free_block function.
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Analysis
by VulDB Data Team • 12/07/2022
The vulnerability identified as CVE-2017-9250 resides within the JerryScript JavaScript engine version 1.0, specifically within the js-lexer.c file where the lexer_process_char_literal function fails to properly handle memory allocation for empty string scenarios. This flaw represents a classic memory management issue that can be exploited to disrupt application functionality through carefully crafted malicious input. The vulnerability manifests when the parser encounters malformed JavaScript source code containing empty character literals, causing the memory allocator to attempt operations on uninitialized or improperly managed memory regions.
The technical execution of this vulnerability occurs through the jmem_heap_free_block function which is responsible for memory deallocation within the JerryScript memory management system. When the lexer_process_char_literal function processes empty string literals, it fails to properly allocate memory for these constructs, leading to a NULL pointer dereference condition. This memory allocation failure creates a cascade of errors that ultimately results in application crash, effectively enabling a denial of service attack against systems running vulnerable JerryScript implementations. The flaw demonstrates poor input validation and memory handling practices that are commonly associated with buffer overflow and memory corruption vulnerabilities.
From an operational perspective, this vulnerability presents significant risk to web applications and embedded systems that utilize JerryScript for JavaScript execution. Attackers can exploit this weakness by submitting malformed JavaScript code containing empty character literals, which will trigger the memory allocation failure and subsequent application crash. The impact extends beyond simple service disruption as this vulnerability can be leveraged in automated attack scenarios to repeatedly crash services, potentially leading to system instability or complete application unavailability. Organizations relying on JerryScript for server-side JavaScript processing or embedded device applications are particularly vulnerable to this type of attack.
The vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions, and represents a specific instance of improper memory management within JavaScript engine implementations. From an attack framework perspective, this vulnerability would fall under the denial of service category within the MITRE ATT&CK framework, potentially enabling broader attack chains if combined with other vulnerabilities. The flaw's exploitation requires minimal complexity and can be automated, making it attractive to threat actors seeking to disrupt services. Organizations should prioritize patching this vulnerability through updated JerryScript versions, implementing input validation measures, and monitoring for exploitation attempts. Additional mitigations include restricting JavaScript execution in sensitive environments, employing sandboxing techniques, and deploying intrusion detection systems to identify potential exploitation attempts targeting this specific memory management flaw.