CVE-2017-5949 in WebKit
Summary
by MITRE
JavaScriptCore in WebKit, as distributed in Safari Technology Preview Release 22, allows remote attackers to cause a denial of service (heap-based out-of-bounds write and application crash) or possibly have unspecified other impact via crafted JavaScript code that triggers access to red-zone memory locations, related to jit/ThunkGenerators.cpp, llint/LowLevelInterpreter32_64.asm, and llint/LowLevelInterpreter64.asm.
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Analysis
by VulDB Data Team • 11/24/2022
This vulnerability exists within the JavaScriptCore engine component of WebKit, specifically affecting Safari Technology Preview Release 22 and potentially other versions that utilize similar codebases. The flaw manifests as a heap-based out-of-bounds write condition that occurs when processing specially crafted JavaScript code. The vulnerability is particularly concerning because it operates at the Just-In-Time compilation layer of the JavaScript engine, where code is translated into machine instructions for execution. The affected files include jit/ThunkGenerators.cpp which handles the generation of machine code for function calls, along with llint/LowLevelInterpreter32_64.asm and llint/LowLevelInterpreter64.asm which manage the low-level interpretation of JavaScript bytecode. These components work together to optimize JavaScript execution but contain memory access vulnerabilities that can be exploited through malicious script code.
The technical exploitation of this vulnerability involves crafting JavaScript code that triggers memory access patterns leading to out-of-bounds writes in heap memory regions. When the JavaScript engine processes such code, it accesses memory locations in what is known as the red-zone - areas of memory that are typically reserved for specific purposes and should not be accessible through normal program execution paths. This red-zone memory access results in heap corruption that can manifest as application crashes or more severe consequences. The vulnerability's impact extends beyond simple denial of service since the out-of-bounds write could potentially allow attackers to execute arbitrary code or cause other unspecified behaviors. The root cause lies in insufficient bounds checking within the JIT compilation process, where the engine fails to validate memory access patterns before writing to heap locations.
The operational impact of this vulnerability creates significant security risks for users of affected WebKit-based browsers. Remote attackers can leverage this flaw to cause application instability through denial of service attacks, effectively disrupting user sessions and browser functionality. However, the potential for more severe consequences exists, as heap-based out-of-bounds writes can serve as a stepping stone for more sophisticated exploitation techniques. The vulnerability affects not just individual users but represents a potential threat to web application security since it operates within the core JavaScript execution environment that powers modern web applications. Users may be exposed to attacks without their knowledge, as the malicious code could be embedded in web pages or delivered through compromised websites, making this a particularly dangerous flaw in the context of web browser security.
Mitigation strategies for this vulnerability should focus on immediate patching of affected WebKit versions and browser releases. System administrators and users should ensure they are running the latest stable versions of Safari and WebKit-based browsers that contain fixes for this specific issue. The vulnerability's presence in JIT compilation components suggests that updating to versions with improved bounds checking mechanisms is essential. Additionally, organizations should implement browser hardening measures including sandboxing, privilege separation, and content security policies to limit the potential damage from successful exploitation attempts. Security monitoring should include detection of unusual memory access patterns and heap corruption indicators that may signal exploitation attempts. From a compliance perspective, this vulnerability aligns with CWE-121 heap-based buffer overflow weakness and could potentially map to attack patterns in the MITRE ATT&CK framework under the system binary exploitation and privilege escalation categories, particularly when considering the potential for arbitrary code execution through memory corruption.