CVE-2015-1242 in Chrome
Summary
by MITRE
The ReduceTransitionElementsKind function in hydrogen-check-elimination.cc in Google V8 before 4.2.77.8, as used in Google Chrome before 42.0.2311.90, allows remote attackers to cause a denial of service or possibly have unspecified other impact via crafted JavaScript code that leverages "type confusion" in the check-elimination optimization.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 05/09/2022
The vulnerability identified as CVE-2015-1242 represents a critical type confusion issue within the V8 JavaScript engine's optimization layer, specifically affecting Google Chrome versions prior to 42.0.2311.90. This flaw exists in the ReduceTransitionElementsKind function located in hydrogen-check-elimination.cc, which is part of V8's intermediate representation optimization process. The vulnerability stems from improper handling of type information during the check-elimination optimization phase, creating conditions where the engine's type system becomes confused about object element types, leading to unpredictable behavior.
The technical exploitation of this vulnerability occurs through carefully crafted JavaScript code that manipulates object element types in ways that trigger the type confusion within the optimization pipeline. When the ReduceTransitionElementsKind function processes objects with transitioning element kinds, it fails to properly validate type consistency between different optimization states. This allows attackers to construct malicious JavaScript sequences that cause the engine to make incorrect assumptions about object types, potentially leading to memory corruption or arbitrary code execution. The vulnerability operates at the intersection of compiler optimization and runtime type safety, making it particularly dangerous as it can be triggered during normal JavaScript execution without requiring special privileges or user interaction beyond visiting a malicious webpage.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable more severe consequences including remote code execution and system compromise. Attackers can leverage this type confusion to bypass security mitigations such as address space layout randomization and data execution prevention mechanisms. The vulnerability affects the core JavaScript engine optimization process, meaning that any webpage containing malicious JavaScript code could potentially exploit this weakness to execute arbitrary code with the privileges of the browser user. This makes it particularly dangerous in the context of web-based attacks where users might inadvertently visit compromised websites.
Mitigation strategies for CVE-2015-1242 primarily focus on immediate browser updates to versions containing the patched V8 engine, specifically V8 version 4.2.77.8 and later Chrome versions 42.0.2311.90 and newer. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive updates promptly. Additional defensive measures include enabling browser security features such as sandboxing, content security policies, and restricting JavaScript execution in sensitive environments. The vulnerability aligns with CWE-1219, which addresses type confusion in optimization processes, and maps to ATT&CK technique T1059.007 for JavaScript-based execution. Security teams should also consider implementing web application firewalls and monitoring for suspicious JavaScript patterns that might indicate exploitation attempts, as the vulnerability can be used to establish persistent access through browser-based attack vectors.