CVE-2018-0818 in ChakraCore
Summary
by MITRE
Microsoft ChakraCore allows an attacker to bypass Control Flow Guard (CFG) in conjunction with another vulnerability to run arbitrary code on a target system, due to how the Chakra scripting engine handles accessing memory, aka "Scripting Engine Security Feature Bypass".
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Analysis
by VulDB Data Team • 12/29/2019
Microsoft ChakraCore represents a critical vulnerability in the Windows operating system's scripting engine that enables attackers to circumvent essential security protections through a sophisticated exploitation technique. This vulnerability specifically targets the Control Flow Guard mechanism, a security feature designed to prevent attackers from executing arbitrary code by ensuring that program execution follows legitimate control flow paths. The flaw exists within how Chakra processes memory access operations, creating a pathway for malicious actors to bypass these protective measures and gain unauthorized system access. The vulnerability operates as a secondary exploit that relies on the combination of Control Flow Guard bypass and another underlying vulnerability to achieve successful code execution, making it particularly dangerous in targeted attack scenarios where attackers can chain multiple exploits together for maximum impact. Security researchers have classified this issue under the broader category of scripting engine security feature bypass vulnerabilities, which fall under the CWE-119 weakness category related to memory safety issues and improper access to memory locations.
The technical implementation of this vulnerability stems from how ChakraCore handles memory access patterns during script execution, particularly when dealing with dynamic code generation and memory management operations. Attackers can leverage this flaw to manipulate the control flow of legitimate programs, redirecting execution to malicious payloads that would normally be blocked by Control Flow Guard protections. The exploit requires a sophisticated understanding of both the ChakraCore engine internals and the operating system's security mechanisms, as it exploits the interaction between multiple security layers rather than targeting a single point of failure. This characteristic places the vulnerability in the ATT&CK framework under the T1059 technique category for command and scripting interpreter, specifically targeting the scripting engine as a vector for privilege escalation. The exploitation process typically involves crafting malicious JavaScript code that can manipulate memory pointers and function addresses in a way that bypasses the normal execution flow checks implemented by CFG.
The operational impact of CVE-2018-0818 extends beyond simple code execution capabilities, as it provides attackers with a powerful tool for establishing persistent access to compromised systems. When successfully exploited, this vulnerability enables attackers to execute arbitrary code with the privileges of the targeted application, potentially leading to full system compromise. The vulnerability's effectiveness is heightened when combined with other exploitation techniques, as it allows attackers to build more sophisticated attack chains that can evade detection mechanisms and maintain long-term access to target systems. Organizations running systems with ChakraCore-enabled applications face significant risk, particularly those that execute untrusted script content or have web applications that utilize JavaScript engines. The vulnerability affects various Microsoft products including Internet Explorer, Edge browser, and other applications that rely on ChakraCore for JavaScript execution, making it a widespread concern across enterprise environments and consumer systems. Security professionals must understand that this vulnerability represents a critical weakness in the security architecture of Windows-based systems, as it demonstrates how seemingly isolated security features can be bypassed through careful exploitation of underlying implementation flaws.
Mitigation strategies for this vulnerability require immediate patch deployment from Microsoft, as the primary fix involves updating the ChakraCore engine to properly handle memory access operations and maintain proper control flow protections. Organizations should implement network segmentation and application whitelisting to limit the potential impact of successful exploitation attempts, while also monitoring for unusual script execution patterns that might indicate attempted exploitation. System administrators should prioritize updating all affected Microsoft products and ensure that automatic update mechanisms are enabled to prevent exploitation through delayed patch management. The vulnerability also highlights the importance of maintaining up-to-date security monitoring tools that can detect anomalous behavior patterns associated with control flow manipulation and memory access violations. Additional protective measures include implementing strict browser security policies, disabling unnecessary scripting capabilities in web applications, and conducting regular security assessments to identify potential attack vectors that could leverage similar weaknesses in other components of the system architecture. Organizations should also consider implementing advanced threat detection mechanisms that can identify and block exploitation attempts targeting scripting engine vulnerabilities, as these types of attacks often follow predictable patterns that can be detected through behavioral analysis and anomaly detection systems.