CVE-2016-0191 in Edge
Summary
by MITRE
The Chakra JavaScript engine in Microsoft Edge allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted web site, aka "Scripting Engine Memory Corruption Vulnerability," a different vulnerability than CVE-2016-0186 and CVE-2016-0193.
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Analysis
by VulDB Data Team • 08/18/2022
The vulnerability identified as CVE-2016-0191 represents a critical memory corruption flaw within Microsoft Edge's Chakra JavaScript engine, which serves as the core execution environment for JavaScript code in the browser. This vulnerability specifically affects the scripting engine's handling of memory management during JavaScript execution, creating a pathway for remote code execution attacks. The flaw manifests when malicious web content triggers improper memory operations that can lead to arbitrary code execution or system crashes. Security researchers have classified this issue as a remote code execution vulnerability that can be exploited through web-based attacks without requiring user interaction beyond visiting a malicious website.
The technical nature of this vulnerability stems from improper memory management within the Chakra engine's JavaScript compilation and execution processes. When processing certain JavaScript constructs, the engine fails to properly validate memory boundaries, leading to buffer overflows or use-after-free conditions that can be manipulated by attackers to overwrite critical memory locations. This memory corruption occurs during the dynamic compilation and execution of JavaScript code, particularly when handling complex object manipulations or array operations. The vulnerability's classification as a memory corruption issue places it within the common weakness enumeration CWE-125, which deals with out-of-bounds reads, and CWE-787, which addresses out-of-bounds writes. The attack vector requires no local privileges and can be executed entirely through web-based delivery mechanisms, making it particularly dangerous for widespread exploitation.
The operational impact of CVE-2016-0191 extends beyond simple denial of service scenarios to encompass full system compromise capabilities for attackers. When successfully exploited, this vulnerability allows adversaries to execute arbitrary code with the privileges of the Edge browser process, potentially leading to complete system compromise. The memory corruption can be leveraged to bypass modern security mitigations such as address space layout randomization and data execution prevention, particularly when combined with other exploitation techniques. The vulnerability affects Microsoft Edge versions prior to the security updates released in February 2016, making it a significant concern for organizations running outdated browser versions. The attack surface is broad as it can be triggered through any web content that utilizes JavaScript, including legitimate websites that have been compromised or malicious sites designed specifically for exploitation.
Mitigation strategies for CVE-2016-0191 primarily focus on immediate patch deployment and browser security hardening measures. Microsoft released security updates in February 2016 that addressed the memory corruption issues within the Chakra engine, and organizations should prioritize applying these patches to all affected systems. Additionally, implementing browser security controls such as enabling enhanced protection modes, restricting JavaScript execution in sensitive contexts, and deploying web application firewalls can help reduce the attack surface. Network-level defenses including content filtering and sandboxing mechanisms can provide additional protection layers. Security teams should also consider implementing monitoring for unusual JavaScript behavior patterns and memory access anomalies that may indicate exploitation attempts. The vulnerability's characteristics align with tactics described in the attack framework, particularly those involving initial access through web-based phishing campaigns and privilege escalation through browser exploitation techniques. Organizations should also conduct regular security assessments to identify and remediate similar vulnerabilities in other browser components and web technologies.