CVE-2015-6089 in Internet Explorer
Summary
by MITRE
The Microsoft (1) VBScript and (2) JScript engines, as used in Internet Explorer 8 through 11, allow 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."
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 11/28/2024
The CVE-2015-6089 vulnerability represents a critical memory corruption flaw affecting the scripting engines within Microsoft Internet Explorer versions 8 through 11. This vulnerability impacts both VBScript and JScript engines, which are integral components of the browser's client-side scripting capabilities. The vulnerability arises from improper handling of memory allocation and deallocation during script execution, creating opportunities for attackers to exploit memory corruption patterns that can lead to arbitrary code execution or denial of service conditions.
The technical flaw stems from insufficient bounds checking and memory management within the scripting engine's interpreter. When processing malformed or crafted web content, the vulnerable engines fail to properly validate memory operations, leading to buffer overflows, use-after-free conditions, or other memory corruption scenarios. These conditions occur during the parsing and execution of JavaScript or VBScript code, particularly when handling complex objects or arrays with improper memory references. The vulnerability is classified under CWE-125 as an out-of-bounds read condition and CWE-787 as an out-of-bounds write, both of which are common vectors for remote code execution in scripting engines.
The operational impact of this vulnerability is severe, as it enables remote code execution without requiring user interaction beyond visiting a malicious website. Attackers can craft web pages that trigger the memory corruption conditions when Internet Explorer processes the embedded scripts, potentially allowing them to execute arbitrary code with the privileges of the logged-in user. This makes the vulnerability particularly dangerous in enterprise environments where users may browse untrusted websites or encounter phishing attacks. The vulnerability affects all supported versions of Internet Explorer from version 8 through 11, representing a significant attack surface for threat actors targeting Windows environments.
This vulnerability aligns with several ATT&CK techniques including T1059.007 for scripting with JavaScript and T1059.005 for scripting with VBScript, as well as T1203 for exploitation for privilege escalation. The attack typically follows the pattern of delivering malicious web content through spearphishing emails, compromised websites, or drive-by download scenarios. Organizations should implement multiple layers of defense including browser hardening, network-based protections, and regular patch management. Microsoft released security updates through Windows Update and the Microsoft Security Response Center, emphasizing the importance of timely patch deployment. The vulnerability also highlights the need for sandboxing mechanisms and application whitelisting to limit the impact of such exploits in enterprise environments.
The exploitation of this vulnerability demonstrates the ongoing challenges in securing complex scripting engines within web browsers, where the balance between functionality and security remains delicate. The memory corruption patterns exploited in CVE-2015-6089 are characteristic of the types of vulnerabilities found in legacy browser components that have accumulated over years of feature additions and compatibility requirements. Security professionals should consider implementing web application firewalls and content security policies as additional protective measures. The vulnerability underscores the critical importance of maintaining up-to-date browser versions and the risks associated with continued use of unsupported software versions, as the affected Internet Explorer versions are no longer receiving security updates from Microsoft.