CVE-2015-6136 in Internet Explorer
Summary
by MITRE
The Microsoft (1) VBScript 5.7 and 5.8 and (2) JScript 5.7 and 5.8 engines, as used in Internet Explorer 8 through 11 and other products, allow remote attackers to execute arbitrary code via a crafted web site, aka "Scripting Engine Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 06/29/2022
The vulnerability identified as CVE-2015-6136 represents a critical memory corruption flaw affecting Microsoft's scripting engines within Internet Explorer and related software components. This vulnerability specifically impacts VBScript versions 5.7 and 5.8, as well as JScript versions 5.7 and 5.8, creating a significant attack surface that has been exploited by threat actors targeting web browsers and enterprise environments. The flaw resides in how these scripting engines handle memory operations during script execution, creating opportunities for attackers to manipulate memory layout and execute malicious code remotely. The vulnerability affects Internet Explorer versions 8 through 11, making it particularly dangerous given the widespread deployment of these browser versions across enterprise networks and user environments. This issue falls under the CWE-125 weakness category, which describes out-of-bounds read vulnerabilities, and aligns with ATT&CK technique T1059.007 for script-based execution in Windows environments.
The technical implementation of this vulnerability stems from improper memory management within the scripting engine's memory allocation and deallocation processes. When processing crafted web content, the VBScript and JScript engines fail to properly validate memory boundaries during script execution, allowing attackers to manipulate memory pointers and overwrite critical memory regions. This memory corruption can be leveraged to execute arbitrary code with the privileges of the victim user, potentially leading to full system compromise. The vulnerability is particularly concerning because it can be triggered through standard web browsing activities without requiring any special user interaction beyond visiting a malicious website. Attackers can craft specially designed web pages that exploit the memory corruption to inject and execute malicious payloads, often leveraging the browser's scripting capabilities to bypass traditional security controls.
The operational impact of CVE-2015-6136 extends far beyond individual user compromise, affecting enterprise security postures and requiring immediate remediation across affected systems. Organizations running Internet Explorer 8 through 11 are particularly vulnerable, as these browsers continue to be deployed in legacy environments where patching may be delayed or restricted. The vulnerability enables attackers to establish persistent access, escalate privileges, and potentially move laterally within networks, making it a prime target for advanced persistent threat campaigns. Security teams must consider this vulnerability as part of broader threat hunting activities, particularly when analyzing browser-based attack vectors and memory corruption exploits. The remote execution capability means that successful exploitation can occur without any local access to the target system, making it especially dangerous for organizations with limited network segmentation or robust endpoint protection controls.
Mitigation strategies for CVE-2015-6136 should prioritize immediate patch deployment from Microsoft, as the vendor released security updates specifically addressing this vulnerability through the Microsoft Security Response Center. Organizations should implement browser hardening measures including disabling scripting engines in non-essential contexts, implementing strict content security policies, and utilizing sandboxing technologies to limit potential damage from successful exploitation attempts. Network-based protections should include web application firewalls and intrusion detection systems configured to detect and block malicious script execution patterns. Additionally, security teams should conduct comprehensive vulnerability assessments to identify systems running affected browser versions and implement layered defensive controls including email filtering, web proxy configurations, and user education about safe browsing practices. The vulnerability demonstrates the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies to protect against memory corruption exploits that leverage scripting engine vulnerabilities.