CVE-2015-6056 in Internet Explorer
Summary
by MITRE
The (1) JScript and (2) VBScript engines in Microsoft Internet Explorer 9 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."
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Analysis
by VulDB Data Team • 06/21/2022
The vulnerability identified as CVE-2015-6056 represents a critical memory corruption flaw affecting the scripting engines within Microsoft Internet Explorer versions 9 through 11. This vulnerability specifically impacts both JScript and VBScript engines, which are integral components responsible for executing client-side scripts on web pages. The flaw enables remote attackers to exploit the memory management mechanisms within these engines, creating opportunities for arbitrary code execution or deliberate denial of service conditions. The vulnerability stems from improper handling of memory allocation and deallocation processes within the scripting engine's runtime environment, particularly when processing malformed or crafted script content that triggers buffer overflows or use-after-free conditions. The attack vector involves visiting a malicious website that contains specially crafted script code designed to exploit these memory handling weaknesses.
The technical implementation of this vulnerability involves memory corruption within the JavaScript and VBScript engines that process web content in Internet Explorer. When the affected browsers encounter malicious script code, the scripting engine's memory management routines fail to properly validate input parameters or handle memory operations, leading to memory corruption states that can be leveraged by attackers. The vulnerability manifests through improper bounds checking during script execution, particularly when dealing with dynamic memory allocation for script objects and variables. Attackers can craft specific web pages containing malicious scripts that trigger heap corruption or stack overflow conditions, allowing them to overwrite critical memory locations or inject malicious code into the browser process memory space. This type of vulnerability is classified as a memory corruption vulnerability and maps to CWE-121, which describes heap-based buffer overflow conditions.
The operational impact of CVE-2015-6056 extends beyond simple exploitation capabilities to encompass significant security risks for enterprise and individual users. Successful exploitation can result in complete system compromise, as attackers can execute arbitrary code with the privileges of the logged-in user, potentially leading to full system control. The vulnerability affects a broad range of Internet Explorer versions, making it particularly dangerous as it targets widely deployed browser software across both enterprise and consumer environments. Organizations running older versions of Internet Explorer face substantial risk exposure, as the vulnerability can be exploited through simple web browsing activities without requiring any user interaction beyond visiting a malicious site. The denial of service aspect of this vulnerability can also be weaponized to create persistent availability issues for affected systems, particularly in enterprise environments where browser stability is critical for business operations.
Mitigation strategies for CVE-2015-6056 should prioritize immediate patch deployment through Microsoft's security updates, as the vulnerability requires specific fixes to address the underlying memory management flaws in the scripting engines. Organizations should implement browser hardening measures including disabling scripting engines for untrusted sites, implementing content security policies, and using browser sandboxing technologies to limit the impact of successful exploitation attempts. Network-level defenses such as web application firewalls and intrusion prevention systems can help detect and block known malicious script patterns associated with this vulnerability. The ATT&CK framework categorizes this vulnerability under technique T1059.007 for Windows Scripting and T1203 for Exploitation for Client Execution, highlighting the need for layered defensive approaches including endpoint detection and response capabilities. Additionally, organizations should consider implementing browser isolation technologies and maintaining up-to-date threat intelligence feeds to identify and block exploit attempts targeting this specific vulnerability. Regular security assessments and vulnerability scanning should be conducted to ensure all affected systems have received appropriate patches and that no legacy browser installations remain exposed to this risk.