CVE-2015-6156 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 9 through 11 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted web site, aka "Internet Explorer Memory Corruption Vulnerability," a different vulnerability than CVE-2015-6148.
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Analysis
by VulDB Data Team • 11/18/2024
Microsoft Internet Explorer versions 9 through 11 contained a critical memory corruption vulnerability that enabled remote code execution through crafted web content. This vulnerability specifically affected the browser's handling of memory management during web page rendering processes, creating a condition where malicious actors could manipulate memory structures to execute arbitrary code on vulnerable systems. The flaw manifested when Internet Explorer processed specially crafted HTML elements or JavaScript code that triggered improper memory deallocation or buffer overflow conditions. This vulnerability represented a distinct issue from CVE-2015-6148, indicating separate memory management flaws within the browser's architecture. The technical implementation involved memory corruption patterns that could be exploited through web-based attacks without requiring user interaction beyond visiting a malicious website, making it particularly dangerous for enterprise environments where users frequently access untrusted web content. The vulnerability's impact extended beyond simple code execution to include potential denial of service scenarios where system stability could be compromised through memory corruption attacks. According to CWE classification, this vulnerability aligns with CWE-119 Improper Access to Memory and CWE-787 Out-of-bounds Write, both of which describe memory safety issues in software applications. The ATT&CK framework categorizes this vulnerability under T1203 Exploitation for Client Execution, highlighting how attackers could leverage browser vulnerabilities to gain unauthorized code execution on target systems. The exploitation typically required crafting malicious web pages that would trigger the memory corruption when rendered by the vulnerable browser versions, often involving complex JavaScript or HTML manipulation techniques. Organizations using these older Internet Explorer versions faced significant risk due to the widespread adoption of these browsers in enterprise environments, where the vulnerability could be leveraged for privilege escalation attacks or as a foothold for broader network infiltration. The vulnerability's persistence across multiple versions of Internet Explorer indicated a fundamental flaw in the browser's memory management subsystem that required comprehensive patching or browser replacement strategies. Security researchers noted that the vulnerability's exploitation was relatively straightforward for skilled attackers, making it a popular target for cybercriminals seeking to compromise systems through web-based attack vectors.
The memory corruption vulnerability in Internet Explorer 9 through 11 stemmed from improper handling of memory allocation and deallocation during web page rendering processes. When the browser encountered crafted HTML elements or JavaScript code, it would execute memory operations that led to buffer overflows or use-after-free conditions, allowing attackers to manipulate memory contents and redirect execution flow. This type of vulnerability is particularly dangerous because it can be triggered automatically when visiting a malicious website, requiring no user interaction beyond navigating to the compromised page. The flaw existed in the browser's scripting engine and rendering pipeline, where memory management functions failed to properly validate input data or maintain proper memory boundaries during object creation and destruction. Attackers could leverage this vulnerability by constructing web pages that would cause the browser to allocate memory in specific patterns that would later be corrupted through malicious code execution. The vulnerability's classification under CWE-119 and CWE-787 indicates that it involved improper memory access patterns that allowed attackers to write data beyond allocated memory boundaries. This memory corruption could be exploited to overwrite critical memory locations, including function pointers or return addresses, enabling attackers to execute arbitrary code with the privileges of the running browser process. The attack surface was extensive given that Internet Explorer was widely used across corporate environments, making the vulnerability particularly attractive to threat actors seeking to compromise large numbers of systems simultaneously. Organizations that had not updated their browsers to supported versions remained vulnerable to this exploitation vector, which could be combined with other attack techniques to create more sophisticated compromise scenarios. The vulnerability's impact was amplified by the fact that it could be triggered through various attack vectors including email attachments, web downloads, or drive-by downloads from compromised websites. Security professionals recommended immediate patching of affected systems and implementation of browser isolation techniques to mitigate the risk of exploitation. The vulnerability also highlighted the importance of maintaining up-to-date browser software and implementing security controls such as content filtering and web application firewalls to prevent access to malicious websites. Microsoft's security response included releasing patches that addressed the memory corruption issues in the affected browser versions, but organizations needed to ensure comprehensive deployment across all affected systems to achieve full protection.
Mitigation strategies for CVE-2015-6156 required immediate action from organizations to protect their systems from exploitation. The most effective approach involved applying Microsoft's security patches that addressed the specific memory corruption vulnerabilities in Internet Explorer 9 through 11 versions. Organizations should have implemented comprehensive patch management processes to ensure all affected systems received updates promptly. Browser isolation techniques such as using sandboxing mechanisms or running Internet Explorer in restricted environments could provide additional protection against exploitation attempts. Network security controls including web proxies, content filtering systems, and intrusion prevention systems helped detect and block access to malicious websites that might exploit this vulnerability. Security teams needed to implement monitoring solutions that could detect unusual memory access patterns or browser behavior that might indicate exploitation attempts. The vulnerability's classification under ATT&CK framework's T1203 category emphasized the need for endpoint security solutions that could prevent client-side exploitation attempts. Organizations should have considered migrating away from Internet Explorer to more modern browsers with better security track records and more frequent security updates. User education programs about the risks of visiting untrusted websites and the importance of keeping software updated helped reduce the likelihood of successful exploitation. Security assessments should have focused on identifying all systems running vulnerable Internet Explorer versions and prioritizing patch deployment based on risk exposure. The vulnerability also highlighted the importance of maintaining comprehensive backup and recovery procedures in case of successful exploitation attempts. Regular security audits and vulnerability scanning helped organizations identify systems that remained vulnerable despite patching efforts. Incident response procedures needed to be updated to include specific guidance for handling potential exploitation attempts related to this vulnerability, ensuring rapid response to any detected compromise attempts. The broader security community recognized that this vulnerability demonstrated the critical importance of maintaining current browser security and the potential consequences of running outdated software in enterprise environments.