CVE-2011-1997 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 6 does not properly handle objects in memory, which allows remote attackers to execute arbitrary code by accessing a deleted object, aka "OnLoad Event Remote Code Execution Vulnerability."
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 11/23/2021
The vulnerability identified as CVE-2011-1997 represents a critical memory corruption flaw in Microsoft Internet Explorer 6 that stems from improper handling of objects within memory management structures. This vulnerability specifically affects the browser's processing of objects during the OnLoad event, creating a scenario where attackers can manipulate memory references to execute malicious code remotely. The flaw manifests when Internet Explorer attempts to access objects that have already been deleted from memory, leading to unpredictable behavior that adversaries can exploit for code execution. This issue directly relates to CWE-125, which describes out-of-bounds read vulnerabilities, and CWE-787, which covers out-of-bounds write conditions, both of which are fundamental memory safety issues that have plagued software development for decades.
The technical exploitation of this vulnerability occurs through carefully crafted web content that triggers the browser's memory management routines in a way that causes a deleted object reference to be accessed during the OnLoad event processing. When Internet Explorer encounters such malformed content, it fails to properly validate object references, allowing attackers to manipulate memory pointers and execute arbitrary code with the privileges of the user running the browser. The attack vector requires remote code execution through web-based content, making it particularly dangerous as it can be delivered via malicious websites, email attachments, or compromised web applications. This vulnerability aligns with ATT&CK technique T1203, which covers exploitation for execution through memory corruption attacks, and demonstrates how legacy browser vulnerabilities can persist for extended periods due to the slow adoption of security updates in enterprise environments.
The operational impact of CVE-2011-1997 extends beyond simple code execution to encompass complete system compromise, as attackers can leverage this vulnerability to install malware, steal sensitive data, or establish persistent access to affected systems. The vulnerability's exploitation requires no user interaction beyond visiting a malicious webpage, making it particularly dangerous for enterprise environments where users may inadvertently encounter compromised content. Organizations running Internet Explorer 6 are especially vulnerable as this browser version lacks modern security mitigations such as address space layout randomization and data execution prevention that would otherwise make exploitation more difficult. The persistence of this vulnerability across multiple years demonstrates the challenges organizations face when maintaining legacy systems and highlights the importance of proper vulnerability management and patch deployment strategies that align with industry best practices outlined in frameworks such as NIST SP 800-128 for vulnerability management.
Mitigation strategies for CVE-2011-1997 primarily focus on immediate remediation through patch deployment, as Microsoft released security updates specifically addressing this vulnerability. Organizations should implement network-based protections such as web application firewalls and content filtering solutions to block malicious content before it reaches vulnerable systems. Browser isolation techniques and sandboxing can provide additional layers of protection, though these measures are less effective against vulnerabilities that affect core browser functionality. Regular vulnerability assessments and penetration testing should be conducted to identify systems running unsupported browser versions, while security awareness training can help reduce the risk of users encountering malicious content. The vulnerability also underscores the importance of maintaining up-to-date security patches and implementing proper end-of-life management for legacy software components, as outlined in ISO 27001 and other security frameworks that emphasize the need for continuous security monitoring and remediation processes to address known vulnerabilities effectively.