CVE-2011-1998 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 9 does not properly handle objects in memory, which allows remote attackers to execute arbitrary code by accessing an object that was not properly initialized, aka "Jscript9.dll Remote Code Execution Vulnerability."
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Analysis
by VulDB Data Team • 11/23/2021
The vulnerability identified as CVE-2011-1998 represents a critical memory corruption flaw in Microsoft Internet Explorer 9 that resides within the jscript9.dll component responsible for JavaScript execution. This issue stems from improper handling of memory objects during the JavaScript parsing and execution process, creating a condition where uninitialized memory structures can be accessed by malicious code. The vulnerability specifically affects the scripting engine's ability to manage object lifecycles and memory allocation, particularly when processing certain JavaScript constructs that result in objects being accessed before their proper initialization sequence has completed. Attackers can exploit this weakness by crafting malicious web pages that trigger the execution of JavaScript code designed to manipulate these improperly initialized objects, ultimately leading to arbitrary code execution on the victim's system. The flaw demonstrates a classic memory safety issue that aligns with CWE-476, which describes NULL pointer dereference vulnerabilities, though in this case the issue manifests as improper object initialization rather than simple pointer dereference.
The operational impact of this vulnerability extends far beyond simple code execution, as it provides attackers with a powerful foothold for more sophisticated attacks within the target environment. When successfully exploited, the vulnerability allows remote attackers to execute malicious code with the privileges of the logged-in user, potentially leading to complete system compromise. The attack vector requires the victim to visit a malicious website or open a specially crafted email attachment containing web-based content, making it particularly dangerous in social engineering campaigns. The vulnerability's exploitation can lead to various malicious outcomes including credential theft, data exfiltration, installation of additional malware, or establishment of persistent backdoors. According to ATT&CK framework, this vulnerability maps to T1059.007 for JavaScript execution and T1068 for exploit development, representing how adversaries can leverage such flaws to establish initial access and maintain persistence within compromised systems.
Mitigation strategies for CVE-2011-1998 require immediate action through Microsoft's security patches and updates, as the vulnerability was addressed through the Microsoft Security Bulletin MS11-045 released in July 2011. Organizations should prioritize deployment of the relevant security update across all affected systems running Internet Explorer 9, as the vulnerability remains exploitable until patched. Additional protective measures include implementing browser hardening techniques such as disabling JavaScript in trusted environments, deploying enhanced security configurations through group policies, and utilizing sandboxing technologies to limit the potential damage from successful exploitation attempts. Network-based mitigations can involve implementing web application firewalls and content filtering solutions that can detect and block known malicious patterns associated with this vulnerability. Security monitoring should focus on detecting anomalous JavaScript execution patterns and unusual network connections that might indicate exploitation attempts, while user education remains crucial to prevent social engineering attacks that leverage this vulnerability. The vulnerability's classification as a remote code execution flaw underscores the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies to protect against such critical threats.