CVE-2018-0991 in Internet Explorer
Summary
by MITRE
A remote code execution vulnerability exists when Internet Explorer improperly accesses objects in memory, aka "Internet Explorer Memory Corruption Vulnerability." This affects Internet Explorer 11, Internet Explorer 10. This CVE ID is unique from CVE-2018-0870, CVE-2018-0997, CVE-2018-1018, CVE-2018-1020.
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Analysis
by VulDB Data Team • 02/09/2021
The vulnerability identified as CVE-2018-0991 represents a critical memory corruption flaw within Microsoft Internet Explorer browsers, specifically affecting versions 11 and 10. This vulnerability falls under the broader category of remote code execution vulnerabilities that exploit improper object handling in memory management systems. The flaw enables attackers to execute arbitrary code on affected systems simply by persuading users to visit malicious websites or open compromised content. The vulnerability is particularly concerning because it leverages the browser's memory management mechanisms in a way that bypasses standard security protections, making it an attractive target for cybercriminals seeking to compromise user systems.
The technical exploitation of CVE-2018-0991 occurs when Internet Explorer encounters specially crafted malicious content that triggers improper memory access patterns during object manipulation. This memory corruption vulnerability typically manifests through heap-based buffer overflows or use-after-free conditions where the browser's JavaScript engine fails to properly validate object references before accessing memory locations. The flaw stems from inadequate bounds checking and memory management procedures within the browser's rendering engine, allowing attackers to manipulate memory contents in ways that can lead to arbitrary code execution. According to CWE classification, this vulnerability maps to CWE-125: Out-of-bounds Read and CWE-787: Out-of-bounds Write, both of which represent common memory safety issues that can lead to privilege escalation and full system compromise.
The operational impact of this vulnerability extends beyond simple browser compromise, as successful exploitation can lead to complete system takeover by adversaries. Attackers can leverage this vulnerability to install malware, steal sensitive data, or establish persistent backdoors within affected environments. The remote nature of the exploit means that users do not need to perform any special actions beyond visiting a malicious website, making it particularly dangerous in targeted attack scenarios. Organizations running affected Internet Explorer versions face significant risk exposure, especially in environments where legacy browser support is maintained for compatibility reasons. The vulnerability's classification under the ATT&CK framework places it within the T1059.001 technique category, which involves command and script interpreter usage, as attackers can execute malicious code directly through the compromised browser environment.
Mitigation strategies for CVE-2018-0991 should prioritize immediate patch deployment through Microsoft's security updates, as this vulnerability was addressed in Microsoft Security Bulletin MS18-034. Organizations should also implement network-based protections such as web application firewalls and content filtering systems to block malicious content before it reaches users. Browser hardening measures including disabling unnecessary features, implementing strict security policies, and using sandboxing techniques can significantly reduce exploitation risk. Additionally, user education regarding suspicious website visits and phishing attempts remains crucial, as social engineering often complements technical exploitation. The vulnerability's age and the availability of comprehensive patches make immediate remediation essential, as the window for exploitation remains open for organizations that have not yet applied the necessary security updates.