CVE-2015-2391 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 9 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."
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Analysis
by VulDB Data Team • 05/31/2022
Microsoft Internet Explorer 9 contains a critical memory corruption vulnerability that enables remote attackers to execute arbitrary code or induce denial of service conditions through maliciously crafted web content. This vulnerability represents a classic heap-based buffer overflow scenario where improper input validation allows attackers to manipulate memory structures during web page rendering. The flaw specifically manifests when IE processes certain HTML elements or JavaScript code that triggers memory allocation errors, leading to potential code execution in the context of the current user. The vulnerability is particularly dangerous because it can be exploited through standard web browsing activities without requiring any special privileges or user interaction beyond visiting a compromised website.
The technical root cause of CVE-2015-2391 lies in the improper handling of memory operations within IE9's rendering engine, specifically in how the browser manages dynamic memory allocation for web content. When processing malformed or specially crafted HTML elements, the browser fails to properly validate memory boundaries, allowing attackers to overwrite adjacent memory locations with malicious code. This type of vulnerability is classified as a memory corruption flaw under CWE-125, which encompasses out-of-bounds read and write conditions that can lead to arbitrary code execution. The vulnerability affects the browser's JavaScript engine and HTML parser, making it particularly insidious as it can be triggered through various web page elements including embedded scripts, images, or even CSS styling directives.
The operational impact of this vulnerability extends beyond simple code execution to encompass potential system compromise and data theft. Attackers can leverage this flaw to install malware, steal user credentials, or establish persistent backdoors on affected systems. The vulnerability's remote exploitability means that attackers need only convince victims to visit malicious websites, making it particularly dangerous in phishing campaigns or drive-by download scenarios. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1203, which describes exploitation of software vulnerabilities for privilege escalation and persistence. The memory corruption aspect also maps to ATT&CK technique T1059, where adversaries use command and control channels to execute malicious code through compromised browsers.
Organizations should implement immediate mitigations including applying Microsoft's security patches and updates as soon as they become available. Browser isolation techniques and network-based protections such as web application firewalls can provide additional defense layers. Security teams should monitor for exploitation attempts through network traffic analysis and endpoint detection systems. User education regarding safe browsing practices and avoiding suspicious websites remains crucial. The vulnerability highlights the importance of keeping browser software updated and implementing layered security approaches. Organizations should also consider implementing browser hardening measures such as disabling unnecessary plugins and restricting JavaScript execution in sensitive environments. Regular security assessments and vulnerability scanning should include checks for outdated browser versions that may be susceptible to similar memory corruption flaws.