CVE-2003-0233 in Internet Explorer
Summary
by MITRE
Heap-based buffer overflow in plugin.ocx for Internet Explorer 5.01, 5.5 and 6.0 allows remote attackers to execute arbitrary code via the Load() method, a different vulnerability than CVE-2003-0115.
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Analysis
by VulDB Data Team • 03/08/2021
The vulnerability described in CVE-2003-0233 represents a critical heap-based buffer overflow affecting Internet Explorer versions 5.01, 5.5, and 6.0 through the plugin.ocx component. This flaw specifically manifests when the Load() method is invoked, creating a dangerous condition that enables remote code execution attacks. The vulnerability operates at the heap memory level, where insufficient bounds checking allows attackers to overwrite adjacent memory locations with malicious data, potentially leading to complete system compromise.
The technical nature of this vulnerability aligns with CWE-121, which categorizes heap-based buffer overflows as a fundamental memory safety issue. The flaw exploits the improper handling of input data within the plugin.ocx ActiveX control, where the Load() method fails to validate the size of incoming data before copying it into fixed-length heap buffers. This allows attackers to craft specially formatted input that exceeds the allocated buffer space, causing memory corruption that can be leveraged for arbitrary code execution.
From an operational perspective, this vulnerability presents a severe risk to organizations relying on older Internet Explorer versions, as it enables remote attackers to execute malicious code without requiring any user interaction beyond visiting a compromised website. The attack vector operates entirely through web-based delivery, making it particularly dangerous for enterprise environments where users may inadvertently access malicious content. The vulnerability's impact extends beyond individual system compromise to potentially enable lateral movement within networks, as compromised systems can serve as launching points for further attacks.
The attack surface for CVE-2003-0233 aligns with several ATT&CK techniques including T1190 for Exploit Public-Facing Application and T1059 for Command and Scripting Interpreter. The vulnerability's exploitation typically involves crafting malicious web content that triggers the vulnerable Load() method through ActiveX controls, bypassing many traditional security measures that focus on network-level threats. Organizations should consider implementing browser isolation techniques and maintaining strict patch management policies to prevent exploitation of this and similar legacy vulnerabilities.
Mitigation strategies for this vulnerability primarily involve immediate patching of affected Internet Explorer versions, as Microsoft released security updates addressing the heap overflow conditions. Network-based protections such as web application firewalls and content filtering systems can provide additional defense layers, though they may not prevent exploitation of this specific vulnerability. Security teams should also conduct comprehensive inventory assessments to identify all systems running vulnerable versions of Internet Explorer and prioritize their remediation. The vulnerability serves as a prime example of why organizations must maintain current security postures and why legacy software systems pose ongoing risks that require careful management and eventual retirement.