CVE-2000-0156 in Internet Explorer
Summary
by MITRE
Internet Explorer 4.x and 5.x allows remote web servers to access files on the client that are outside of its security domain, aka the "Image Source Redirect" vulnerability.
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Analysis
by VulDB Data Team • 05/29/2025
The CVE-2000-0156 vulnerability represents a critical security flaw in Internet Explorer versions 4.x and 5.x that fundamentally undermines the browser's security model through improper handling of image source redirection. This vulnerability operates by exploiting the browser's trust relationship with web servers, allowing remote attackers to manipulate the image loading mechanism to access files outside of the intended security domain. The flaw specifically targets the way Internet Explorer processes the src attribute in html img tags when the image source is redirected through a web server, creating an avenue for unauthorized file access.
The technical implementation of this vulnerability leverages the browser's handling of HTTP redirects and relative path resolution in image loading contexts. When a web server responds to an image request with an HTTP redirect to a different location, Internet Explorer's image loading component fails to properly validate the destination path against the original security boundaries. This allows an attacker-controlled web server to redirect image requests to arbitrary local file paths on the victim's machine, potentially accessing sensitive files such as configuration data, temporary files, or other resources that should remain protected from web-based access. The vulnerability stems from insufficient input validation and path sanitization within the browser's image processing pipeline, creating a direct path traversal condition.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable more sophisticated attacks within the context of a compromised browser session. Attackers can leverage this flaw to access local files that might contain sensitive data, credentials, or system information that could be exfiltrated to the attacking server. The vulnerability is particularly concerning because it operates within the normal browsing context without requiring any special privileges or user interaction beyond visiting a malicious web page. This makes it an attractive target for phishing campaigns, drive-by downloads, and other social engineering attacks where the attacker can craft malicious web content to exploit the vulnerability automatically. The flaw essentially breaks the fundamental security boundary between web content and local system resources.
Mitigation strategies for CVE-2000-0156 primarily focus on browser upgrades and security configuration changes that address the core issue of improper path validation in image loading operations. Users should immediately upgrade to newer versions of Internet Explorer that have corrected this vulnerability, as Microsoft released patches and updated versions that properly validate image source paths against security boundaries. Network administrators should implement web content filtering solutions that can detect and block suspicious image redirection patterns, though this represents a secondary mitigation approach. The vulnerability aligns with CWE-22 Path Traversal and CWE-74 Injection flaws, demonstrating how improper input validation can lead to unauthorized access. From an ATT&CK framework perspective, this vulnerability maps to T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation, as it enables attackers to execute unauthorized file access operations within the victim's security context. Organizations should also implement browser security policies that restrict image loading from untrusted sources and consider implementing additional network-level protections to prevent exploitation attempts.