CVE-2007-4848 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 4.0 through 7 allows remote attackers to determine the existence of local files that have associated images via a res:// URI in the src property of a JavaScript Image object, as demonstrated by the URI for a bitmap image resource within a (1) .exe or (2) .dll file.
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Analysis
by VulDB Data Team • 07/21/2021
This vulnerability exists in Microsoft Internet Explorer versions 4.0 through 7 and represents a classic information disclosure flaw that leverages the browser's handling of resource URIs. The vulnerability stems from the way Internet Explorer processes res:// URIs within JavaScript Image objects, allowing remote attackers to perform file system enumeration by attempting to load images from local files that are embedded within executable binaries. This technique exploits the browser's inability to properly validate or restrict access to local resources when they are referenced through the resource protocol.
The technical mechanism involves constructing a res:// URI that points to embedded image resources within .exe or .dll files, then using JavaScript to create an Image object with this URI in the src property. When the browser attempts to load the image, it reveals whether the specified resource exists within the binary file structure, effectively creating a side-channel information leak. This allows attackers to determine the presence of specific files on the target system without direct access to the file system, as demonstrated by the ability to detect embedded bitmap resources within executable files.
The operational impact of this vulnerability extends beyond simple file enumeration, as it provides attackers with valuable reconnaissance information that can be used to build more sophisticated attacks. An attacker can use this technique to identify the presence of specific software components, potentially uncovering system configurations, version information, or even sensitive embedded resources. This information disclosure can be particularly dangerous when combined with other vulnerabilities, as it enables attackers to tailor subsequent attacks based on the discovered file system structure and available resources.
This vulnerability aligns with CWE-200, which describes information exposure, and represents a form of information leakage through resource handling. The attack pattern follows the ATT&CK technique T1083 for discovering files and directories, as it enables adversaries to enumerate local file system contents through browser-based mechanisms. The vulnerability demonstrates poor input validation and insufficient access controls in the browser's resource loading mechanism, particularly when processing res:// URIs that reference embedded resources within binary files.
Mitigation strategies should focus on restricting access to local resources and implementing proper validation of URI schemes. Browser vendors should ensure that resource protocols are properly sandboxed and that access to embedded resources within executables is appropriately restricted. Users should be advised to avoid visiting untrusted websites and to keep their browsers updated with security patches. The vulnerability also highlights the importance of proper privilege separation in browser implementations, as it demonstrates how web-based attacks can leverage browser internals to gain unauthorized access to local system information. Organizations should implement network-level controls to restrict access to potentially malicious content and ensure that security updates are applied promptly to address such information disclosure vulnerabilities.