CVE-2004-1490 in Web Browser
Summary
by MITRE
Opera 7.54 and earlier allows remote attackers to spoof file types in the download dialog via dots and non-breaking spaces (ASCII character code 160) in the (1) Content-Disposition or (2) Content-Type headers.
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Analysis
by VulDB Data Team • 06/05/2019
This vulnerability exists in Opera web browser versions 7.54 and earlier, where the application fails to properly validate file type information in HTTP response headers. The flaw specifically affects how the browser processes the Content-Disposition and Content-Type headers during file download operations, creating a potential security risk for users who may be misled into executing malicious files. The vulnerability stems from the browser's insufficient sanitization of special characters including dots and non-breaking spaces, which are represented by ASCII character code 160, in download headers.
The technical implementation of this vulnerability allows remote attackers to manipulate the file type detection mechanism by embedding specially crafted characters within the HTTP headers. When Opera processes these headers, it does not adequately filter or normalize the presence of non-breaking spaces and other special characters that can alter how file extensions are interpreted during the download dialog. This creates a scenario where a malicious server can present a file with a misleading extension while actually serving a different file type, potentially fooling users into executing harmful content.
The operational impact of this vulnerability is significant as it enables attackers to perform deception attacks against Opera users. An attacker could host a malicious executable file but present it with a benign file extension such as .pdf or .doc in the download dialog, exploiting the browser's lenient header parsing behavior. This type of attack falls under the category of file type confusion or spoofing attacks, where user trust in file extensions is violated. The vulnerability essentially undermines the browser's ability to properly warn users about potentially dangerous file downloads, creating an environment where social engineering attacks can be more effectively executed.
From a cybersecurity perspective, this vulnerability aligns with CWE-155 which addresses improper handling of special characters and CWE-20 which covers improper input validation. The attack vector can be mapped to ATT&CK technique T1059 where adversaries use legitimate file execution paths to deliver malicious content. The vulnerability demonstrates a classic case of insufficient input sanitization and header validation, where the browser's security model fails to properly validate the integrity of HTTP response headers before presenting download options to users. This issue highlights the importance of proper header parsing and validation in web browsers to prevent misleading file type information from being displayed to end users.
The recommended mitigations include updating to Opera versions that properly handle file type headers and implementing additional validation layers at the network level. Users should avoid downloading files from untrusted sources and should always verify file integrity before execution. Organizations should consider implementing network-based filtering rules that can detect and block suspicious header combinations. The vulnerability also underscores the need for robust input validation in web applications and the importance of adhering to security best practices when handling HTTP headers to prevent similar issues in other browser implementations.