CVE-2005-0456 in Web Browser
Summary
by MITRE
Opera 7.54 and earlier does not properly validate base64 encoded binary data in a data: (RFC 2397) URL, which causes the URL to be obscured in a download dialog, which may allow remote attackers to trick users into executing arbitrary code.
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Analysis
by VulDB Data Team • 11/21/2024
The vulnerability described in CVE-2005-0456 represents a critical security flaw in Opera web browser versions 7.54 and earlier that stems from improper validation of base64 encoded binary data within data URIs as defined by RFC 2397. This weakness specifically affects how the browser handles data: URLs that contain embedded binary content encoded in base64 format, creating a significant vector for social engineering attacks and potential code execution. The flaw resides in the browser's handling of the download dialog interface where maliciously crafted data URIs can obscure the true nature of the content being downloaded.
The technical implementation of this vulnerability exploits the browser's insufficient input validation mechanisms for base64 encoded data within data: URLs. When Opera encounters a data URI containing base64 encoded binary content, it fails to properly sanitize or validate the encoded data before displaying it in the download dialog. This validation failure allows attackers to craft malicious URLs where the displayed filename or content type in the download dialog does not accurately reflect the actual binary payload being downloaded. The base64 encoding process creates a deceptive layer where legitimate-looking filenames can mask malicious executables or scripts.
From an operational perspective, this vulnerability enables sophisticated phishing and social engineering attacks where attackers can craft data: URLs that appear benign in the download dialog but actually deliver malicious payloads. The obscuring effect means users cannot accurately determine whether they are downloading legitimate content or potentially harmful executables, making this a particularly dangerous flaw for user deception. Attackers can exploit this by creating URLs that display innocuous filenames while actually delivering malware, exploit code, or other malicious binaries that execute upon user interaction with the downloaded file.
The impact of this vulnerability extends beyond simple deception as it creates a pathway for arbitrary code execution through user interaction with the downloaded content. This aligns with attack patterns documented in the ATT&CK framework under initial access and execution techniques where adversaries leverage user trust and interface manipulation to bypass security controls. The vulnerability also maps to CWE-20, which describes improper input validation, and CWE-345, which covers insufficient verification of data authenticity. The weakness fundamentally undermines the browser's security model by allowing attackers to manipulate user interface elements that should provide security warnings or clear identification of content risks.
Mitigation strategies for this vulnerability require immediate browser updates to patched versions that properly validate base64 encoded data within data: URLs. Organizations should implement network-level filtering to block or monitor data: URLs that contain suspicious patterns or originate from untrusted sources. Browser security configurations should be adjusted to disable or restrict data: URI handling when possible, and users should be educated about the risks of downloading files from unknown or untrusted sources. The vulnerability demonstrates the importance of proper input validation in security-critical applications and highlights how seemingly minor interface flaws can create significant attack vectors. Security professionals should also consider implementing additional monitoring for unusual data URI usage patterns in network traffic analysis to detect potential exploitation attempts.