CVE-2007-4356 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 6 and 7 embeds FTP credentials in HTML files that are retrieved during an FTP session, which allows context-dependent attackers to obtain sensitive information by reading the HTML source, as demonstrated by a (1) .htm, (2) .html, or (3) .mht file.
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Analysis
by VulDB Data Team • 04/07/2017
Microsoft Internet Explorer versions 6 and 7 contained a critical information disclosure vulnerability that emerged from how the browser handled FTP authentication credentials within HTML documents. This flaw originated from the browser's implementation of the File Transfer Protocol where user credentials were inadvertently embedded in HTML source code during FTP sessions. The vulnerability specifically affected web pages with extensions .htm, .html, and .mht that were retrieved from FTP servers, creating a persistent security risk that could be exploited by context-dependent attackers. The technical mechanism behind this vulnerability involved the browser's automatic inclusion of FTP credentials in the HTML source code, which occurred when the browser processed and rendered content from FTP sources. This behavior violated fundamental security principles by exposing authentication information that should remain confidential during network operations. The flaw was categorized under CWE-200, which addresses "Information Exposure" and specifically relates to the improper exposure of sensitive information. From an operational perspective, this vulnerability enabled attackers to obtain sensitive information by simply reading the HTML source code of affected files, potentially compromising user credentials and access privileges to FTP resources. The attack vector was particularly concerning because it required minimal technical expertise to exploit, making it accessible to a broad range of threat actors. The vulnerability aligned with ATT&CK technique T1552.001, which covers "Credentials In Files" and represents a common method for credential harvesting in web-based attacks. The impact extended beyond simple information disclosure as it could lead to unauthorized access to protected FTP resources and potential lateral movement within networks that relied on FTP protocols for file transfers. The security implications were exacerbated by the widespread adoption of Internet Explorer 6 and 7, which meant that a large user base was potentially exposed to this vulnerability. Organizations running these browser versions faced significant risk of credential compromise, particularly in environments where FTP services were commonly used for file sharing and resource access. The vulnerability demonstrated the importance of proper credential handling in web browsers and highlighted the need for secure implementation of network protocols. This flaw represented a fundamental breakdown in the separation between user authentication and document rendering, creating a persistent exposure window for sensitive credentials. The issue was particularly problematic in corporate environments where FTP servers might contain sensitive organizational data, making the potential impact of credential exposure significantly more severe. Security professionals needed to understand that this vulnerability could be exploited through simple document viewing activities, meaning that users could inadvertently expose their credentials merely by accessing certain web content. The remediation required immediate browser updates and patches from Microsoft, while organizations needed to implement network monitoring to detect potential credential exposure. This vulnerability also underscored the importance of secure coding practices in browser development, particularly around credential handling and information flow management. The flaw contributed to the broader understanding of how web browsers could inadvertently expose sensitive information during routine operations, influencing future security design principles in web application development. Organizations needed to consider the long-term implications of such vulnerabilities, as they could persist even after initial exploitation attempts, creating ongoing security risks for affected systems. The vulnerability also highlighted the necessity of comprehensive security testing for browser implementations, particularly focusing on how authentication information was handled during various network operations. This issue ultimately reinforced the critical importance of maintaining up-to-date browser software and implementing robust credential management practices to prevent unauthorized access to network resources.