CVE-2005-0563 in Exchange
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Microsoft Outlook Web Access (OWA) component in Exchange Server 5.5 allows remote attackers to inject arbitrary web script or HTML via an email message with an encoded javascript: URL ("javAsc
ript:") in an IMG tag.
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Analysis
by VulDB Data Team • 07/04/2025
The vulnerability described in CVE-2005-0563 represents a critical cross-site scripting flaw within Microsoft Outlook Web Access component of Exchange Server 5.5. This security weakness specifically affects the web-based email interface that allows users to access their email accounts through a web browser. The vulnerability stems from inadequate input validation and output encoding mechanisms within the OWA component, creating an exploitable condition where malicious content can be injected into email messages. Attackers can leverage this flaw by crafting specially formatted email messages containing encoded javascript URLs that bypass normal security filters and are subsequently executed in the context of other users' browsers.
The technical implementation of this vulnerability involves the exploitation of HTML parsing and URL decoding mechanisms within the Outlook Web Access interface. When an email message containing an encoded javascript: URL is processed by the OWA component, the system fails to properly sanitize the input before rendering it in the web interface. The specific attack vector utilizes the encoded format "javAsc
ript:" where the hexadecimal encoding and line breaks are designed to evade typical security filters. The IMG tag serves as the delivery mechanism, as web browsers will attempt to load the image source, which contains the malicious javascript code that gets executed in the victim's browser context. This particular encoding technique demonstrates sophisticated evasion capabilities that could bypass basic security measures designed to detect standard javascript: URLs.
The operational impact of this vulnerability extends beyond simple script execution to potentially compromise entire user sessions and enable further attacks. When a victim views the malicious email message in their Outlook Web Access interface, the embedded javascript code executes in their browser session, potentially allowing attackers to steal session cookies, redirect users to malicious sites, or perform actions on behalf of the victim. The vulnerability affects all users who access Exchange Server 5.5 through the web interface, creating a widespread attack surface that could be exploited at scale. This flaw particularly undermines the security of web-based email systems and demonstrates the critical importance of proper input validation in web applications. The attack can be executed remotely without requiring any special privileges or access to the underlying Exchange server infrastructure, making it an attractive target for malicious actors.
Security mitigations for this vulnerability should focus on implementing comprehensive input validation and output encoding mechanisms within the web interface. Organizations should ensure that all user-supplied content is properly sanitized before being rendered in web browsers, with particular attention to URL encoding and HTML tag validation. The implementation of Content Security Policy headers can provide additional protection against script execution, while proper input filtering should prevent the acceptance of encoded javascript URLs in email content. Microsoft addressed this vulnerability through security updates and patches, emphasizing the importance of maintaining current security patches for email server software. This vulnerability aligns with CWE-79, which describes cross-site scripting flaws, and represents a classic example of how web applications must properly encode output to prevent malicious code execution. From an ATT&CK perspective, this vulnerability maps to T1566, which covers social engineering techniques through spearphishing, and T1059, which involves command and scripting interpreter usage, demonstrating how initial access can lead to further exploitation within targeted environments.