CVE-2001-0340 in Exchange
Summary
by MITRE
An interaction between the Outlook Web Access (OWA) service in Microsoft Exchange 2000 Server and Internet Explorer allows attackers to execute malicious script code against a user s mailbox via a message attachment that contains HTML code, which is executed automatically.
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Analysis
by VulDB Data Team • 10/07/2025
This vulnerability exists within the interaction between Microsoft Exchange 2000 Server's Outlook Web Access service and Internet Explorer browsers. The flaw arises from insufficient input validation and sanitization of HTML content within email attachments processed through the web-based email interface. When a user accesses their mailbox through OWA and encounters a malicious email attachment containing specially crafted HTML code, the browser automatically executes this code without proper security restrictions. This represents a classic cross-site scripting vulnerability that leverages the trust relationship between the web client and the email service. The vulnerability is categorized under CWE-79 as improper neutralization of input during web output, specifically manifesting as a client-side script execution flaw. From an operational perspective, this vulnerability allows attackers to perform arbitrary actions on behalf of authenticated users, potentially leading to complete mailbox compromise, data exfiltration, and privilege escalation within the email environment.
The technical exploitation of this vulnerability requires an attacker to craft a malicious email attachment with embedded HTML code that triggers script execution when viewed through the OWA interface. The attack vector specifically targets the HTML rendering engine of Internet Explorer when processing email content through the web-based interface. This creates a persistent threat where users who access their mailboxes through OWA become potential victims of automated script execution. The vulnerability is particularly dangerous because it operates within the context of a trusted service, allowing attackers to bypass traditional email filtering mechanisms since the malicious code is embedded within legitimate-looking email attachments. The attack follows the ATT&CK technique T1059.007 for scripting languages, specifically targeting the command and scripting interpreter category. The flaw essentially allows for a form of privilege escalation where a user's session context is exploited to execute malicious code with the privileges of the authenticated user.
The operational impact of this vulnerability extends beyond simple script execution to encompass complete mailbox compromise and potential network infiltration. Attackers can leverage this vulnerability to read, modify, or delete email messages, access calendar information, and potentially escalate privileges to gain administrative access to the Exchange server itself. The vulnerability creates a persistent threat vector that can be exploited repeatedly against any user accessing their mailbox through the affected OWA service. Organizations with Exchange 2000 servers running OWA are particularly vulnerable since this service was widely deployed in enterprise environments during that timeframe. The attack scenario typically involves sending a carefully crafted email to a target user, who then accesses their mailbox through OWA, triggering the automatic execution of malicious code. This vulnerability directly impacts the confidentiality, integrity, and availability of email services, representing a significant security risk for organizations relying on Exchange 2000 Server with OWA functionality.
Mitigation strategies for this vulnerability primarily focus on implementing proper input validation and output encoding for HTML content within web-based email services. Organizations should ensure that all email attachments are properly sanitized before being processed by the web interface, implementing strict content filtering rules that prevent execution of embedded scripts. The recommended approach includes disabling automatic HTML rendering for email attachments, implementing proper web application security controls, and ensuring that users access email services through secure protocols. Microsoft released patches and updates to address this vulnerability, emphasizing the importance of timely security updates for enterprise email systems. Network segmentation and access controls should be implemented to limit the potential impact of successful exploitation. The mitigation approach aligns with the ATT&CK technique T1566.001 for phishing and T1071.004 for application layer protocol usage. Regular security assessments should be conducted to identify similar vulnerabilities in legacy systems, particularly focusing on outdated web-based email services that may contain similar rendering engine flaws. Organizations should also implement user education programs to raise awareness about the dangers of opening suspicious email attachments through web-based interfaces.