CVE-2001-0945 in Outlook Express
Summary
by MITRE
Buffer overflow in Outlook Express 5.0 through 5.02 for Macintosh allows remote attackers to cause a denial of service via an e-mail message that contains a long line.
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Analysis
by VulDB Data Team • 05/16/2019
The vulnerability identified as CVE-2001-0945 represents a classic buffer overflow flaw affecting Microsoft Outlook Express versions 5.0 through 5.02 on Macintosh platforms. This security weakness stems from inadequate input validation mechanisms within the email client's parsing routines, specifically when processing email messages containing excessively long lines of text. The flaw operates by exploiting the limited buffer size allocated for handling email content, where maliciously crafted messages can exceed these boundaries and overwrite adjacent memory segments.
The technical implementation of this vulnerability falls under the Common Weakness Enumeration category CWE-121, which classifies buffer overflow conditions that occur when a program writes data beyond the allocated buffer limits. In the context of Outlook Express 5.x for Macintosh, the application fails to properly validate the length of lines within email messages before processing them, creating an exploitable condition where an attacker can craft a message containing a line exceeding the buffer capacity. This overflow can occur during the parsing of email headers or body content, particularly when encountering long lines that surpass the predetermined buffer size limits.
The operational impact of this vulnerability manifests primarily as a denial of service condition rather than arbitrary code execution. When a victim user opens a maliciously crafted email message, the buffer overflow causes the application to crash or become unresponsive, effectively rendering the email client unusable until manually restarted. This denial of service scenario can be particularly disruptive in environments where Outlook Express serves as the primary email client, potentially affecting business communications and productivity. The vulnerability is particularly concerning because it requires no special privileges or authentication from the attacker, making it a straightforward remote attack vector.
Mitigation strategies for CVE-2001-0945 should focus on both immediate defensive measures and long-term remediation approaches. The most effective immediate solution involves updating to a patched version of Outlook Express or migrating to a more secure email client platform, as Microsoft released updates addressing this specific vulnerability. Network administrators should implement email filtering rules to identify and quarantine messages containing unusually long lines or suspicious content patterns. Additionally, system hardening measures including limiting email client privileges and implementing sandboxing techniques can reduce the potential impact of exploitation attempts. The vulnerability also highlights the importance of input validation and boundary checking in application development, aligning with defensive programming practices recommended by the software security community. Organizations should also consider implementing email security appliances or services that can detect and block malicious email content before it reaches end-user systems. From an ATT&CK framework perspective, this vulnerability maps to techniques involving denial of service and initial access through social engineering, as attackers must successfully deliver the malicious email to trigger the exploit.