CVE-2005-1213 in Outlook Express
Summary
by MITRE
Stack-based buffer overflow in the news reader for Microsoft Outlook Express (MSOE.DLL) 5.5 SP2, 6, and 6 SP1 allows remote malicious NNTP servers to execute arbitrary code via a LIST response with a long second field.
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Analysis
by VulDB Data Team • 07/04/2025
The vulnerability identified as CVE-2005-1213 represents a critical stack-based buffer overflow flaw within Microsoft Outlook Express news reader component known as MSOE.DLL. This vulnerability affects multiple versions including Outlook Express 5.5 Service Pack 2, version 6, and version 6 Service Pack 1, making it a significant concern for organizations relying on these email clients for news group communications. The flaw resides in how the application processes NNTP (Network News Transfer Protocol) responses, specifically when handling the LIST command response which is commonly used to retrieve newsgroup listings from news servers.
The technical exploitation mechanism involves a malicious NNTP server crafting a specially formatted LIST response where the second field contains an excessively long string of data. When Outlook Express processes this malformed response, the MSOE.DLL component fails to properly validate the input length, causing the data to overflow the allocated stack buffer space. This buffer overflow condition occurs because the application does not implement proper bounds checking for the second field of the LIST response, allowing an attacker to overwrite adjacent memory locations on the stack. The overflow can potentially overwrite the return address of the function executing the LIST response processing, enabling remote code execution with the privileges of the user running Outlook Express.
The operational impact of this vulnerability extends beyond simple remote code execution, as it can be leveraged for privilege escalation and system compromise within the victim's environment. Attackers can craft malicious NNTP servers that respond to LIST commands with oversized second fields, effectively creating a remote exploitation vector that does not require user interaction beyond normal news group browsing. The vulnerability affects the core functionality of Outlook Express news reader, making it particularly dangerous as users may unknowingly connect to compromised news servers while accessing public or shared newsgroups. This attack vector aligns with ATT&CK technique T1203 for Exploitation for Execution and T1068 for Exploitation for Privilege Escalation, demonstrating how buffer overflow vulnerabilities can be weaponized for broader system compromise.
Microsoft addressed this vulnerability through security updates that included proper input validation for NNTP LIST response processing and enhanced bounds checking within the MSOE.DLL component. Organizations should implement network segmentation to prevent access to untrusted NNTP servers and ensure all systems receive timely security patches. The vulnerability demonstrates the importance of proper input validation in network protocol implementations and aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient space is allocated for data. System administrators should consider disabling news group functionality in Outlook Express when not required and monitor for unauthorized NNTP server connections. The attack scenario highlights the need for defense-in-depth strategies that include network monitoring, application whitelisting, and regular security assessments to identify similar buffer overflow vulnerabilities in legacy applications.