CVE-2003-0301 in Outlook Express
Summary
by MITRE
The IMAP Client for Outlook Express 6.00.2800.1106 allows remote malicious IMAP servers to cause a denial of service (crash) via certain large literal size values that cause either integer signedness errors or integer overflow errors.
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Analysis
by VulDB Data Team • 05/03/2019
The vulnerability identified as CVE-2003-0301 represents a critical denial of service weakness in the IMAP Client component of Outlook Express 6.00.2800.1106. This flaw specifically targets the handling of literal size values during IMAP protocol communication, creating a scenario where remote attackers can manipulate server responses to trigger system instability. The vulnerability exists within the client-side processing logic that interprets data from IMAP servers, making it particularly dangerous as it can be exploited through legitimate email communication channels without requiring special privileges or authentication.
The technical implementation of this vulnerability stems from improper handling of integer values during the parsing of IMAP literal data. When the IMAP client receives certain large literal size values from a malicious server, the application fails to properly validate or process these numeric values, leading to either signedness errors or integer overflow conditions. These errors occur in the client's memory management and data parsing routines where unsigned integer values are improperly cast or compared against signed integer variables. The flaw manifests as a buffer overflow or arithmetic overflow that causes the application to crash or become unresponsive, effectively rendering the email client unusable until manual restart or system reboot occurs.
From an operational perspective, this vulnerability creates significant risk for end users and organizations relying on Outlook Express for email communication. The attack vector is particularly insidious because it requires no user interaction beyond normal email processing, making it difficult to detect and prevent. The vulnerability can be exploited through various means including malicious email servers, compromised email accounts, or even through man-in-the-middle attacks that redirect legitimate email traffic to malicious endpoints. The impact extends beyond individual user disruption to potentially affect entire email communication systems within organizations, as users may be unable to access critical email services during exploitation.
The vulnerability aligns with CWE-190, which addresses integer overflow and underflow conditions, and CWE-129, which covers improper validation of array indices and buffer bounds. From the ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers network denial of service attacks, and T1566.002, which involves phishing through email. Organizations should implement immediate mitigations including disabling IMAP functionality in Outlook Express, applying available patches from Microsoft, and implementing email filtering rules that block suspicious literal size values. Network administrators should also consider monitoring for unusual IMAP traffic patterns that might indicate exploitation attempts. The long-term solution requires upgrading to modern email clients that properly validate all incoming data and implement robust input sanitization mechanisms to prevent similar integer handling errors from occurring in future implementations.