CVE-2003-0300 in Sylpheed
Summary
by MITRE
The IMAP Client for Sylpheed 0.8.11 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 • 06/14/2018
The vulnerability identified as CVE-2003-0300 affects the IMAP client component of Sylpheed version 0.8.11, representing a critical denial of service weakness that can be exploited by remote attackers through malicious IMAP servers. This issue stems from insufficient input validation mechanisms within the client's handling of literal size values during IMAP protocol communication, creating a pathway for attackers to disrupt normal email client operations. The vulnerability specifically targets the client's parsing logic for IMAP literal data transfers, where improperly handled numeric values can lead to system instability and complete application termination.
The technical flaw manifests through integer signedness errors and integer overflow conditions that occur when the Sylpheed IMAP client processes large literal size values sent by malicious servers. These errors typically arise when unsigned integer values are improperly converted to signed integers or when arithmetic operations exceed the maximum representable values for the integer data types used in the application's memory management. The vulnerability falls under CWE-190, which categorizes integer overflow and underflow conditions, and specifically relates to CWE-191, which addresses signed integer overflow conditions. When these conditions occur during IMAP literal processing, the application's memory management structures become corrupted, leading to unpredictable behavior and eventual application crash.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged by attackers to systematically disable email client functionality across affected systems. An attacker controlling a malicious IMAP server can craft specially formatted responses that contain oversized literal size values, causing the vulnerable Sylpheed client to crash and terminate its IMAP session. This creates a persistent denial of service condition that prevents users from accessing their email accounts through the compromised client, effectively blocking legitimate email communication. The vulnerability is particularly concerning in enterprise environments where email clients may be automatically configured to connect to multiple IMAP servers, potentially allowing a single malicious server to compromise multiple client instances.
Mitigation strategies for this vulnerability involve immediate patching of the Sylpheed client to version 0.8.12 or later, which contains fixes for the integer overflow and signedness handling issues. Organizations should also implement network-level filtering to restrict access to potentially malicious IMAP servers, particularly in environments where email clients are configured to connect to external servers without proper verification. From a defensive perspective, this vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a classic example of how protocol parsing vulnerabilities can be exploited to achieve system compromise. System administrators should also consider implementing intrusion detection systems that can monitor for unusual IMAP literal size patterns, as these may indicate attempts to exploit the vulnerability. Additionally, the incident highlights the importance of input validation and proper integer handling in client applications, emphasizing the need for comprehensive testing of boundary conditions in protocol implementations.