CVE-2003-0852 in Sylpheed
Summary
by MITRE
Format string vulnerability in send_message.c for Sylpheed-claws 0.9.4 through 0.9.6 allows remote SMTP servers to cause a denial of service (crash) in sylpheed via format strings in an error message.
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Analysis
by VulDB Data Team • 06/15/2018
The vulnerability identified as CVE-2003-0852 represents a critical format string flaw within the Sylpheed-claws email client version 0.9.4 through 0.9.6. This issue specifically affects the send_message.c component which handles SMTP communication with remote mail servers. The vulnerability stems from improper input validation and handling of error messages received from SMTP servers during the message sending process. When a remote SMTP server responds with malformed error messages containing format specifiers, the client application fails to properly sanitize this input before using it in printf-style functions, creating an exploitable condition that can be leveraged by malicious actors.
This format string vulnerability operates at the core of application security principles and aligns with CWE-134, which describes the weakness of using user-supplied data in format string functions without proper validation. The technical flaw manifests when the sylpheed-claws client receives an error message from an SMTP server that contains format specifiers such as %s, %d, or other printf-style formatting characters. These specifiers are then directly passed to format string functions without appropriate sanitization or escaping, allowing attackers to manipulate the execution flow of the application. The vulnerability specifically targets the client's handling of error responses from remote mail servers, making it particularly dangerous in networked email environments where clients frequently communicate with potentially untrusted SMTP servers.
The operational impact of this vulnerability extends beyond simple denial of service, as it represents a fundamental security weakness that can be exploited for more sophisticated attacks. When exploited successfully, the vulnerability causes the sylpheed-claws client to crash and terminate unexpectedly, effectively creating a denial of service condition that prevents users from sending email messages through the affected client. This disruption can be particularly damaging in enterprise environments where email communication is critical for business operations. The vulnerability also demonstrates the importance of proper input validation and the principle of least privilege in application design, as it shows how untrusted input from network communications can be weaponized to compromise application stability.
Mitigation strategies for this vulnerability require immediate application of security patches provided by the software vendor, as the issue affects multiple versions of the Sylpheed-claws client. Organizations should implement network segmentation and monitoring to detect unusual SMTP traffic patterns that might indicate exploitation attempts. The fix involves ensuring that all user-supplied input, particularly error messages from external servers, is properly sanitized before being used in format string functions. Security practitioners should also consider implementing intrusion detection systems that can identify potential format string exploitation attempts and establish network policies that limit direct SMTP communication from untrusted sources. This vulnerability underscores the importance of following secure coding practices and adheres to ATT&CK technique T1203, which covers the use of format string vulnerabilities for denial of service and potential privilege escalation attacks. The remediation process should include comprehensive code review to identify similar patterns in other parts of the application and implementation of automated testing procedures to validate input handling before deployment in production environments.