CVE-2005-1931 in GoodTech SMTP Server
Summary
by MITRE
GoodTech SMTP Server 5.14 allows remote attackers to cause a denial of service (application crash) via a RCPT TO command with an invalid argument, as demonstrated using an "A" character.
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Analysis
by VulDB Data Team • 06/06/2019
The vulnerability identified as CVE-2005-1931 affects the GoodTech SMTP Server version 5.14, representing a critical denial of service weakness that can be exploited by remote attackers to disrupt email services. This flaw specifically manifests when the server processes RCPT TO commands with malformed arguments, particularly when an "A" character is used as the argument. The vulnerability falls under the category of improper input validation, where the server fails to properly sanitize or reject malformed email recipient commands that could lead to application instability.
The technical implementation of this vulnerability stems from the server's insufficient error handling mechanisms during SMTP protocol processing. When the GoodTech SMTP Server receives an RCPT TO command with an invalid argument such as a single "A" character, the application fails to properly validate the input before attempting to process it. This lack of input sanitization causes the server to enter an undefined state where it cannot properly handle the malformed command, resulting in a complete application crash and subsequent denial of service for legitimate email traffic. The flaw demonstrates poor defensive programming practices where the system does not implement adequate exception handling or input validation routines that would normally prevent such malformed data from causing system instability.
The operational impact of this vulnerability extends beyond simple service disruption as it can be exploited by malicious actors to systematically degrade email services within organizations relying on the GoodTech SMTP Server. Attackers can repeatedly send malformed RCPT TO commands to cause repeated crashes, potentially leading to extended periods of email service unavailability that can severely impact business operations and communication workflows. This vulnerability directly affects the availability aspect of the CIA triad and represents a classic example of a resource exhaustion attack where the server's processing capabilities are consumed in a way that prevents legitimate service delivery. The impact is particularly severe in environments where email is critical for business operations, as the denial of service can cascade into broader operational disruptions.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and error handling mechanisms within the SMTP server configuration. Organizations should immediately apply the vendor-provided patches or updates that address the specific input validation flaw in the RCPT TO command processing. System administrators should also consider implementing network-level filtering to detect and block malformed SMTP commands before they reach the vulnerable server. Additionally, the implementation of robust logging and monitoring systems can help identify exploitation attempts and provide early warning of potential attacks. From a cybersecurity framework perspective, this vulnerability aligns with CWE-20, which describes improper input validation, and represents a common weakness that can be addressed through proper defensive programming techniques and adherence to secure coding standards. The ATT&CK framework categorizes this as a denial of service technique that can be used to compromise system availability and may be part of broader attack campaigns targeting email infrastructure. Organizations should also consider implementing redundant email services and failover mechanisms to ensure business continuity in the event of successful exploitation attempts.