CVE-2008-1691 in SLMail Pro
Summary
by MITRE
Unspecified vulnerability in SLMail.exe in SLMail Pro 6.3.1.0 and earlier allows remote attackers to cause a denial of service (UDP service outage) via a large packet to UDP port 54. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 05/31/2025
The vulnerability identified as CVE-2008-1691 represents a critical denial of service weakness within the SLMail email server software version 6.3.1.0 and earlier releases. This flaw specifically affects the UDP service component of the SLMail Pro email server, which operates on UDP port 54. The vulnerability manifests when the SLMail.exe process receives a malformed or excessively large UDP packet on this designated port, leading to a complete service outage that can disrupt email communication for affected systems. This issue falls under the category of input validation failures and represents a classic buffer overflow or memory corruption vulnerability that occurs during packet processing.
The technical exploitation of this vulnerability involves sending a specially crafted UDP packet of significant size to port 54, which triggers an unhandled exception or memory corruption within the SLMail.exe process. This results in the termination of the UDP service, leaving the email server unable to process incoming UDP traffic on that port. The vulnerability demonstrates poor error handling and insufficient input sanitization within the SLMail software architecture, particularly in how it processes network packets received through the UDP protocol. This weakness is categorized as a buffer overflow condition that occurs during network packet parsing, which is a well-documented pattern in software security vulnerabilities and aligns with CWE-121 buffer overflow conditions.
The operational impact of this vulnerability extends beyond simple service disruption, as it can effectively render email services unavailable to legitimate users and can be exploited as part of broader network attack campaigns. Organizations relying on SLMail Pro for email services face potential business disruption when this vulnerability is exploited, particularly in environments where email availability is critical for operations. The vulnerability affects systems where SLMail Pro is installed and configured to accept UDP traffic on port 54, which could include various email server configurations in corporate and enterprise environments. This vulnerability can be leveraged by attackers to perform service disruption attacks, potentially as part of larger campaigns targeting network availability or as a stepping stone for more sophisticated attacks.
Security professionals should note that this vulnerability represents a significant risk for systems that have not been updated with the latest security patches from SLMail. The exploitation requires minimal technical skill and can be automated, making it particularly dangerous for organizations that have not implemented proper network segmentation or firewall rules to restrict UDP traffic. Mitigation strategies should include immediate patching of the SLMail software to version 6.3.2.0 or later, which contains fixes for this vulnerability. Network administrators should also implement firewall rules to block UDP traffic on port 54 from untrusted networks and consider disabling UDP services if they are not required for business operations. This vulnerability aligns with ATT&CK technique T1499.004 for network denial of service and represents a clear example of how insufficient input validation can lead to service disruption attacks. Organizations should also conduct thorough vulnerability assessments to identify any other instances of similar buffer overflow conditions in their email server infrastructure and ensure proper monitoring for exploitation attempts.