CVE-2005-1013 in Professional Edition
Summary
by MITRE
The SMTP service in MailEnable Enterprise 1.04 and earlier and Professional 1.54 and earlier allows remote attackers to cause a denial of service (server crash) via an EHLO command with a Unicode string.
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Analysis
by VulDB Data Team • 07/09/2019
The vulnerability identified as CVE-2005-1013 affects the SMTP service implementation within MailEnable Enterprise 1.04 and earlier versions, as well as MailEnable Professional 1.54 and earlier releases. This represents a classic denial of service weakness that exploits improper input validation within the email server's command processing mechanism. The specific flaw manifests when the SMTP service receives an EHLO command containing a Unicode string, which triggers an unhandled exception leading to service termination and complete server crash. This vulnerability operates at the application layer of the network stack, specifically targeting the Simple Mail Transfer Protocol implementation that governs email server communications.
The technical root cause of this vulnerability stems from inadequate string handling and buffer management within the MailEnable SMTP service code. When processing the EHLO command, the system fails to properly sanitize or validate Unicode input sequences, allowing maliciously crafted Unicode characters to bypass normal processing routines. This weakness aligns with CWE-129, which describes improper validation of array indices or string lengths, and CWE-170, which addresses issues with improper handling of Unicode characters. The vulnerability creates a condition where the server's memory management routines encounter unexpected Unicode byte sequences that cause memory corruption or stack overflow conditions, ultimately resulting in the service process crashing and rendering the email server unavailable to legitimate users.
From an operational perspective, this vulnerability presents a significant risk to email server availability and business continuity. Attackers can exploit this weakness to remotely disrupt email services without requiring authentication or special privileges, making it particularly dangerous for organizations relying on MailEnable for their email infrastructure. The impact extends beyond simple service disruption as it can affect critical business communications, customer support systems, and internal email workflows. The vulnerability's exploitability is high due to the nature of SMTP commands being accessible over standard network ports, and the fact that the attack requires minimal technical expertise to execute successfully. Organizations may experience extended downtime while services are restored, potentially leading to lost productivity and damaged customer relationships.
Mitigation strategies for this vulnerability should focus on immediate patching of affected MailEnable versions to the latest available releases that contain proper input validation routines. System administrators should implement network-level restrictions to limit access to SMTP ports from trusted sources only, while also monitoring for unusual EHLO command patterns that might indicate exploitation attempts. The implementation of intrusion detection systems capable of identifying malformed SMTP commands can provide early warning of potential attacks. Additionally, organizations should consider implementing redundant email services or failover mechanisms to maintain business continuity during potential exploitation events. This vulnerability demonstrates the importance of proper input validation in network services and aligns with ATT&CK technique T1499.004, which covers network denial of service attacks through malformed network traffic. Regular security assessments and vulnerability scanning should be implemented to identify similar weaknesses in other email server implementations and prevent similar incidents from occurring in the future.