CVE-2006-0504 in MailEnable Enterprise
Summary
by MITRE
Unspecified vulnerability in MailEnable Enterprise Edition before 1.2 allows remote attackers to cause a denial of service (CPU utilization) by viewing "formatted quoted-printable emails" via webmail.
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Analysis
by VulDB Data Team • 06/13/2019
The vulnerability identified as CVE-2006-0504 represents a significant security flaw in MailEnable Enterprise Edition version 1.2 and earlier, specifically affecting the webmail component's handling of email formatting. This issue manifests as a remote denial of service condition that can be exploited by attackers without requiring authentication or privileged access to the system. The vulnerability occurs during the processing of formatted quoted-printable emails, which are commonly used in email systems to encode binary data for transmission across internet protocols. The affected system exhibits abnormal CPU utilization patterns when attempting to render these specific email formats, leading to system performance degradation and potential service interruption.
From a technical perspective, this vulnerability stems from inadequate input validation and processing within the webmail interface of MailEnable Enterprise Edition. When the system encounters a specially crafted quoted-printable email message, the parsing and rendering engine fails to properly handle the formatting, resulting in excessive computational overhead. The root cause lies in how the application processes the quoted-printable encoding, which is a standard method for encoding binary data in email messages to ensure compatibility with 7-bit transport protocols. This particular implementation flaw creates a condition where malformed or specially constructed quoted-printable content triggers resource-intensive processing loops that consume CPU cycles disproportionately to the legitimate email content.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the overall availability and reliability of email services. Attackers can exploit this weakness by sending specifically crafted emails to the target system, causing sustained high CPU utilization that may render the webmail service unavailable to legitimate users. The vulnerability affects the enterprise edition of MailEnable, suggesting that organizations relying on this platform for business communications face potential operational risks, including email service outages, degraded performance, and possible business continuity impacts. The remote nature of the attack means that adversaries can exploit this flaw from outside the network perimeter, making it particularly dangerous for organizations that do not implement proper network segmentation or email filtering mechanisms.
Organizations affected by this vulnerability should implement immediate mitigation strategies to protect their email infrastructure. The primary recommendation involves upgrading to MailEnable Enterprise Edition 1.2 or later, which includes patches specifically designed to address the quoted-printable email processing flaw. Additionally, implementing email filtering rules that identify and block suspicious email formats can provide interim protection while the upgrade process is underway. Network monitoring should be enhanced to detect unusual CPU utilization patterns that may indicate exploitation attempts, and security teams should establish incident response procedures to address potential denial of service events. This vulnerability aligns with CWE-400, which categorizes "Uncontrolled Resource Consumption" as a common weakness in software systems, and maps to ATT&CK technique T1499.004, which covers "Endpoint Denial of Service" through resource exhaustion attacks. The broader implications suggest that organizations should conduct comprehensive vulnerability assessments of their email infrastructure and establish regular patch management procedures to prevent similar issues from compromising service availability.