CVE-2005-4695 in Brightmail AntiSpam
Summary
by MITRE
Symantec Brightmail AntiSpam 6.0 build 1 and 2 allows remote attackers to cause a denial of service (bmserver component termination) via malformed MIME messages.
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Analysis
by VulDB Data Team • 06/26/2025
The vulnerability identified as CVE-2005-4695 affects Symantec Brightmail AntiSpam version 6.0 build 1 and 2, specifically targeting the bmserver component that handles email processing and spam filtering operations. This issue represents a critical denial of service weakness that can be exploited by remote attackers without requiring authentication or privileged access. The vulnerability stems from insufficient input validation mechanisms within the email processing pipeline, particularly when handling malformed MIME messages that contain malformed headers or invalid encoding sequences. The affected system exhibits a complete termination of the bmserver process when encountering these specially crafted email payloads, effectively disrupting email services for all users within the organization's email infrastructure.
The technical flaw manifests as a buffer overflow or improper state handling within the MIME parsing routines of the Brightmail server component. When the bmserver processes incoming emails containing malformed MIME structures, the parsing logic fails to properly validate or sanitize the message content, leading to an uncontrolled termination of the service process. This behavior aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which covers stack-based buffer overflow scenarios. The vulnerability is particularly dangerous because it can be triggered through standard email transmission without requiring any special privileges or access credentials, making it an attractive target for malicious actors seeking to disrupt email services.
The operational impact of this vulnerability extends beyond simple service disruption, as it can lead to complete email service outages that affect business communications and productivity across organizations relying on Symantec Brightmail for email security. Email delivery delays or complete failures can result in missed critical communications, potential financial losses, and damage to organizational reputation. The vulnerability affects the availability aspect of the CIA triad by compromising the system's ability to provide continuous email services. Organizations may experience cascading effects as email-dependent business processes halt, and IT teams must respond to service interruptions while potentially dealing with increased spam volumes as attackers exploit the service disruption to send more unsolicited messages.
Mitigation strategies should focus on immediate patch application from Symantec to address the underlying parsing logic flaws in the bmserver component. Network administrators should implement email filtering rules that can detect and quarantine malformed MIME messages before they reach the vulnerable server components. Additionally, implementing redundant email processing systems and load balancing can help maintain service availability during exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1499.004, which covers "Endpoint Denial of Service," and T1595.001, related to "Active Scanning" techniques that attackers might use to identify vulnerable systems. Organizations should also consider implementing intrusion detection systems that can monitor for unusual patterns of email traffic or service termination events that may indicate exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify similar parsing vulnerabilities in other email security solutions within the organization's infrastructure.