CVE-2004-1768 in Brightmail Antispam
Summary
by MITRE
The character converters in the Spamhunter and Language ID modules for Symantec Brightmail AntiSpam 6.0.1 before patch 132 allow remote attackers to cause a denial of service (crash) via messages with the ISO-8859-10 character set, which is not recognized by the converters.
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Analysis
by VulDB Data Team • 11/21/2024
The vulnerability described in CVE-2004-1768 represents a critical denial of service weakness within Symantec Brightmail AntiSpam version 6.0.1 prior to patch 132. This issue specifically affects the Spamhunter and Language ID modules that are integral components of the email security solution designed to filter spam and identify message languages. The flaw manifests when the system encounters email messages containing the ISO-8859-10 character set, which is a legacy character encoding standard representing the Nordic languages including Danish, Finnish, Norwegian, and Swedish. The vulnerability stems from the absence of proper character set recognition within the system's converter modules, creating a scenario where unrecognized character encodings trigger system instability.
The technical implementation of this vulnerability involves the character conversion process within the spam filtering pipeline. When an email message arrives containing data encoded in ISO-8859-10, the Spamhunter and Language ID modules attempt to process this character set through their internal conversion routines. However, since these modules lack support for ISO-8859-10 encoding, the conversion process fails catastrophically rather than gracefully handling the unrecognized input. This failure mode results in the complete crash of the affected modules, causing the entire anti-spam system to become unavailable. The issue demonstrates a classic lack of input validation and error handling, where the system does not properly account for edge cases in character encoding specifications. This weakness falls under CWE-248, which addresses "Uncaught Exception" conditions, and more specifically relates to CWE-707, "Improper Neutralization of Input During Web Page Generation," when considering the web-based interface aspects of the product.
The operational impact of this vulnerability extends beyond simple system unavailability, creating significant business disruption for organizations relying on Symantec Brightmail for email security. When the system crashes, legitimate email traffic may be delayed or blocked entirely, affecting communication workflows and potentially causing data loss. The remote nature of the attack means that malicious actors can exploit this weakness without requiring physical access to the system or elevated privileges, making it particularly dangerous in networked environments. Organizations may experience cascading failures as the anti-spam system becomes unresponsive, potentially leading to increased spam volume reaching end users and undermining the overall security posture. The vulnerability also creates opportunities for attackers to perform reconnaissance activities, as successful exploitation can be used to confirm the presence of the vulnerable system and potentially identify other attack vectors within the organization's email infrastructure.
Mitigation strategies for CVE-2004-1768 primarily involve applying the vendor-supplied patch 132, which specifically addresses the character set recognition issue in the Spamhunter and Language ID modules. Organizations should also implement network-level filtering to block messages containing known problematic character encodings, though this approach may inadvertently block legitimate messages. System administrators should monitor for unusual crash patterns or service disruptions that may indicate exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date security patches and implementing robust input validation mechanisms within security appliances. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving service disruption and system resource exhaustion, though it specifically maps to the T1499.004 sub-technique related to network denial of service. Organizations should also consider implementing redundant email security systems to provide failover capabilities when such vulnerabilities are present in primary security infrastructure. The incident underscores the critical need for comprehensive testing of character encoding support in security applications, particularly those handling internationalized content, and demonstrates how seemingly minor implementation gaps can create significant operational risks.