CVE-2017-6324 in Messaging Gateway
Summary
by MITRE
The Symantec Messaging Gateway, when processing a specific email attachment, can allow a malformed or corrupted Word file with a potentially malicious macro through despite the administrator having the 'disarm' functionality enabled. This constitutes a 'bypass' of the disarm functionality resident to the application.
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Analysis
by VulDB Data Team • 12/29/2020
The Symantec Messaging Gateway represents a critical security appliance designed to protect email environments from malicious content through automated analysis and sanitization processes. This vulnerability specifically targets the gateway's handling of Microsoft Word documents within email attachments, creating a significant bypass of the system's core protective mechanisms. The flaw manifests when the messaging gateway processes a malformed or corrupted Word file that contains a potentially malicious macro, despite the administrator having explicitly enabled the 'disarm' functionality. This represents a fundamental failure in the application's content inspection and sanitization protocols, as the system should have neutralized any macro-enabled content through its built-in disarm capabilities.
The technical nature of this vulnerability stems from the gateway's insufficient validation and sanitization processes for malformed Office documents. When processing email attachments, the system's disarm functionality is designed to remove or neutralize potentially dangerous elements such as macros, embedded scripts, and other executable content that could compromise the email environment. However, this vulnerability allows certain corrupted Word files to bypass these protective measures, enabling the malicious macro to pass through undetected. The flaw likely resides in the document parsing logic where the system fails to properly identify and handle malformed file structures that could contain hidden or obfuscated malicious code within the document's metadata or corrupted sections.
The operational impact of this vulnerability extends beyond simple bypass of security controls, creating a significant risk vector for email-based attacks. Attackers could exploit this weakness by crafting specifically malformed Word documents that appear legitimate to the email gateway but contain embedded macros designed to execute malicious payloads when opened by recipients. This creates a persistent threat where even organizations with properly configured security measures could experience compromise through seemingly routine email traffic. The vulnerability effectively undermines the trust model of the messaging gateway, as administrators who rely on the disarm functionality to protect their environments may unknowingly allow malicious content to reach end users. This bypass could potentially lead to phishing attacks, credential theft, or the deployment of malware across the network through email channels.
Security professionals should consider this vulnerability in the context of broader email security frameworks and incident response protocols. The flaw aligns with CWE-252, which addresses the lack of checks for security-relevant conditions, and represents a failure in the principle of least privilege where potentially dangerous content should be neutralized regardless of file format integrity. Organizations should implement immediate mitigations including updating to patched versions of the Symantec Messaging Gateway, enhancing email filtering rules to block suspicious file types, and implementing additional layers of email security such as sandboxing or advanced threat protection. The ATT&CK framework categorizes this as a technique involving 'Masquerading' and 'Obfuscated Files or Information' where attackers exploit gaps in content inspection systems to deliver malicious payloads that would otherwise be blocked by standard security controls.