CVE-2016-8005 in McAfee Email Gateway
Summary
by MITRE
File extension filtering vulnerability in Intel Security McAfee Email Gateway (MEG) before 7.6.404h1128596 allows attackers to fail to identify the file name properly via scanning an email with a forged attached filename that uses a null byte within the filename extension.
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Analysis
by VulDB Data Team • 08/19/2020
The CVE-2016-8005 vulnerability represents a critical file extension filtering flaw within Intel Security McAfee Email Gateway software that fundamentally undermines the email security mechanisms designed to protect organizations from malicious attachments. This vulnerability specifically affects MEG versions prior to 7.6.404h1128596 and exploits a fundamental weakness in how the system processes and validates file extensions during email scanning operations. The flaw enables attackers to bypass content filtering controls by crafting malicious email attachments with forged filenames that contain null bytes within the file extension portion, thereby circumventing the gateway's ability to properly identify and block potentially harmful file types.
The technical nature of this vulnerability stems from improper input validation and string parsing within the MEG email scanning engine. When an email attachment is processed, the system performs file extension checks to determine whether the attachment should be blocked based on predefined security policies. However, the presence of null bytes within the filename extension creates a parsing anomaly that causes the gateway to misinterpret the file type, effectively allowing malicious files to slip through security controls undetected. This occurs because the null byte character terminates string processing in many programming environments, causing the system to only evaluate the portion of the filename preceding the null byte rather than the complete filename. The vulnerability operates at the application level and demonstrates a classic weakness in input sanitization that aligns with CWE-120, which addresses buffer overflow conditions and their potential for exploitation.
The operational impact of this vulnerability extends beyond simple bypass of security controls, creating significant risk for organizations relying on MEG for email security. Attackers can exploit this weakness to deliver malware, phishing payloads, or other malicious content through email channels that would normally be blocked by standard security policies. The vulnerability is particularly dangerous because it requires no sophisticated techniques to exploit, merely the insertion of a null byte character within the filename extension, making it accessible to threat actors with minimal technical expertise. Organizations may experience data breaches, system compromise, or other security incidents as a result of this vulnerability, as the compromised email gateway fails to provide the expected protection against known malicious file types.
Mitigation strategies for CVE-2016-8005 should prioritize immediate software updates to the latest available version of McAfee Email Gateway that contains the necessary patches to address the null byte handling issue. Organizations should also implement additional layers of email security filtering beyond the default MEG controls, including enhanced sandboxing capabilities, advanced threat detection systems, and multi-stage content inspection processes. Network administrators should conduct thorough vulnerability assessments to identify any potential exploitation attempts and establish monitoring protocols to detect anomalous email traffic patterns that might indicate attempted exploitation of this vulnerability. The remediation process should also include comprehensive security awareness training for personnel to recognize and report suspicious email activity, as well as regular security policy reviews to ensure adequate protection against similar classes of vulnerabilities. This vulnerability demonstrates the critical importance of proper input validation and string handling in security software, aligning with ATT&CK technique T1190 for exploitation of remote services and T1078 for valid accounts usage, as the bypassed controls could enable further malicious activity within compromised networks.