CVE-2007-3804 in CorePlus
Summary
by MITRE
The AntiVirus engine in the HTTP-ALG in Clavister CorePlus before 8.81.00 and 8.80.03 might allow remote attackers to bypass scanning via small files.
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Analysis
by VulDB Data Team • 07/24/2017
The vulnerability identified as CVE-2007-3804 affects the AntiVirus engine implementation within the HTTP-ALG component of Clavister CorePlus network security appliances. This issue represents a significant security weakness in the application layer gateway's antivirus functionality that could enable malicious actors to evade detection mechanisms. The flaw specifically manifests when processing small files through the HTTP application layer gateway, creating a bypass opportunity for attackers seeking to deliver malicious content without triggering the security appliance's antivirus scanning processes. The vulnerability exists in versions prior to 8.81.00 and 8.80.03 of the Clavister CorePlus platform, indicating that these releases contained a design flaw in how they handled file size thresholds for antivirus inspection.
The technical implementation flaw stems from inadequate validation of file sizes within the HTTP-ALG's antivirus engine integration. When files are processed through the application layer gateway, the system fails to properly enforce antivirus scanning for small files that fall below a certain size threshold. This creates a condition where attackers can craft malicious payloads in small file formats that bypass the security appliance's inspection capabilities entirely. The vulnerability operates at the network security appliance level where HTTP traffic is inspected and filtered, making it particularly dangerous as it allows attackers to circumvent the very security controls designed to prevent malware delivery. The flaw likely involves a conditional logic error where the antivirus engine is bypassed for files below a specific byte count, potentially as low as a few kilobytes, which is insufficient to trigger the security scanning process.
The operational impact of this vulnerability extends beyond simple malware bypass to potentially compromise entire network security postures. Organizations relying on Clavister CorePlus appliances for HTTP traffic filtering and antivirus protection face significant risk as attackers can exploit this weakness to deliver malicious payloads that would otherwise be detected and blocked. The vulnerability creates a persistent threat vector that could remain undetected for extended periods, especially in environments where network traffic monitoring is limited or where the security appliance is not properly configured to enforce comprehensive scanning. Attackers could leverage this bypass to deploy various types of malware including trojans, rootkits, and other malicious software that targets the network infrastructure. The implications are particularly severe given that HTTP traffic represents a primary vector for malware distribution, and the bypass mechanism could be easily automated to maximize attack effectiveness while remaining undetected by security monitoring systems.
Mitigation strategies for this vulnerability require immediate patching of affected Clavister CorePlus appliances to versions 8.81.00 or 8.80.03 and later. Organizations should also implement additional network monitoring to detect anomalous file transfer patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-200, which addresses "Information Exposure," as it exposes the security system to bypass mechanisms that should not exist in properly functioning security appliances. From an ATT&CK framework perspective, this vulnerability maps to T1071.004 for Application Layer Protocol: DNS and T1566 for Phishing, as attackers can use this bypass to deliver malicious content through HTTP channels. Network administrators should also consider implementing additional security controls such as deep packet inspection, file type validation, and traffic flow analysis to compensate for the bypass mechanism. Regular security assessments and vulnerability scanning should be conducted to ensure that similar weaknesses do not exist in other components of the security infrastructure, as this vulnerability demonstrates a critical flaw in how the appliance handles file size validation during security inspection processes.