CVE-2003-0930 in MAILsweeper
Summary
by MITRE
Clearswift MAILsweeper before 4.3.15 does not properly detect filenames in BinHex (HQX) encoded files, which allows remote attackers to bypass intended policy.
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Analysis
by VulDB Data Team • 07/03/2024
The vulnerability identified as CVE-2003-0930 affects Clearswift MAILsweeper versions prior to 4.3.15 and represents a critical flaw in content inspection and policy enforcement mechanisms. This issue specifically targets the software's ability to properly analyze and identify filenames within BinHex encoded files, which are commonly used for encoding binary data in email communications. The vulnerability arises from insufficient validation of file metadata within the encoded content, creating a potential bypass mechanism for malicious actors seeking to circumvent security policies. BinHex encoding, while less common than base64, remains a valid method for embedding binary content in email messages and is frequently encountered in enterprise email environments where such encoding may be used to transmit attachments or executable content.
The technical flaw stems from the MAILsweeper software's inadequate parsing of BinHex encoded files, particularly in how it processes the filename information embedded within the encoding structure. When processing such files, the system fails to correctly extract and validate the filename metadata that should be present in the encoded content, allowing attackers to manipulate the file identification process. This improper handling of filename detection creates a scenario where malicious files can be disguised as benign content, effectively bypassing the security controls designed to prevent unauthorized file transfers or potentially harmful attachments. The vulnerability operates at the application layer of the network stack and specifically impacts the content filtering and policy enforcement capabilities of the email security solution.
The operational impact of this vulnerability extends beyond simple policy bypass, as it represents a fundamental weakness in the email security infrastructure that could enable attackers to deliver malicious payloads undetected. Remote attackers could exploit this flaw by crafting BinHex encoded files with manipulated filename information that would not be properly recognized by the MAILsweeper system, potentially allowing malware distribution, data exfiltration attempts, or other malicious activities to proceed without detection. The vulnerability particularly affects organizations that rely on MAILsweeper for email content filtering and that may be processing email traffic containing BinHex encoded attachments as part of their normal operations. This weakness could be leveraged in targeted attacks against organizations with specific email security policies that depend on accurate file identification for enforcement purposes.
Organizations should implement immediate mitigations including updating to MAILsweeper version 4.3.15 or later, which contains the necessary fixes for proper BinHex filename detection. Additionally, security teams should review their existing email security policies to ensure that multiple layers of protection are in place, as reliance on a single content inspection mechanism creates potential attack vectors. The vulnerability aligns with CWE-20, which addresses improper input validation, and represents a classic case of insufficient data validation in security applications. From an ATT&CK framework perspective, this vulnerability maps to techniques involving evasion and privilege escalation through content manipulation, specifically targeting the defense evasion tactic where adversaries attempt to bypass security controls by manipulating file characteristics or metadata. Security professionals should also consider implementing additional monitoring and logging of email content processing activities to detect potential exploitation attempts and ensure comprehensive protection against similar vulnerabilities in other security applications.