CVE-2004-0053 in MAILsweeper
Summary
by MITRE
Multiple content security gateway and antivirus products allow remote attackers to bypass content restrictions via MIME messages that use fields that use RFC2047 encoding, which may be interpreted differently by mail clients.
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Analysis
by VulDB Data Team • 06/21/2018
The vulnerability described in CVE-2004-0053 represents a critical content filtering bypass issue affecting multiple security gateway and antivirus solutions. This flaw exploits the inconsistent interpretation of RFC2047 encoded MIME message fields across different mail client implementations, creating a significant gap in content security controls that malicious actors can leverage to circumvent protective measures. The vulnerability specifically targets the way security products process and evaluate email content, particularly when dealing with encoded headers and message fields that contain non-standard character encodings.
The technical root cause of this vulnerability lies in the differing approaches between content security gateways and standard mail clients when processing RFC2047 encoded content. RFC2047 defines encoding standards for non-ASCII characters in email headers, but different implementations may interpret these encodings differently during content inspection. Security products typically parse message headers to identify potential threats or content restrictions, but when RFC2047 encoding is present, the gateway may misinterpret the actual content of message fields, leading to incorrect filtering decisions. This inconsistency creates opportunities for attackers to craft malicious messages that appear benign to security scanners while containing harmful content when properly decoded by standard mail clients.
The operational impact of this vulnerability extends beyond simple bypass of content restrictions, as it fundamentally undermines the trust model between security gateways and end-user mail clients. Attackers can exploit this weakness to deliver phishing emails, malware attachments, or other malicious content that would normally be blocked by content security policies. The vulnerability affects the core functionality of security products by demonstrating that their content inspection capabilities are insufficiently robust when dealing with encoded content, potentially allowing threat actors to establish persistent access points within networks. This issue particularly impacts organizations relying on email security gateways for protection against spam, malware, and data loss prevention.
Security professionals should implement layered mitigation strategies addressing this vulnerability by ensuring that content security products properly decode and inspect all RFC2047 encoded fields before applying content restrictions. Organizations must verify that their security gateways perform consistent header decoding across all message components, rather than relying on potentially inconsistent interpretations. The mitigation approach should include regular updates to security product firmware and configuration policies that enforce strict inspection of encoded content. Additionally, network administrators should consider implementing supplementary monitoring and logging mechanisms to detect anomalous email patterns that might indicate exploitation attempts. This vulnerability aligns with CWE-119 which addresses weaknesses in the encoding and decoding of data, and maps to ATT&CK technique T1190 for exploit via content injection in email communications. Organizations should prioritize this vulnerability in their risk assessment frameworks due to its potential for bypassing critical email security controls and its relatively low complexity for exploitation.