CVE-2003-1015 in MAILsweeper
Summary
by MITRE
Multiple content security gateway and antivirus products allow remote attackers to bypass content restrictions via MIME messages that use whitespace in an unusual fashion, which may be interpreted differently by mail clients.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 06/21/2018
The vulnerability described in CVE-2003-1015 represents a significant content filtering bypass issue affecting multiple security gateway and antivirus products from various vendors. This weakness stems from improper handling of whitespace characters within MIME message structures, creating a parsing inconsistency that attackers can exploit to circumvent content restrictions. The flaw specifically manifests when mail clients interpret whitespace characters in unexpected ways during message parsing, allowing malicious content to slip through security controls that should have blocked it based on content type or file extension restrictions.
This vulnerability operates at the application layer of network security systems, targeting the core functionality of content security gateways that inspect and filter email traffic. The technical root cause involves the inconsistent interpretation of whitespace characters within MIME headers and message bodies, where different mail client implementations may process these characters differently than the security gateway's content filtering engine. This discrepancy creates a parsing gap that attackers can manipulate by crafting specially formatted MIME messages containing unusual whitespace sequences that bypass the security controls while appearing legitimate to the receiving mail client.
The operational impact of this vulnerability extends beyond simple content bypass, as it undermines the fundamental security posture of organizations relying on these content security products. Attackers can leverage this weakness to deliver malicious content including executable files, scripts, or other potentially harmful attachments that would normally be blocked by content filters. The vulnerability affects the integrity of email security policies and can result in unauthorized access to sensitive information, malware delivery, or other security breaches that compromise the organization's defensive infrastructure. Security administrators may experience false negatives in their content filtering systems, leading to potential security incidents that could have been prevented.
Organizations should implement comprehensive mitigation strategies that include updating security gateway firmware and software to versions that address the whitespace handling inconsistencies, configuring additional content filtering rules that specifically target unusual whitespace patterns, and implementing multiple layers of email security validation. The vulnerability aligns with CWE-129 and CWE-772 categories related to improper input validation and insufficient input sanitization, while also mapping to ATT&CK technique T1192 for Spearphishing Attachments and T1071.3 for Application Layer Protocol: Email Protocols, highlighting the need for robust input validation and content inspection mechanisms. Security teams should also consider implementing network segmentation and additional email authentication measures such as DMARC, SPF, and DKIM to reduce the potential impact of successful exploitation attempts.