CVE-2003-0564 in Groupmax Mail Security Option
Summary
by MITRE
Multiple vulnerabilities in multiple vendor implementations of the Secure/Multipurpose Internet Mail Extensions (S/MIME) protocol allow remote attackers to cause a denial of service and possibly execute arbitrary code via an S/MIME email message containing certain unexpected ASN.1 constructs, as demonstrated using the NISSC test suite.
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Analysis
by VulDB Data Team • 12/15/2024
The vulnerability described in CVE-2003-0564 represents a critical security flaw affecting multiple implementations of the Secure/Multipurpose Internet Mail Extensions protocol, commonly known as S/MIME. This protocol serves as a standard for encrypting and signing email messages to ensure confidentiality and integrity in email communications. The vulnerability stems from insufficient validation of ASN.1 (Abstract Syntax Notation One) structures within S/MIME email messages, which are fundamental to the protocol's cryptographic operations and message formatting. ASN.1 is a standard interface description language used extensively in telecommunications and security protocols, including X.509 certificates and PKI implementations that S/MIME relies upon for its security foundation.
The technical flaw manifests when S/MIME implementations fail to properly parse and validate ASN.1 constructs contained within email messages. Attackers can craft specially malformed S/MIME emails with unexpected or malformed ASN.1 sequences that cause the receiving mail server or client software to crash or behave unpredictably. This vulnerability operates at the protocol parsing layer where ASN.1 decoders encounter constructs that exceed expected boundaries or violate standard ASN.1 encoding rules. The issue is particularly dangerous because it can be exploited through email delivery mechanisms, allowing remote attackers to trigger these malformed constructs without requiring any special privileges or authentication. The vulnerability is classified as a buffer overflow or parsing error in ASN.1 decoders, which falls under CWE-121 for buffer overflow conditions and CWE-122 for buffer overflow conditions. The NISSC test suite demonstrates how specific ASN.1 constructs can be crafted to exploit these parsing deficiencies, making the vulnerability applicable across various implementations from different vendors.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enabling remote code execution on affected systems. When an S/MIME email containing malicious ASN.1 constructs is processed by vulnerable software, the parsing failure can result in memory corruption that attackers might exploit to execute arbitrary code with the privileges of the affected service. This creates a significant threat to email infrastructure, as compromised mail servers could become attack vectors for broader network infiltration. The vulnerability affects email clients, servers, and gateway systems that process S/MIME messages, making it particularly dangerous in enterprise environments where email is a critical communication channel. Organizations running vulnerable implementations face potential data breaches, service disruption, and compromise of email-based authentication systems that rely on S/MIME for secure communication.
Mitigation strategies for CVE-2003-0564 require immediate patching of affected S/MIME implementations, with vendors releasing updates that strengthen ASN.1 parsing validation and implement proper bounds checking. System administrators should deploy filters to detect and block malformed S/MIME messages, particularly those containing unusual ASN.1 structures that are not commonly found in legitimate email traffic. Network segmentation and email gateway filtering can help contain the impact of exploitation attempts while patches are deployed. The vulnerability demonstrates the importance of robust input validation and defensive programming practices, aligning with ATT&CK technique T1203 for exploitation for privilege escalation and T1078 for valid accounts. Organizations should also implement monitoring for unusual email processing errors and system crashes that might indicate exploitation attempts, as the vulnerability can be used for both denial of service and more sophisticated attacks. Regular security assessments of email infrastructure and compliance with security standards such as those defined in the ISO/IEC 15408 Common Criteria or NIST SP 800-53 should be enforced to prevent similar vulnerabilities in future implementations.