CVE-2000-0067 in Merchant Connection Kit
Summary
by MITRE
CyberCash Merchant Connection Kit (MCK) allows local users to modify files via a symlink attack.
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Analysis
by VulDB Data Team • 04/20/2026
The vulnerability identified as CVE-2000-0067 resides within the CyberCash Merchant Connection Kit version 1.0, a payment processing component widely deployed in e-commerce environments during the late 1990s. This flaw represents a classic symlink attack vulnerability that exploited improper file handling mechanisms within the software's installation and configuration processes. The vulnerability specifically affects systems where the MCK component is installed with insufficient security controls, creating an avenue for local attackers to manipulate critical system files through symbolic link manipulation techniques.
The technical implementation of this vulnerability stems from the MCK's failure to properly validate file paths during its operation, particularly when processing configuration files or temporary data structures. Attackers could create malicious symbolic links in strategic locations within the filesystem, which the MCK would then follow and modify without proper authorization checks. This behavior aligns with CWE-59, which describes improper handling of symbolic links, and demonstrates how insufficient input validation can lead to privilege escalation and unauthorized file modification. The flaw operates at the operating system level where the software executes with elevated privileges, making the impact significantly more severe than typical local file access vulnerabilities.
The operational impact of CVE-2000-0067 extends beyond simple file modification capabilities, as it provides attackers with the potential to compromise entire payment processing systems. Local users with minimal privileges could exploit this vulnerability to modify critical configuration files that control payment gateway communications, potentially leading to unauthorized transaction processing or complete system compromise. The attack vector is particularly concerning because it requires minimal technical expertise to execute successfully, making it attractive to malicious actors who might otherwise lack advanced penetration testing skills. This vulnerability effectively undermines the security model of the payment processing infrastructure, as it allows attackers to subvert the intended access controls and potentially access sensitive payment data.
Mitigation strategies for this vulnerability should focus on immediate patching of affected systems and implementation of proper file system permissions. Organizations should ensure that the MCK component is installed with restrictive file permissions and that symbolic link resolution is disabled or properly validated during file operations. The remediation process should include comprehensive system auditing to identify any potential compromise from prior exploitation attempts. Security controls should also implement proper file integrity monitoring to detect unauthorized modifications to critical system files. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and persistence, requiring organizations to implement robust access control mechanisms and regular security assessments to prevent exploitation. The vulnerability demonstrates the critical importance of proper file system handling in security-sensitive applications and highlights the need for comprehensive security testing during software development lifecycle phases.