CVE-2006-6551 in Client Code Suite
Summary
by MITRE
PHP remote file inclusion vulnerability in libs/tucows/api/cartridges/crt_TUCOWS_domains/lib/domainutils.inc.php in Tucows Client Code Suite (CCS) 1.2.1015 and earlier allows remote attackers to execute arbitrary PHP code via a URL in the _ENV[TCA_HOME] parameter.
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Analysis
by VulDB Data Team • 12/21/2024
The vulnerability identified as CVE-2006-6551 represents a critical remote file inclusion flaw within the Tucows Client Code Suite version 1.2.1015 and earlier installations. This security weakness resides in the domainutils.inc.php file located within the Tucows CCS framework, specifically in the libs/tucows/api/cartridges/crt_TUCOWS_domains/lib directory structure. The flaw stems from insufficient input validation mechanisms that fail to properly sanitize user-supplied data before incorporating it into file inclusion operations, creating an avenue for malicious exploitation.
The technical implementation of this vulnerability occurs through the manipulation of the _ENV[TCA_HOME] parameter which serves as an environment variable containing a URL path. When the application processes this parameter without adequate validation or sanitization, it becomes susceptible to remote code execution attacks. Attackers can craft malicious URLs and inject them into the TCA_HOME environment variable, which then gets processed by the vulnerable include mechanism, effectively allowing arbitrary PHP code execution on the target system. This type of vulnerability falls under the CWE-88 category of Command Injection and aligns with the ATT&CK technique T1059.007 for Command and Scripting Interpreter.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with complete control over the affected system. Once exploited, malicious actors can upload additional malware, establish persistent backdoors, access sensitive data, and potentially use the compromised system as a launching point for further attacks within the network. The vulnerability affects the entire Tucows Client Code Suite ecosystem and could compromise multiple applications that rely on this framework. Organizations using vulnerable versions face significant risks including data breaches, system compromise, and potential regulatory violations.
Mitigation strategies for this vulnerability require immediate patching of the Tucows Client Code Suite to versions that properly validate and sanitize environment variables before processing. System administrators should implement input validation controls that filter out potentially malicious URL schemes and characters from environment variables. Network segmentation and firewall rules can help limit the attack surface by restricting access to vulnerable applications. Additionally, monitoring for unusual environment variable modifications and implementing runtime application self-protection mechanisms can provide additional defense layers. The vulnerability demonstrates the critical importance of proper input validation and the principle of least privilege in preventing remote code execution scenarios. Organizations should also consider implementing automated vulnerability scanning tools to identify similar issues in other legacy applications that may be using similar patterns for file inclusion operations.