CVE-2017-15685 in Crafter
Summary
by MITRE • 11/27/2020
Crafter CMS Crafter Studio 3.0.1 is affected by: XML External Entity (XXE). An unauthenticated attacker is able to create a site with specially crafted XML that allows the retrieval of OS files out-of-band.
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Analysis
by VulDB Data Team • 12/11/2020
CVE-2017-15685 represents a critical XML External Entity vulnerability in Crafter CMS Crafter Studio version 3.0.1 that exposes the system to unauthorized information disclosure. This vulnerability falls under the CWE-611 weakness category, which specifically addresses XML External Entity processing without proper restrictions. The flaw exists in the application's handling of XML data during site creation processes, where the system fails to adequately validate or sanitize external entity references within XML documents. An attacker can exploit this by crafting malicious XML content that references external resources, enabling the system to fetch and transmit local operating system files to an external attacker-controlled server.
The technical exploitation of this XXE vulnerability occurs during the site creation workflow where Crafter Studio processes XML configuration files without proper input sanitization. When an unauthenticated attacker submits specially crafted XML data, the CMS parser attempts to resolve external entity references, allowing for out-of-band data retrieval attacks. This vulnerability enables attackers to access sensitive files such as configuration files, database credentials, system logs, and other operating system resources that may be accessible through the application's file system. The attack vector is particularly dangerous because it does not require authentication, making it accessible to anyone who can submit content to the system.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can lead to complete system compromise when combined with other attack vectors. An attacker could extract database connection strings, application secrets, and configuration files that might reveal additional vulnerabilities within the system. The out-of-band nature of the attack allows for stealthy data exfiltration without direct interaction with the target system, making detection more difficult. This vulnerability also affects the integrity of the content management system by potentially allowing attackers to inject malicious content that could be processed by other users or automated systems within the CMS environment.
Organizations affected by this vulnerability should immediately implement mitigations including disabling external entity resolution in XML parsers, implementing strict input validation for all XML content, and applying the vendor-provided security patches. The recommended approach involves configuring the XML parser to reject external entity declarations and setting up network firewalls to prevent unauthorized outbound connections from the CMS server. Additionally, implementing web application firewalls and intrusion detection systems can help monitor for suspicious XML processing activities. According to ATT&CK framework, this vulnerability maps to T1071.004 (Application Layer Protocol: DNS) and T1041 (Exfiltration Over C2 Channel) techniques, as the attack leverages DNS resolution for data exfiltration and employs out-of-band communication patterns typical of advanced persistent threat actors. Regular security assessments and input validation testing should be conducted to prevent similar vulnerabilities in future deployments.