CVE-2017-6344 in Grails PDF Plugin
Summary
by MITRE
XML External Entity (XXE) vulnerability in Grails PDF Plugin 0.6 allows remote attackers to read arbitrary files via a crafted XML document.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/02/2020
The CVE-2017-6344 vulnerability represents a critical XML External Entity processing flaw in the Grails PDF Plugin version 0.6, which exposes applications to remote file inclusion attacks. This vulnerability falls under the Common Weakness Enumeration category CWE-611, specifically targeting improper restriction of XML external entity references. The flaw occurs when the plugin processes XML documents without adequate sanitization of external entity declarations, allowing malicious actors to manipulate the XML parser behavior through crafted input.
The technical implementation of this vulnerability exploits the way XML parsers handle external entity references during document processing. When the Grails PDF Plugin encounters an XML document containing external entity declarations, it fails to properly validate or restrict these references, enabling attackers to specify arbitrary file paths that the parser will attempt to resolve and include in the processing context. This creates a pathway for remote attackers to access sensitive files on the server filesystem, potentially including configuration files, database credentials, or application source code, depending on the server's file permissions and the application's security posture.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable attackers to perform further exploitation activities within the compromised environment. Attackers can leverage this XXE vulnerability to conduct server-side request forgery attacks, potentially accessing internal network resources that would otherwise be isolated from direct external access. The vulnerability affects systems where the Grails PDF Plugin is installed and actively processing XML input, making it particularly dangerous in enterprise environments where PDF generation is commonly used for reports, invoices, or other business-critical documents. The attack vector requires only that an attacker can submit a crafted XML document to a vulnerable application, making it accessible to threat actors with minimal prerequisites.
Mitigation strategies for CVE-2017-6344 should prioritize immediate patching of the Grails PDF Plugin to version 0.7 or later, which contains the necessary fixes for proper XML entity validation. Organizations should implement comprehensive input validation and sanitization measures for all XML processing components, ensuring that external entity declarations are either completely disabled or properly restricted through secure parser configurations. Security controls should include disabling external entity resolution in XML parsers and implementing strict access controls on file system resources that might be targeted through such attacks. The vulnerability demonstrates the importance of following secure coding practices and adhering to the principle of least privilege in XML processing, as outlined in various security frameworks and standards that emphasize proper input validation and secure configuration of XML parsers to prevent similar XXE vulnerabilities across different application components and frameworks.