CVE-2016-5000 in Retail Order Broker
Summary
by MITRE
The XLSX2CSV example in Apache POI before 3.14 allows remote attackers to read arbitrary files via a crafted OpenXML document containing an external entity declaration in conjunction with an entity reference, related to an XML External Entity (XXE) issue.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 11/02/2022
The vulnerability identified as CVE-2016-5000 represents a critical XML External Entity (XXE) flaw within Apache POI's XLSX2CSV example utility. This vulnerability affects versions of Apache POI prior to 3.14 and exposes systems to remote code execution risks through maliciously crafted OpenXML documents. The flaw specifically manifests when the utility processes spreadsheet files containing external entity declarations combined with entity references, creating a pathway for unauthorized file access. This issue falls under the CWE-611 category of Improper Restriction of XML External Entity Reference, which is a well-documented weakness in XML processing systems that allows attackers to exploit the parsing behavior of XML parsers. The vulnerability operates at the application layer and can be classified under the ATT&CK technique T1059.001 for Command and Scripting Interpreter, as it enables attackers to potentially execute arbitrary commands through file access mechanisms.
The technical exploitation of this vulnerability requires an attacker to craft a malicious OpenXML document that includes XML external entity declarations within the spreadsheet structure. When Apache POI's XLSX2CSV example processes this crafted document, it fails to properly validate or sanitize external entity references, allowing the parser to resolve and access external resources. This can result in attackers reading arbitrary files from the server filesystem, potentially including sensitive configuration files, database credentials, or other confidential data. The vulnerability is particularly dangerous because it leverages the standard XML parsing capabilities that Apache POI uses internally, making it difficult to detect through conventional security measures. The XXE attack vector is amplified by the fact that the vulnerability exists in a utility designed for document conversion, making it more likely to be used in real-world scenarios where users might process untrusted spreadsheet files from unknown sources.
The operational impact of CVE-2016-5000 extends beyond simple information disclosure, as it creates a potential gateway for more sophisticated attacks within network environments. Organizations that process untrusted spreadsheet files, particularly in environments where Apache POI is used for document conversion, face significant risk of unauthorized data access and potential system compromise. The vulnerability can be exploited in various attack scenarios including server-side request forgery attacks, where attackers might attempt to access internal network resources that would normally be protected by firewalls or network segmentation. The risk is particularly elevated in web applications that utilize Apache POI for processing user-uploaded files, as these applications become vulnerable to attacks that could lead to complete system compromise. This vulnerability also demonstrates the importance of proper input validation and secure XML parsing practices, as the issue stems from insufficient restrictions on external entity resolution within the XML parser configuration.
The recommended mitigations for CVE-2016-5000 primarily focus on upgrading to Apache POI version 3.14 or later, which includes proper protections against XXE attacks. Organizations should also implement strict input validation for all spreadsheet files processed through Apache POI, particularly when handling untrusted content from external sources. Security configurations should disable external entity resolution in XML parsers and implement proper sandboxing mechanisms for document processing. Additional protective measures include network segmentation to limit access to sensitive resources, implementing web application firewalls to detect and block malicious XML content, and conducting regular security assessments to identify potential XXE vulnerabilities in other applications. The remediation process should also involve comprehensive staff training on secure coding practices and the importance of validating all external inputs, as this vulnerability highlights the critical need for robust security controls in XML processing applications. Organizations should also consider implementing automated scanning tools that can detect XXE vulnerabilities in their applications and maintain updated threat intelligence to stay informed about similar vulnerabilities in related software components.