CVE-2016-6852 in OX AppSuite
Summary
by MITRE
An issue was discovered in Open-Xchange OX App Suite before 7.8.2-rev8. Users can provide local file paths to the RSS reader; the response and error code give hints about whether the provided file exists or not. Attackers may discover specific system files or library versions on the middleware server to prepare further attacks.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 07/08/2019
The vulnerability identified as CVE-2016-6852 affects Open-Xchange OX App Suite versions prior to 7.8.2-rev8, representing a classic information disclosure weakness that stems from improper input validation within the RSS reader functionality. This flaw allows authenticated users to exploit a path traversal mechanism by providing local file paths directly to the RSS reader component, creating a scenario where the application's response behavior inadvertently reveals system-level information about file existence and potentially system configuration details. The vulnerability operates at the application layer and demonstrates a fundamental lack of proper sanitization and validation of user-supplied input, creating an information leakage channel that can be systematically exploited by malicious actors.
The technical implementation of this vulnerability resides in the RSS reader's handling of file path parameters, where the application fails to properly validate or sanitize input before processing. When a user provides a local file path to the RSS reader, the system's response includes error codes and messages that distinguish between different types of file access failures. This differential response behavior creates a timing channel or error-based information disclosure mechanism that allows attackers to determine whether specific files exist on the server filesystem. The vulnerability specifically manifests when the application attempts to process the provided file path and returns different error codes or response structures depending on whether the file exists, is readable, or encounters access restrictions. This behavior directly maps to CWE-200, which defines information exposure vulnerabilities where systems inadvertently reveal sensitive information about their internal state or configuration through error messages, response codes, or other indirect indicators.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with critical reconnaissance data that can be leveraged for more sophisticated attacks. By systematically testing various file paths, attackers can map out the server's filesystem structure, identify installed software versions, and potentially discover sensitive configuration files or library locations. This information can be used to tailor subsequent attacks, such as exploiting known vulnerabilities in specific software versions, conducting targeted attacks against identified system components, or planning more advanced exploitation techniques. The vulnerability essentially provides an attacker with a reconnaissance tool that operates without requiring special privileges beyond authentication access to the RSS reader functionality. According to ATT&CK framework category T1213, this represents a data from information repositories technique where adversaries collect information about the target system to inform their subsequent operations, making this vulnerability particularly dangerous as it enables a reconnaissance phase that can significantly reduce the effort required for more advanced exploitation.
The mitigation strategy for CVE-2016-6852 requires immediate implementation of proper input validation and sanitization within the RSS reader component, ensuring that all user-supplied file paths are properly validated and that error responses do not reveal system-level information about file existence. Organizations should upgrade to Open-Xchange OX App Suite version 7.8.2-rev8 or later, which includes patches specifically addressing this vulnerability. Additionally, implementing proper access controls and input filtering mechanisms that prevent direct file path manipulation within the RSS reader functionality will eliminate the attack vector. Security teams should also consider implementing monitoring for unusual patterns in RSS reader usage that might indicate reconnaissance activity and establish proper error handling procedures that provide generic responses regardless of file access outcomes. The vulnerability demonstrates the importance of secure coding practices and input validation, particularly in components that handle user-supplied data that could be used to access system resources, aligning with security best practices outlined in OWASP Top 10 and NIST cybersecurity frameworks that emphasize the need for robust input validation and proper error handling to prevent information disclosure vulnerabilities.