CVE-2016-9852 in phpMyAdmin
Summary
by MITRE
An issue was discovered in phpMyAdmin. By calling some scripts that are part of phpMyAdmin in an unexpected way, it is possible to trigger phpMyAdmin to display a PHP error message which contains the full path of the directory where phpMyAdmin is installed. During an execution timeout in the export functionality, the errors containing the full path of the directory of phpMyAdmin are written to the export file. All 4.6.x versions (prior to 4.6.5), and 4.4.x versions (prior to 4.4.15.9) are affected. This CVE is for the curl wrapper issue.
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Analysis
by VulDB Data Team • 06/23/2019
The vulnerability identified as CVE-2016-9852 represents a critical information disclosure flaw within phpMyAdmin that exposes the full server path through error messages generated during specific operational conditions. This issue stems from improper error handling mechanisms within the application's export functionality, specifically when dealing with execution timeouts that occur during data export operations. The vulnerability affects versions 4.4.x prior to 4.4.15.9 and 4.6.x prior to 4.6.5, making it a widespread concern across multiple release branches of the popular database management tool.
The technical flaw manifests when phpMyAdmin's export scripts encounter execution timeouts, particularly in scenarios involving the curl wrapper functionality. During these timeout conditions, the application generates PHP error messages that inadvertently include the complete file system path where phpMyAdmin is installed. These error messages are then written directly to the export file, creating a situation where sensitive system information becomes accessible to unauthorized users who can trigger the vulnerable code path. The vulnerability is classified under CWE-200, which deals with information exposure through error messages, and represents a classic case of improper error handling that reveals system internals.
The operational impact of this vulnerability extends beyond simple information disclosure, as the exposed full paths can provide attackers with crucial reconnaissance information for subsequent exploitation attempts. When an attacker can obtain the complete installation path, they gain valuable insights into the server's file structure, which can be leveraged to craft more sophisticated attacks targeting specific file locations, directory permissions, or potential privilege escalation vectors. The vulnerability particularly affects environments where phpMyAdmin is used for database administration tasks, as the exported files containing the path information could be accessed by unauthorized users or inadvertently exposed through various attack vectors. This information disclosure can be exploited in conjunction with other vulnerabilities to facilitate more comprehensive attacks against the affected systems.
Mitigation strategies for CVE-2016-9852 primarily focus on upgrading to patched versions of phpMyAdmin, specifically version 4.4.15.9 or 4.6.5, which address the improper error handling in the export functionality. Organizations should also implement proper error handling configurations that prevent sensitive path information from being exposed to end users, including the implementation of custom error pages and the disabling of detailed error messages in production environments. Security measures should include monitoring for unusual export activity patterns and implementing access controls that limit who can trigger export operations, particularly those involving curl wrapper functionality. The vulnerability aligns with ATT&CK technique T1083, which covers directory and file discovery, as the exposed paths provide attackers with systematic access to file system structures that would otherwise remain hidden from casual observation. Additionally, this vulnerability demonstrates the importance of proper input validation and error handling in web applications, as the issue could be prevented through robust sanitization of error messages and the implementation of secure coding practices that prevent information leakage during exceptional conditions.