CVE-2016-9855 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 PMA_shutdownDuringExport issue.
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Analysis
by VulDB Data Team • 06/23/2019
The vulnerability identified as CVE-2016-9855 represents a critical information disclosure flaw within phpMyAdmin that stems from improper error handling during specific export operations. This weakness allows attackers to obtain sensitive system information through crafted requests that trigger PHP error messages containing the complete file system path where phpMyAdmin is installed. The vulnerability specifically manifests when phpMyAdmin's export functionality encounters execution timeouts, causing error messages with path information to be written directly into the export files generated by the application. This issue affects phpMyAdmin versions 4.4.x prior to 4.4.15.9 and 4.6.x prior to 4.6.5, creating a window of exposure for installations running these vulnerable versions.
The technical implementation of this vulnerability involves the interaction between phpMyAdmin's export module and PHP's error reporting mechanisms during timeout scenarios. When the export process exceeds predefined time limits, the system generates PHP error messages that contain the absolute path to the phpMyAdmin installation directory. These error messages are subsequently embedded within the export files, making them accessible to anyone who can access these files. The flaw demonstrates poor input validation and error handling practices, as the application fails to sanitize or suppress sensitive path information that should not be exposed to end users or external parties. This vulnerability falls under CWE-209, which specifically addresses "Information Exposure Through an Error Message," and represents a classic example of how error handling can inadvertently leak system information to unauthorized parties.
The operational impact of CVE-2016-9855 extends beyond simple information disclosure, as the leaked directory paths can provide attackers with crucial reconnaissance data for subsequent exploitation attempts. Knowledge of the full system path enables attackers to better understand the server environment, potentially aiding in the development of more targeted attacks against the system. The vulnerability can be exploited through direct manipulation of phpMyAdmin's export functionality, making it particularly dangerous for web applications that rely on this tool for database management. Attackers can craft specific requests that trigger the timeout condition, thereby forcing phpMyAdmin to write the sensitive path information into export files. This information disclosure can facilitate further attacks by providing insights into the server's file structure and potentially revealing other system components that might be vulnerable to exploitation. The vulnerability also aligns with ATT&CK technique T1083, which covers "File and Directory Discovery," as the leaked paths essentially provide attackers with detailed information about the application's installation structure.
Organizations affected by this vulnerability should prioritize immediate remediation through version upgrades to phpMyAdmin 4.4.15.9 or 4.6.5, which contain the necessary patches to address the improper error handling. Additionally, administrators should implement proper input validation and error suppression mechanisms within their phpMyAdmin installations to prevent the exposure of system information. The fix typically involves modifying the export functionality to suppress or sanitize error messages before they are written to export files, ensuring that no sensitive path information is included in the output. Security monitoring should include checks for unexpected error messages in export files, and system administrators should review their phpMyAdmin configurations to ensure that error reporting is appropriately restricted in production environments. Regular security assessments and vulnerability scanning should be conducted to identify any other potential information disclosure vulnerabilities that could provide similar attack vectors.