CVE-2016-9853 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 fopen wrapper issue.
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Analysis
by VulDB Data Team • 06/23/2019
The vulnerability identified as CVE-2016-9853 represents a critical information disclosure flaw within phpMyAdmin, a widely used web-based database management tool. This security issue stems from improper error handling mechanisms that occur when specific scripts within phpMyAdmin are invoked through unexpected execution paths. The flaw manifests when phpMyAdmin encounters certain error conditions, particularly during export operations, causing the application to reveal sensitive system information through error messages. The vulnerability specifically affects versions 4.4.x prior to 4.4.15.9 and 4.6.x prior to 4.6.5, indicating a prolonged period of exposure across multiple stable release lines. This type of information disclosure vulnerability falls under the CWE-209 classification, which addresses "Information Exposure Through an Error Message," and aligns with ATT&CK technique T1212 for "Exploitation for Credential Access" as the leaked path information can aid attackers in understanding the target system's file structure and potentially facilitate further exploitation attempts.
The technical implementation of this vulnerability involves the interaction between phpMyAdmin's export functionality and the PHP runtime environment's handling of file operations. When an execution timeout occurs during export processing, the system attempts to write error information to the export file, inadvertently including the complete server path where phpMyAdmin is installed. This occurs through the fopen wrapper mechanism, which provides a generic interface for accessing files and streams in PHP applications. The vulnerability exploits the fact that error messages are not properly sanitized before being included in output files, allowing attackers to gain knowledge about the underlying file system structure. The exposure of absolute paths creates a significant risk because it provides attackers with precise information about the server environment, including directory hierarchy and installation locations that could be leveraged for subsequent attacks.
The operational impact of CVE-2016-9853 extends beyond simple information disclosure, as the leaked path information can significantly aid malicious actors in planning more sophisticated attacks against the affected systems. The exposure of the full directory path creates a foundation for attackers to understand the server's configuration and potentially identify other vulnerabilities or misconfigurations that might exist within the same environment. This information disclosure vulnerability particularly affects database administrators who rely on phpMyAdmin for their work, as it provides attackers with insights into the deployment architecture of database management systems. The vulnerability's persistence across multiple minor versions indicates that it was not properly addressed in the codebase, creating a prolonged window of exposure for organizations using affected versions. Organizations that fail to upgrade to patched versions remain at risk of having their system paths exposed, which could lead to privilege escalation attempts or targeted attacks against the database infrastructure.
Organizations affected by this vulnerability should immediately implement mitigations to protect their systems from potential exploitation. The primary and most effective mitigation strategy involves upgrading to phpMyAdmin versions 4.4.15.9 or 4.6.5, which contain the necessary code fixes to prevent the information disclosure. Additionally, administrators should implement proper input validation and error handling mechanisms to prevent similar vulnerabilities from occurring in custom applications. The remediation process should include comprehensive testing of the upgraded environment to ensure that all export functionality operates correctly without exposing system paths. Security monitoring should be enhanced to detect any attempts to access phpMyAdmin through unusual execution paths that might trigger the vulnerability. Organizations should also consider implementing web application firewalls or security headers that can help mask or prevent the exposure of system information in error responses. Regular vulnerability assessments and security audits should be conducted to identify and address similar information disclosure vulnerabilities in other applications within the infrastructure, as this type of flaw represents a common vector for initial compromise in many attack scenarios.