CVE-2016-9857 in phpMyAdmin
Summary
by MITRE
An issue was discovered in phpMyAdmin. XSS is possible because of a weakness in a regular expression used in some JavaScript processing. All 4.6.x versions (prior to 4.6.5), 4.4.x versions (prior to 4.4.15.9), and 4.0.x versions (prior to 4.0.10.18) are affected.
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Analysis
by VulDB Data Team • 06/23/2019
The vulnerability CVE-2016-9857 represents a cross-site scripting weakness in phpMyAdmin that stems from a flawed regular expression implementation in JavaScript processing components. This issue affects multiple version lines including 4.6.x prior to 4.6.5, 4.4.x prior to 4.4.15.9, and 4.0.x prior to 4.0.10.18, indicating a widespread impact across the software's release history. The vulnerability resides in the client-side JavaScript code that processes user input, creating an attack surface where malicious scripts can be injected and executed within the context of a victim's browser session.
The technical flaw manifests through improper input validation within the regular expression pattern used to sanitize or process user-provided data in JavaScript contexts. When phpMyAdmin handles certain user inputs through its JavaScript components, the flawed regex pattern fails to properly escape or sanitize special characters that could be interpreted as executable script code. This weakness allows attackers to inject malicious JavaScript payloads that bypass the application's security controls, particularly when user input is reflected back in the browser without proper sanitization. The vulnerability specifically impacts the JavaScript processing layer rather than server-side operations, making it particularly dangerous as it operates within the user's browser environment where it can access session cookies and perform actions on behalf of authenticated users.
The operational impact of this vulnerability extends beyond simple script injection, as it enables attackers to perform a range of malicious activities including session hijacking, credential theft, and data exfiltration. An attacker could craft malicious input that, when processed by the vulnerable phpMyAdmin interface, would execute arbitrary JavaScript code in the victim's browser. This could lead to unauthorized access to database operations, modification of database content, or even complete compromise of the database administration interface. The vulnerability is particularly concerning in environments where phpMyAdmin is publicly accessible or where users have elevated privileges, as successful exploitation could result in full database compromise and potential lateral movement within the network infrastructure. The widespread affected versions suggest that many installations would have been vulnerable for extended periods, increasing the potential attack surface and impact.
Mitigation strategies for CVE-2016-9857 primarily involve immediate software updates to patched versions, with phpMyAdmin releases 4.6.5, 4.4.15.9, and 4.0.10.18 addressing the vulnerable regular expression implementation. Organizations should conduct comprehensive vulnerability assessments to identify all affected installations and prioritize patching efforts, particularly in environments where phpMyAdmin is exposed to untrusted users or networks. Additional defensive measures include implementing web application firewalls to monitor and filter suspicious input patterns, enforcing strict content security policies to limit script execution, and conducting regular security audits of JavaScript components. From a cybersecurity framework perspective, this vulnerability aligns with CWE-79 Cross-site Scripting and maps to ATT&CK techniques involving client-side exploitation and credential access. Network segmentation and access controls should be implemented to limit exposure, while user education regarding suspicious input handling can help prevent social engineering attacks that might exploit this vulnerability. The remediation process should also include monitoring for potential exploitation attempts through log analysis and implementing proper input validation at multiple layers of the application architecture.