CVE-2017-14979 in Gxlcms
Summary
by MITRE
Gxlcms uses an unsafe character-replacement approach in an attempt to restrict access, which allows remote attackers to read arbitrary files via modified pathnames in the s parameter to index.php, related to Lib/Admin/Action/TplAction.class.php and Lib/Admin/Common/function.php.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 11/21/2019
The vulnerability identified as CVE-2017-14979 affects Gxlcms, a content management system that employs an insecure character replacement mechanism to restrict file access. This flaw resides in the Lib/Admin/Action/TplAction.class.php and Lib/Admin/Common/function.php components of the application, creating a path traversal vulnerability that can be exploited by remote attackers. The system's attempt to sanitize user input through character replacement proves insufficient, allowing malicious actors to manipulate the s parameter in index.php to access unauthorized files. This represents a classic example of inadequate input validation where the security mechanism itself introduces the vulnerability rather than mitigating it.
The technical implementation of this vulnerability stems from the application's flawed approach to path sanitization, which falls under CWE-22 - Improper Limitation of a Pathname to a Restricted Directory. The unsafe character replacement technique used by Gxlcms fails to properly validate or sanitize the pathname parameter, allowing attackers to craft malicious input that bypasses intended access controls. When the s parameter is modified to include directory traversal sequences such as ../ or ..\, the system processes these inputs without adequate verification, resulting in arbitrary file read access. This weakness directly enables attackers to navigate the file system beyond the intended boundaries and retrieve sensitive files that should remain protected.
From an operational perspective, this vulnerability poses significant risks to the confidentiality and integrity of the affected system. Remote attackers can leverage this weakness to access configuration files, database credentials, application source code, and potentially sensitive user data stored on the server. The impact extends beyond simple information disclosure as the ability to read arbitrary files can lead to further exploitation opportunities, including the potential to execute code or escalate privileges. The vulnerability's remote exploitability means that attackers do not require physical access to the system or local network presence to carry out attacks, making it particularly dangerous in publicly accessible environments. Security professionals should note that this vulnerability aligns with attack patterns described in the MITRE ATT&CK framework under techniques related to credential access and privilege escalation through path traversal methods.
The remediation strategy for CVE-2017-14979 requires implementing proper input validation and sanitization mechanisms that do not rely on character replacement approaches. Organizations should adopt whitelist-based validation techniques that explicitly define acceptable input patterns rather than attempting to remove or replace potentially dangerous characters. The system must implement proper path validation that ensures all file access operations occur within designated directories and that user-supplied input cannot manipulate the intended file paths. Additionally, implementing proper access controls and privilege separation can mitigate the impact of such vulnerabilities. Security measures should include regular input validation testing, proper file system permissions, and comprehensive logging of file access attempts to detect potential exploitation attempts. The fix should also incorporate principle of least privilege concepts where the application runs with minimal required permissions to prevent further escalation if exploitation occurs. Organizations should conduct thorough security testing including penetration testing and code review to ensure that similar vulnerabilities do not exist in other parts of the application or related systems.