CVE-2016-10400 in ATutor
Summary
by MITRE
Directory Traversal exists in ATutor before 2.2.2 via the icon parameter to /mods/_core/courses/users/create_course.php. The attacker can read an arbitrary file by visiting get_course_icon.php?id= after the traversal attack.
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Analysis
by VulDB Data Team • 12/13/2022
The vulnerability identified as CVE-2016-10400 represents a critical directory traversal flaw within ATutor version 2.2.1 and earlier, classified under CWE-22 - Improper Limitation of a Pathname to a Restricted Directory. This weakness allows attackers to manipulate file access by exploiting improper input validation in the course creation module. The specific attack vector occurs through the icon parameter in the /mods/_core/courses/users/create_course.php script, where user-supplied input is directly incorporated into file system operations without adequate sanitization or validation. The vulnerability stems from the application's failure to properly restrict file path access, enabling attackers to navigate beyond the intended directory boundaries and access arbitrary files on the server.
The technical implementation of this vulnerability allows an attacker to construct malicious file paths that bypass normal access controls. When the application processes the icon parameter, it directly uses the provided value in file system operations without proper canonicalization or path validation. This creates a scenario where an attacker can append directory traversal sequences such as ../ to navigate up the file system hierarchy. The impact is further amplified by the fact that the vulnerability can be exploited through the get_course_icon.php?id= endpoint, which serves as an intermediary that processes the malicious path and returns the contents of arbitrary files. This type of vulnerability falls under ATT&CK technique T1083 - File and Directory Discovery, as it enables attackers to enumerate and access sensitive files that should remain protected.
The operational impact of this vulnerability is severe, as it provides attackers with unauthorized access to potentially sensitive data stored on the server. An attacker could potentially access configuration files containing database credentials, user authentication details, application source code, or other confidential information. The vulnerability affects the integrity and confidentiality of the entire ATutor platform, as it allows for arbitrary file reading capabilities that could lead to complete system compromise. The exploit requires minimal privileges and can be executed through simple HTTP requests, making it particularly dangerous in environments where ATutor is deployed without additional security controls. This vulnerability also violates fundamental security principles of least privilege and input validation, as it demonstrates how insufficient parameter validation can lead to complete file system access.
Mitigation strategies for CVE-2016-10400 should focus on implementing proper input validation and sanitization techniques. The primary fix involves ensuring that all user-supplied input is properly validated and sanitized before being used in file system operations. This includes implementing strict path validation that prevents directory traversal sequences from being processed, using whitelist-based input validation, and ensuring that file operations are confined to predefined safe directories. Organizations should also implement proper access controls and authentication mechanisms to limit who can create or modify course icons. The recommended solution involves upgrading to ATutor version 2.2.2 or later, which includes patches specifically addressing this vulnerability. Additionally, implementing web application firewalls and input filtering rules can provide additional layers of protection against similar attacks. Regular security auditing and penetration testing should be conducted to identify and remediate similar vulnerabilities in other applications within the organization's infrastructure.