CVE-2017-10993 in Contao
Summary
by MITRE
Contao before 3.5.28 and 4.x before 4.4.1 allows remote attackers to include and execute arbitrary local PHP files via a crafted parameter in a URL, aka Directory Traversal.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 10/31/2019
The vulnerability identified as CVE-2017-10993 represents a critical directory traversal flaw in the Contao content management system that affects versions prior to 3.5.28 and 4.4.1. This vulnerability stems from insufficient input validation within the application's parameter handling mechanisms, specifically when processing URL parameters that reference local file paths. The flaw enables remote attackers to manipulate file inclusion functions by crafting malicious URLs that exploit improper path validation, allowing unauthorized access to local files and potential code execution capabilities.
The technical implementation of this vulnerability resides in the application's failure to properly sanitize and validate user-supplied input before using it in file inclusion operations. When Contao processes a URL parameter that should reference a legitimate resource, attackers can manipulate the parameter to traverse directory structures and access files outside the intended scope. This occurs due to the absence of proper path normalization and validation checks that would normally prevent attackers from specifying arbitrary file paths. The vulnerability is categorized under CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with the ability to execute arbitrary PHP code on the affected system. Successful exploitation can lead to complete system compromise, data theft, unauthorized access to sensitive information, and potential lateral movement within network environments. Attackers can leverage this vulnerability to access configuration files containing database credentials, application secrets, and other sensitive data that could be used for further attacks. The remote nature of this vulnerability means that attackers do not require local access or credentials to exploit the flaw, making it particularly dangerous in publicly accessible web applications.
The attack surface for this vulnerability extends beyond simple file access to include potential privilege escalation and persistence mechanisms. According to ATT&CK framework concepts, this vulnerability maps to T1059.007 for PHP execution and T1083 for file and directory discovery, while also enabling techniques such as T1078 for valid accounts and T1566 for spearphishing with a link. Organizations running affected Contao versions face significant risk of data breaches, system compromise, and regulatory compliance violations. The vulnerability demonstrates the critical importance of input validation and proper access controls in web applications, particularly those handling user-supplied data in file operations.
Mitigation strategies for this vulnerability require immediate patching of affected Contao installations to versions 3.5.28 or 4.4.1, which contain the necessary security fixes. Organizations should also implement network-level protections such as web application firewalls that can detect and block malicious path traversal attempts. Additional defensive measures include restricting file inclusion functions, implementing proper input sanitization, and conducting regular security audits of web applications. The vulnerability highlights the necessity of following secure coding practices and maintaining up-to-date security patches, as outlined in OWASP Top Ten and NIST cybersecurity guidelines for preventing directory traversal attacks and similar path manipulation vulnerabilities.