16.2 Safe from path traversal¶
Verify that untrusted file data submitted to the application is not used directly with file I/O commands, particularly to protect against path traversal, local file include, file mime type, and OS command injection vulnerabilities.
Levels: 1, 2, 3
A Path Traversal attack aims to access files and directories that are stored outside the web root folder. By browsing the application, the attacker looks for absolute links to files stored on the web server. By manipulating variables that reference files with “dot-dot-slash (../)” sequences and its variations, it may be possible to access arbitrary files and directories stored on file system, including application source code, configuration and critical system files, limited by system operational access control. The attacker uses ”../” sequences to move up to root directory, thus permitting navigation through the file system. This attack can be executed with an external malicious code injected on the path, like the Resource Injection attack. To perform this attack it’s not necessary to use a specific tool; attackers typically use a spider/crawler to detect all URLs available. This attack is also known as “dot-dot-slash”, “directory traversal”, “directory climbing” and “backtracking”. * OWASP: Path Traversal