Input Validation / File Path Traversal

Description

File path traversal is a type of input validation vulnerability that is categorized under the CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) in the CWE Top 25 (2022). This vulnerability occurs when an application receives input from an external source, such as a user, and does not properly restrict the input to a limited set of locations. This allows malicious users to access directories outside of the intended path, potentially leading to the disclosure of sensitive information. As described in the OWASP Testing Guide, the most common attack vector for file path traversal is through unvalidated inputs within web applications or APIs.

Risk

File path traversal can present a serious risk to any organization, as it allows malicious users to access sensitive information stored in locations that were not intended to be accessible. By accessing this information, malicious users can gain access to confidential data, such as credentials, user data, and other sensitive information. Furthermore, by accessing the underlying file system, malicious users can modify files and inject malicious code. This can potentially lead to a data breach, which can result in serious financial and reputational damage to the organization.

Solution

The best way to protect against file path traversal vulnerability is to properly validate any user input before it is processed by the application. This can be done by ensuring that user input is limited to a specific set of locations and is not allowed to access sensitive files or directories. Additionally, any user input should be filtered to remove any special characters, such as “..”, that may be used to bypass input validation. Finally, any input should be encoded or escaped to prevent malicious users from introducing malicious code into the application.