What is Path Equivalence (CWE-52)?

Callout

TL;DR:

Path Equivalence (CWE-52) is a type of path traversal vulnerability that occurs when an application fails to properly validate and canonicalize user-input paths. To fix this issue, you should implement input validation, canonicalization, and secure coding practices.

At-a-Glance

What is Path Equivalence?

Path Equivalence (CWE-52) is a type of path traversal vulnerability that occurs when an application fails to properly validate and canonicalize user-input paths. As defined by the MITRE Corporation under CWE-52, and classified by the OWASP Foundation under A03:2021 - Injection…

Quick Summary

Path Equivalence (CWE-52) is a high-severity vulnerability that can allow attackers to traverse the file system to unintended locations or access arbitrary files. This vulnerability occurs when an application fails to properly validate and canonicalize user-input paths. To fix this issue, you should implement input validation, canonicalization, and secure coding practices in your application.

Jump to: TL;DR: · What is Path Equivalence? · Quick Summary · Path Equivalence Overview · How Path Equivalence Works · Business Impact of Path Equivalence · Path Equivalence Attack Scenario · How to Detect Path Equivalence · How to Fix Path Equivalence · Framework-Specific Fixes for Path Equivalence · How to Ask AI to Check Your Code for Path Equivalence · Path Equivalence Best Practices Checklist · Path Equivalence FAQ · Vulnerabilities Related to Path Equivalence · References · Scan Your Own Site

Path Equivalence Overview

What: Path Equivalence (CWE-52) is a type of path traversal vulnerability that occurs when an application fails to properly validate and canonicalize user-input paths. Why it matters: This vulnerability can allow attackers to traverse the file system to unintended locations or access arbitrary files, leading to unauthorized access, modification, and potential data breaches. Where it occurs: Path Equivalence (CWE-52) typically occurs in web applications, APIs, and web services that handle user-input paths. Who is affected: Any application that fails to properly validate and canonicalize user-input paths can be affected by this vulnerability. Who is NOT affected: Applications that never construct paths/queries/commands from external input are not affected by this vulnerability.

How Path Equivalence Works

Root Cause

The root cause of Path Equivalence (CWE-52) is the failure to properly validate and canonicalize user-input paths in an application.

Attack Flow

1. An attacker sends a malicious request with a manipulated path to the vulnerable application.
2. The application fails to properly validate and canonicalize the user-input path, allowing the attacker to traverse the file system to unintended locations or access arbitrary files.
3. The attacker can then exploit this vulnerability to gain unauthorized access, modify files or directories, or disrupt the availability of the application.

Prerequisites to Exploit

For an attacker to successfully exploit Path Equivalence (CWE-52), they must:

• Be able to send a malicious request with a manipulated path to the vulnerable application.
• The application must fail to properly validate and canonicalize user-input paths.

Vulnerable Code

import os

path = request.args.get('path')
os.chdir(path)

This code demonstrates how an attacker can manipulate the path variable to traverse the file system to unintended locations or access arbitrary files.

Secure Code

import os

path = request.args.get('path')
if not os.path.abspath(path).startswith(base_dir):
    raise ValueError("Invalid path")
os.chdir(path)

This code demonstrates how an application can properly validate and canonicalize user-input paths to prevent Path Equivalence (CWE-52).

Business Impact of Path Equivalence

Confidentiality: Unauthorized access to files or directories can lead to data breaches, compromising sensitive information. Integrity: Modification of files or directories can disrupt the integrity of the application and its data. Availability: Disruption of the availability of the application can impact business operations and revenue.

Path Equivalence Attack Scenario

1. An attacker sends a malicious request with a manipulated path to the vulnerable application.
2. The application fails to properly validate and canonicalize user-input paths, allowing the attacker to traverse the file system to unintended locations or access arbitrary files.
3. The attacker can then exploit this vulnerability to gain unauthorized access, modify files or directories, or disrupt the availability of the application.

How to Detect Path Equivalence

Manual Testing

• Review code for input validation and canonicalization practices.
• Test application with malicious requests containing manipulated paths.
• Verify that the application properly validates and canonicalizes user-input paths.

Automated Scanners (SAST / DAST)

Automated scanners can detect Path Equivalence (CWE-52) by identifying vulnerabilities in code and configuration. However, dynamic analysis is required to determine the actual impact of this vulnerability.

PenScan Detection

PenScan’s automated scanning engines actively test for Path Equivalence (CWE-52).

False Positive Guidance

A finding on a filesystem operation where the path is entirely fixed and developer-controlled (never built from or influenced by external input) is a false positive — the weakness requires an attacker to be able to supply an alternate-but-equivalent form (trailing dots/slashes, case variation, 8.3 short names) of a path the application trusts.

How to Fix Path Equivalence

• Implement input validation and canonicalization practices in your application.
• Use secure coding practices to prevent Path Equivalence (CWE-52).
• Regularly review and update code to ensure that it remains secure.

Framework-Specific Fixes for Path Equivalence

Java

import java.io.File;

String path = request.getParameter("path");
if (!new File(path).isAbsolute()) {
    throw new RuntimeException("Invalid path");
}

Node.js

const path = require('path');

let path = req.params.path;
if (!path.isAbsolute()) {
    throw new Error("Invalid path");
}

Python/Django

import os

path = request.GET.get('path')
if not os.path.abspath(path).startswith(base_dir):
    raise ValueError("Invalid path")

How to Ask AI to Check Your Code for Path Equivalence

Review the following [language] code block for potential CWE-52 Path Equivalence vulnerabilities and rewrite it using canonicalization: ```python import os

path = request.args.get(‘path’) os.chdir(path) ```

Path Equivalence Best Practices Checklist

✅ Implement input validation and canonicalization practices in your application. ✅ Use secure coding practices to prevent Path Equivalence (CWE-52). ✅ Regularly review and update code to ensure that it remains secure.

Path Equivalence FAQ

How is Path Equivalence related to path traversal?

Path Equivalence (CWE-52) is a type of path traversal vulnerability that occurs when an application fails to properly validate and canonicalize user-input paths.

What are the common consequences of Path Equivalence?

The common consequences of Path Equivalence include unauthorized access to files or directories, modification of files or directories, and potential data breaches.

How can I detect Path Equivalence in my application?

You can detect Path Equivalence by using manual testing methods such as code review and fuzz testing, as well as automated scanning tools like PenScan.

What are the best practices for preventing Path Equivalence?

The best practices for preventing Path Equivalence include input validation, canonicalization, and secure coding practices.

Can AI assist in detecting and preventing Path Equivalence?

Yes, AI can assist in detecting and preventing Path Equivalence by providing automated scanning and code review capabilities.

What are the related vulnerabilities to Path Equivalence?

The related vulnerabilities to Path Equivalence include CWE-41 (Improper Resolution of Path Equivalence), CWE-163 (Improper Neutralization of Multiple Trailing Special Elements), and CWE-289 (Authentication Bypass by Alternate Name).

Vulnerabilities Related to Path Equivalence

References

• MITRE: CWE-52
• CAPEC: None known
• NVD

Scan Your Own Site

Manual code review catches what you know to look for. An automated scan catches what you didn’t. Scan your own website using PenScan to find Path Equivalence and other risks before an attacker does.