What is Path Equivalence (CWE-53)?

TL;DR: A successful Path Equivalence attack can result in unauthorized access to sensitive files and compromised system integrity. To prevent these attacks, implement secure coding practices, validate path input, and regularly update dependencies.

At-a-Glance

What is Path Equivalence?

Path Equivalence (CWE-53) is a type of vulnerability that occurs when an application fails to properly validate path input. This can allow attackers to traverse the file system and access sensitive files.

As defined by the MITRE Corporation under CWE-53, and classified by the OWASP Foundation under No official mapping…

Quick Summary

Path Equivalence attacks occur when an application fails to properly validate path input, allowing attackers to traverse the file system and access sensitive files. These attacks can result in unauthorized access to sensitive files, data breaches, and compromised system integrity.

Jump to: 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 occurs when an application fails to properly validate path input.
• Why it matters: A successful Path Equivalence attack can result in unauthorized access to sensitive files, data breaches, and compromised system integrity.
• Where it occurs: Path Equivalence attacks typically occur in web applications and web services that handle user-inputted paths.
• Who is affected: Any application or service that fails to properly validate path input is vulnerable to Path Equivalence attacks.
• Who is NOT affected: Applications that never construct paths/queries/commands from external input are not vulnerable.

How Path Equivalence Works

Root Cause

Path Equivalence occurs when an application fails to properly validate path input, allowing attackers to traverse the file system and access sensitive files.

Attack Flow

1. An attacker submits a malicious path input to the application.
2. The application processes the path input without proper validation.
3. The attacker gains unauthorized access to sensitive files or data.

Prerequisites to Exploit

• The application must handle user-inputted paths.
• The application must fail to properly validate path input.

Vulnerable Code

import os

path = request.form['path']
os.chdir(path)

This code is vulnerable because it fails to properly validate the path variable, which can be controlled by an attacker. This allows the attacker to traverse the file system and access sensitive files.

Secure Code

import os

base_dir = '/allowed/base/directory'
path = request.form['path']

if not os.path.abspath(path).startswith(base_dir):
    raise ValueError('Invalid path')
else:
    os.chdir(path)

This code is secure because it properly validates the path variable against a set of allowed values.

Business Impact of Path Equivalence

• Confidentiality: A successful Path Equivalence attack can result in unauthorized access to sensitive files and data breaches.
• Integrity: A successful Path Equivalence attack can result in compromised system integrity, allowing attackers to modify or delete sensitive files.
• Availability: A successful Path Equivalence attack can result in downtime or denial-of-service attacks.

Some real-world business consequences of a Path Equivalence attack include:

• Financial losses due to data breaches and compromised system integrity
• Compliance fines for failing to protect sensitive data
• Reputation damage due to public disclosure of the attack

Path Equivalence Attack Scenario

1. An attacker submits a malicious path input to the application.
2. The application processes the path input without proper validation.
3. The attacker gains unauthorized access to sensitive files or data.

How to Detect Path Equivalence

Manual Testing

• Check for user-inputted paths in the application code
• Verify that path input is properly validated against a set of allowed values
• Test the application with malicious path inputs to ensure proper validation

Automated Scanners (SAST/DAST)

• Use static analysis tools to identify potential vulnerabilities in the application code
• Use dynamic testing tools to simulate attacks and identify potential vulnerabilities

PenScan Detection

PenScan’s scanner engines can detect Path Equivalence vulnerabilities by analyzing the application code for potential vulnerabilities.

False Positive Guidance

When reviewing findings from automated scanners or manual testing, consider the following:

• If the pattern looks risky but is actually safe due to context a scanner can’t see, it may be a false positive.
• If the pattern is actually malicious but is not exploitable in the current environment, it may be a false positive.

How to Fix Path Equivalence

• Implement input validation to ensure that path input is properly validated against a set of allowed values
• Use secure coding practices to prevent vulnerabilities
• Regularly update dependencies to ensure that any known vulnerabilities are patched

Framework-Specific Fixes for Path Equivalence

Java

String baseDir = "/allowed/base/directory";
String path = request.getParameter("path");

if (!path.startsWith(baseDir)) {
    throw new ServletException("Invalid path");
}

Node.js

const express = require('express');
const app = express();

app.use(express.static('/allowed/base/directory'));

const path = req.query.path;
if (!path.startsWith('/allowed/base/directory/')) {
    res.status(400).send('Invalid path');
}

Python/Django

from django.http import HttpResponse

base_dir = '/allowed/base/directory'
path = request.GET.get('path')

if not path.startswith(base_dir):
    return HttpResponse('Invalid path', status=400)

PHP

$baseDir = '/allowed/base/directory';
$path = $_GET['path'];

if (!strpos($path, $baseDir) === 0) {
    header('HTTP/1.1 400 Bad Request');
}

How to Ask AI to Check Your Code for Path Equivalence

You can use a copy-pasteable prompt with an AI assistant to review your code and identify potential vulnerabilities related to Path Equivalence.

Path Equivalence Best Practices Checklist

✅ Validate path input against a set of allowed values ✅ Use secure coding practices to prevent vulnerabilities ✅ Regularly update dependencies to ensure that any known vulnerabilities are patched

Path Equivalence FAQ

How does Path Equivalence work?

Path Equivalence occurs when an application fails to properly validate path input, allowing attackers to traverse the file system and access sensitive files.

What are the consequences of a Path Equivalence attack?

A successful Path Equivalence attack can result in unauthorized access to sensitive files, data breaches, and compromised system integrity.

How do I detect Path Equivalence vulnerabilities?

You can use manual testing, automated scanners (SAST/DAST), or PenScan’s detection capabilities to identify potential Path Equivalence vulnerabilities.

What are the common mitigations for Path Equivalence?

Common mitigations include input validation, canonicalization, and secure coding practices.

Can AI help me prevent Path Equivalence attacks?

Yes, you can use AI-powered tools to review your code and identify potential vulnerabilities related to Path Equivalence.

What are some best practices for preventing Path Equivalence attacks?

Best practices include validating path input, using secure coding practices, and regularly updating dependencies.

Can I ask an AI assistant to check my code for Path Equivalence vulnerabilities?

Yes, you can use a copy-pasteable prompt with an AI assistant to review your code and identify potential vulnerabilities related to Path Equivalence.

Vulnerabilities Related to Path Equivalence

References

• MITRE CWE-53
• 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.