[ttml2] Link Vulnerability (#1280)

Alpop12 has just created a new issue for https://github.com/w3c/ttml2:

== Link Vulnerability ==
A link vulnerability refers to a security issue that occurs when external resources (such as files, libraries, or scripts) are linked or included in an insecure manner, potentially allowing attackers to exploit them to carry out attacks such as content injection, directory traversal, or remote code execution.

---

### Examples of link vulnerabilities:
1. Linking to untrusted external files:
- If a website loads libraries (such as JavaScript or CSS) from external links without verifying their integrity, an attacker may inject malicious code.  - Example:
```html
<script src="https://example.com/malicious-script.js"></script>
```

2. **Directory Traversal**:
- When using user input to create file paths without filtering them, an attacker may be able to access sensitive files.
- Example:
```
https://example.com/load?file=../../etc/passwd
```

3. **Include/Require Vulnerabilities (in PHP, for example)**:
- If a function like `include()` or `require()` is used with user input without validation, malicious files may be included.
- Example:
```php
include($_GET['page'] . '.php');  // Vulnerability: ?page=malicious-code
```

4. **Unsecured File Uploads**:
- If a site allows files to be uploaded without verifying their type or content, executable files (such as `.php` or `.exe`) may be uploaded.

---
### **How ​​to exploit the vulnerability:**
- **JavaScript/HTML Code Injection** (XSS):
- If an external script is linked, an attacker can steal user data (such as cookies).
- **Local File Inclusion - LFI**:
- Reading files such as `/etc/passwd` on Linux systems.
- **Remote Command Execution** (RCE):
- If a malicious PHP file is included, commands can be executed on the server.

---

### **Prevention of the vulnerability:**
1. **Do not rely on user input** to create file paths.
 2. **Disable remote inclusion** (in PHP: `allow_url_include=Off`).
3. **Filter input** (e.g., using `basename()` in PHP to remove `../`).
4. **Use a whitelist** of files that are allowed to be linked.
5. **Update libraries and external links** periodically.

---
### **Practical prevention example (PHP):**
```php
// Unsafe method:
include($_GET['page']);

// Safe method (using whitelist):
$allowed_pages = ['home.php', 'about.php'];
if (in_array($_GET['page'], $allowed_pages)) {
include($_GET['page']);
} else {
die('Page not allowed!');
 }
```


https://www.w3.org/2007/09/13-html-wg-irc.txt

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Please view or discuss this issue at https://github.com/w3c/ttml2/issues/1280 using your GitHub account


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Received on Saturday, 29 March 2025 12:43:45 UTC