> For the complete documentation index, see [llms.txt](https://0xkourama.gitbook.io/blog/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://0xkourama.gitbook.io/blog/vulnerabilities-and-techniques/web-vulnerabilities/html-injection.md).

# HTML-Injection

## HTML Injection <a href="#html-injection" id="html-injection"></a>

<figure><img src="https://3344169606-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FjoHbOFRbwrmbD6PvIUkf%2Fuploads%2FfrNplS5sodwmfdWSmMgY%2Fimage.png?alt=media&amp;token=30f0f339-d2bd-4c55-aa17-d018db30f5e3" alt=""><figcaption><p>HTML-Injection</p></figcaption></figure>

| Content                            |
| ---------------------------------- |
| **📚 What Is HTML Injection ?**    |
| **🤔 Why HTML Injection Happen ?** |
| **⚔ Impact**                       |
| **🔎 How To Find**                 |
| **📕 Referance**                   |

***

### 📚 What Is HTML Injection? <a href="#what-is-html-injection" id="what-is-html-injection"></a>

**HTML injection** is an attack that is similar to Cross-site Scripting (XSS). While in the XSS vulnerability the attacker can inject and execute Javascript code, the HTML injection attack only allows the injection of certain HTML tags.

**HTML injection** is a type of **injection vulnerability** that occurs when a user is able to control an input point and is able to inject arbitrary **HTML code** into a vulnerable web page.

▶ You Can Know More about HTML [**HERE**](https://www.w3schools.com/html/)

***

### 🤔 Why HTML Injection Happen? <a href="#why-html-injection-happen" id="why-html-injection-happen"></a>

**This vulnerability occurs** when user **input is not correctly sanitized** and the **output is not encoded.**

For example, malicious HTML code can be injected via the **`innerHTML`** JavaScript method usually used to render user-inserted HTML code.

If strings are not correctly sanitized, the method can enable HTML injection. A JavaScript function that can be used for this purpose is **`document.write()`**.

***

### ⚔ Impact <a href="#impact" id="impact"></a>

1. It can allow an attacker to **modify** the page.
2. To **steal** another person’s **identity**.
3. The attacker discovers an injection vulnerability and decides to use an HTML injection attack.
4. The attacker **crafts malicious links**, including his **injected HTML content**, and sends it to a user **via email**.
5. **The attacker’s injected HTML** is rendered and presented to the user **asking for a username and password.**
6. **The user enters a username and password**, which are both **sent to the attacker’s server**.

***

### 🔎 How To Find <a href="#how-to-find" id="how-to-find"></a>

Like XSS and DOM-Based XSS **check** every endpoint or parameter that **accepts your HTML tags** or **source code functions that render Html Content**

***

### 📕 Reference <a href="#referance" id="referance"></a>

1. [**OWASP**](https://owasp.org/www-project-web-security-testing-guide/latest/4-Web_Application_Security_Testing/11-Client-side_Testing/03-Testing_for_HTML_Injection)
2. [**Hacktricks**](https://book.hacktricks.xyz/pentesting-web/dangling-markup-html-scriptless-injection)
3. [**Vistainfosec**](https://www.vistainfosec.com/blog/comprehensive-guide-on-html-injection/)
4. [**Acunetix**](https://www.acunetix.com/vulnerabilities/web/html-injection/)
5. [**Imperva**](https://www.imperva.com/learn/application-security/html-injection/)

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