html-injection-testing SKILL.md skillF
html-injection-testing from zebbern/claude-code-guide is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add zebbern/claude-code-guide/html-injection-testing@v1.1Pins v1.1 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- F, 15 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- zebbern/claude-code-guide
- Path
skills/html-injection-testing/SKILL.md- Versions recorded
- 3
- Latest version
- v1.1, committed May 31, 2026
- First version recorded
- Jan 4, 2026
- Size
- 13,044 bytes
- Repository stars
- 4,700
- License
- MIT
This skill should be used when the user asks to "test for HTML injection", "inject HTML into web pages", "perform HTML injection attacks", "deface web applications", or "test content injection vulnerabilities". It provides comprehensive HTML injection attack techniques and testing methodologies.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# HTML Injection Testing
## Purpose
Identify and exploit HTML injection vulnerabilities that allow attackers to inject malicious HTML content into web applications. This vulnerability enables attackers to modify page appearance, create phishing pages, and steal user credentials through injected forms.
## Prerequisites
### Required Tools
- Web browser with developer tools
- Burp Suite or OWASP ZAP
- Tamper Data or similar proxy
- cURL for testing payloads
### Required Knowledge
- HTML fundamentals
- HTTP request/response structure
- Web application input handling
- Difference between HTML injection and XSS
## Outputs and Deliverables
1. **Vulnerability Report** - Identified injection points
2. **Exploitation Proof** - Demonstrated content manipulation
3. **Impact Assessment** - Potential phishing and defacement risks
4. **Remediation Guidance** - Input validation recommendations
## Core Workflow
### Phase 1: Understanding HTML Injection
HTML injection occurs when user input is reflected in web pages without proper sanitization:
```html
<!-- Vulnerable code example -->
<div>
Welcome, <?php echo $_GET['name']; ?>
</div>
<!-- Attack input -->
…Read the whole file at its exact version.
How to install
mdr add zebbern/claude-code-guide/html-injection-testing@sha256:0698b5b945b44c0cThe line at the top of this page pins the label v1.1, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_377ufbt5jnlqsfxy)
6 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 3 versions of this file, between Jan 4, 2026 and May 31, 2026, about one every 74 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| v1.1 latest | 2026-05-31 | 164971d | 13,044 B | F | view · diff |
| v1.1 | 2026-01-20 | 27bf883 | 13,044 B | F | view · diff |
| git:20260104.9174e17 | 2026-01-04 | 9174e17 | 12,999 B | F | view |
Audit of the latest version
- FAIL, critical: No text hidden with inline styles (matched: style="background:red;color:white)
- fail: No script tag (matched: <script)
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (13044 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
Starting a new one? Use a template for SKILL.md on mdpantry, which passes every one of these checks and says what to change in it.
Source
zebbern/claude-code-guide · 4,700 stars · license MIT · pushed 2026-11-07 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_377ufbt5jnlqsfxy GET https://markdownregistry.com/api/v1/resolve?ref=zebbern/claude-code-guide/html-injection-testing GET https://markdownregistry.com/api/v1/blob/0698b5b945b44c0cad2c85e729fb003a8a814088774036d56a50cbacba5ea4c3
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.