# Ssti

> Hunt server-side template injection across Jinja2/Twig/Freemarker/Velocity/Handlebars and validate progression from expression injection to code execution.

- Skill: `purpleailab/ssti` (Agent Skill)
- Install (CLI): `npx skillmds@latest add purpleailab/ssti`
- Raw SKILL.md: https://api.skillmd.com/api/skills/purpleailab/ssti/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: purpleailab (https://skillmd.com/u/purpleailab)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/purpleailab/ssti

---


# SSTI Playbook

## High-signal checks
- Look for template rendering with user input in `render_template_string`, `Template(...)`, `twig->createTemplate`, `Freemarker Template.process`.
- Confirm user-controlled payload reaches a template context key or template source string.

## Fast probes
- Jinja2: `{{7*7}}`, `{{config}}`, `{{request}}`
- Twig: `{{7*7}}`, `{{_self}}`
- Freemarker: `${7*7}`
- Velocity: `#set($x=7*7)$x`

## Escalation path
1. Detect expression evaluation.
2. Enumerate available objects and filters.
3. Attempt file read / env leak.
4. Attempt command execution via framework-specific gadget chain.

## Validation
Use `validate_finding` with a positive execution signal and a benign negative control.