ssti-server-side-template-injection

ssti-server-side-template-injection is a skill for Claude Code, Codex from DorianGallo/hack-skills-local. It costs 36 tokens per session (3,301 once invoked), scanned B, a copy of ssti-server-side-template-injection, MIT.

A guide to finding and testing server-side template injection, a flaw where a web server evaluates user-controlled template text as code.

In plain words
What is it for?
Use it to probe template expressions, identify the template engine in use, and assess authorized injection paths.
Why use it?
It helps reveal when preview pages, server-rendered views, or template engines can turn untrusted input into unintended server actions.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to probe template expressions, identify the template engine in use, and assess authorized injection paths.

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Install with agentmods
npx agentmods add skills/doriangallo/hack-skills-local/ssti-server-side-template-injection
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add DorianGallo/hack-skills-local --skill ssti-server-side-template-injection
Clone the repo
git clone --depth 1 https://github.com/DorianGallo/hack-skills-local

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for ssti-server-side-template-injection

README.md
[![agentmods](https://agentmods.dev/badge/skills/doriangallo/hack-skills-local/ssti-server-side-template-injection/github.svg)](https://agentmods.dev/skills/doriangallo/hack-skills-local/ssti-server-side-template-injection)
Your own site
<a href="https://agentmods.dev/skills/doriangallo/hack-skills-local/ssti-server-side-template-injection"><img src="https://agentmods.dev/badge/skills/doriangallo/hack-skills-local/ssti-server-side-template-injection/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for ssti-server-side-template-injection

Your own site · 80×15
<a href="https://agentmods.dev/skills/doriangallo/hack-skills-local/ssti-server-side-template-injection"><img src="https://agentmods.dev/badge/skills/doriangallo/hack-skills-local/ssti-server-side-template-injection.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 36 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,301 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 2 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00036 $0.03301
Opus 5 $0.00018 $0.01650
Sonnet 5 $0.00007 $0.00660
Haiku 4.5 $0.00004 $0.00330

Measured 7d ago against content hash f03a7bd241d7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade B, and why

ssti-server-side-template-injection scanned grade B with 2 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 7d 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.

3. `cat ~/.aws/credentials` — cloud credentials

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

# Find subprocess.Popen index (usually around 258-270, varies by Python version):
Origin

This is a copy

100% identical to ssti-server-side-template-injection — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/ssti-server-side-template-injection/SKILL.md · 345 lines

How it starts

The opening of the file, as written. The whole thing — 345 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SKILL: Server-Side Template Injection (SSTI) — Expert Attack Playbook

AI LOAD INSTRUCTION: Expert SSTI techniques. Covers polyglot detection probes, engine fingerprinting, Jinja2/FreeMarker/Twig/ERB RCE chains, client-side Angular SSTI, and bypass techniques. Base models often miss sandbox escape MRO chains and non-Jinja2 engines. For PHP CMS template eval, Jira SSTI, Confluence OGNL, and Spring Cloud Gateway SpEL, load the companion SCENARIOS.md.

Before using full engine-specific exploitation, you can first load:

  • First use the polyglot probe sequence at the top of this file for low-noise fingerprinting
  • expression-language-injection when ${7*7} or %{7*7} resolves in Java (SpEL/OGNL) — different attack surface from template engines

Extended Scenarios

Also load SCENARIOS.md when you need:

  • Maccms 8.x PHP template eval{if-A:phpinfo()}{endif-A} in vod-search, base64 bypass for webshell write
  • Jira CVE-2019-11581 — "Contact Administrators" form → Velocity template injection → command output in admin email
  • Spring Cloud Gateway SpEL (CVE-2022-22947) — actuator route injection with StreamUtils.copyToByteArray for output capture
  • Struts2 OGNL S2-045 (CVE-2017-5638) — Content-Type header OGNL injection with _memberAccess / OgnlUtil blacklist clear
  • Confluence OGNL CVE-2021-26084 — createpage-entervariables.action with \u0027 unicode bypass
  • SSTI vs EL injection disambiguation guide
  • Additional template engines: ASP.NET Razor, Elixir EEx, PHP Smarty/Latte/Blade, JS Pug/Handlebars/Nunjucks/EJS/Lodash + universal detection + blind SSTI + Flask PIN calculation

SCENARIOS.md reference (§7–§11): For expanded payloads and engine-specific notes on Razor, EEx/LEEx/HEEx, PHP stacks, JavaScript template engines, the universal polyglot probe, mathematical fingerprinting, blind SSTI (boolean / time / OOB), and Flask debug PIN prerequisites, see SCENARIOS.md. This skill keeps a short checklist in §13–§15.

Read the full file on GitHub · 345 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

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.

  1. 7d ago First seen · 345 lines · 36 tokens per session scan B f03a7bd241d7

Subscribe to this mod's changes

ssti-server-side-template-injection is a skill published in the GitHub repository DorianGallo/hack-skills-local (5 stars, last pushed 3mo ago), licensed MIT. It adds 36 tokens to every session and 3,301 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it B with 2 findings (reaches for credential files, runs shell commands). It is 100% identical to ssti-server-side-template-injection, differing in 0 lines, and is treated as a copy.

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