AuthzLoom

I built AuthzLoom to make authorization testing easier to repeat and easier to review. You describe the identities, controlled objects and operation you want to test. AuthzLoom builds the matrix, runs it within the limits you set and keeps redacted evidence of what happened.

It works with REST and GraphQL and can be used from the command line, through MCP, through its local HTTP API or with the optional Burp Suite extension.

AuthzLoom does not decide whether something is a vulnerability and it does not assign severity. It collects evidence. The final judgment stays with the person reviewing the result.

What it protects

Authorization testing can change data, so I designed the tool around explicit limits:

• Every scenario defines its allowed hosts, methods, request budget and rate.
• Every request goes through the same policy validation, including identity probes.
• An operation that changes state must have a readback step.
• Cleanup runs after a mutation may have been sent, even when the case fails or is cancelled.
• Direct connections are limited to local labs and never follow redirects.
• Traffic to anything outside the local machine must use a Burp or CDP session controlled by the operator.
• Live credentials do not belong in scenario files. Burp keeps the original request and gives Python an opaque cap_* handle instead.
• Local runs stay local. Exported capsules are redacted and never contain raw Burp capture bytes.

Only use AuthzLoom on systems you own or have explicit permission to test.

Installation

You need Python 3.11 or newer.

On Windows:

git clone <repository-url> authzloom
cd authzloom
powershell -ExecutionPolicy Bypass -File ./setup-env.ps1 -Dev

If you already manage your own Python environment:

python -m pip install -e '.[dev]'

The optional dependency groups are yaml, cdp and dev.

Try it from the command line

The included example expects a synthetic service on 127.0.0.1:8877. Validation and planning are offline. Running the scenario requires the local lab service.

./.venv/Scripts/authzloom.exe init ./scenario.json
./.venv/Scripts/authzloom.exe validate ./examples/rest.json
./.venv/Scripts/authzloom.exe plan ./examples/rest.json --explain
./.venv/Scripts/authzloom.exe run ./examples/rest.json
./.venv/Scripts/authzloom.exe status
./.venv/Scripts/authzloom.exe export <RUN_ID> --output capsule.redacted.json
./.venv/Scripts/authzloom.exe schema > schemas/scenario.v1.json

There is also a GraphQL example in examples/graphql.json. To see structured logs without secrets, set AUTHZLOOM_LOG=1.

You can run the module directly too:

./.venv/Scripts/python.exe -m authzloom.cli --help

Using AuthzLoom with an AI client

AuthzLoom includes an MCP server:

./.venv/Scripts/authzloom.exe mcp

For an installed registry package, the canonical package launcher is:

uvx authzloom mcp

authzloom-mcp remains available as a compatibility entry point, but catalogs and managed launchers should identify the authzloom package and invoke the mcp subcommand.

MCP communicates over standard input and output. If you start it by hand, it will appear to wait silently. That is expected. Normally, your MCP client starts and controls the process:

{
  "mcpServers": {
    "authzloom": {
      "command": "C:/absolute/path/authzloom/.venv/Scripts/python.exe",
      "args": ["-m", "authzloom.cli", "mcp"],
      "env": {
        "AUTHZLOOM_DATA_DIR": "C:/absolute/path/authzloom/.authzloom"
      }
    }
  }
}

The available tools are authzloom_ingest, authzloom_plan, authzloom_run, authzloom_status and authzloom_export. Always plan a scenario before running it.

Using the Burp extension

Burp Suite is not included. Point BURP_JAR to your local Burp installation, build the extension and start the launcher:

$env:BURP_JAR = 'C:\path\to\burpsuite.jar'
powershell -ExecutionPolicy Bypass -File ./burp-extension/build.ps1
powershell -ExecutionPolicy Bypass -File ./start-authzloom-burp.ps1

Load burp-extension/build/authzloom-burp.jar through Burp's extension settings if it is not already loaded.

The launcher creates a temporary shared token, starts the local API on 127.0.0.1:8891 and opens Burp. The extension runs its replay bridge on 127.0.0.1:8892 and adds Send to AuthzLoom to Burp's context menu.

When you send a request to AuthzLoom, the live bytes stay inside Burp. Python receives the host, method, path and an opaque handle. During replay, only an allowlisted overlay is applied. Authorization and Cookie headers remain under Burp's control.

The local API provides GET /health, GET /ready and GET /version. /status accepts limit and offset. It only binds to loopback.

Development

Run the complete local check before submitting a change:

powershell -ExecutionPolicy Bypass -File ./verify-integration.ps1

Please keep the public repository independent. Private paths, client configuration, target evidence, credentials and generated run data should never be committed.

License

AuthzLoom is available under the MIT License. See LICENSE.