Augur is a dynamic taint analysis for Node.js implemented in TypeScript using NodeProf. Augur is a clean-room implementation of Ichnaea, the taint analysis described in the IEEE TSE paper: Platform-Independent Dynamic Taint Analysis for JavaScript.

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What is taint analysis?

Taint analysis is a dynamic program analysis technique used to track data flows through programs. It's useful in many domains, but the most common application of taint analysis is for detecting injection vulnerabilities. Read this paper for more background on taint analysis.

Getting started

Let's walk through how to install Augur and use it to analyze a Node.js project.

First, clone this project onto your machine:

$ git clone --recurse-submodules https://github.com/nuprl/augur
$ cd augur/ts

Next, build NodeProf and Augur:

$ ./docker-nodeprof/docker-build.sh # Build NodeProf
$ npm install                       # Install Augur deps
$ npm run build                     # Build Augur

Try running a basic test to make sure your installation succeeded:

$ jest -t basic-assignment-tainted
tainted value flowed into sink {"type":"variable","name":"z","location":{"fileName":"test.js"}}!

Your Augur installation is now set up!

Instrumenting an application

Using Augur to analyze your own applications simply requires placing a file, spec.json, at the root of your Node.js project:

{
    "main": "test.js",
    "sources": [
        {
            "type": "functionReturn",
            "name": "readFileSync"
        }
    ],
    "sinks": [
        {
            "type": "functionInvocation",
            "name": "exec"
        }
    ]
}

This file tells Augur the sources and sinks of the flows you want to track. The spec above tells Augur to alert you if any value returned from readFileSync flows into the function exec. It also tells Augur how to run your project: by executing the file test.js.

Let's say we analyze the following program, test.js:

const fs = require('fs');
const child_process = require('child_process');

// read in user's message from a file
let input = fs.readFileSync("message.txt");

// echo the user's message
child_process.exec("echo 'User\'s message: " + input + "'");

This exact flow is a classic example of an injection vulnerability: exec is a very powerful function, giving the command full control over your machine; and readFileAsync returns arbitrary user input, meaning the user may have full control of your machine. This can cause massive security issues, as well as bugs with disastrous consequences.

Let's go ahead and use Augur to verify that there is indeed a taint flow between user input and exec.

Our project is structured like this:

project/
|
+-- test.js
|
+-- message.txt
|
+-- spec.json

This example is also a real test case in Augur.

To analyze this project with Augur, we run:

$ cd augur/ts
$ node ./runner/cli.js ~/project project .
           #           ^^^^^^^^^ ^^^^^^^ ^
           #     path to project    |    |
           #                        |    |
           #             project name    |
           #                             |
           # directory to store temp files

Augur will alert us that the application does in fact have the flow we're expecting:

Flows found into the following sinks: [
    {
        "type": "functionInvocation",
        "name": "exec"
    }
]

You've now analyzed your first application using Augur!

Native function models

Modern JavaScript relies on a wide variety of native functions to improve its usability and performance. Common operations on data structures and utilities are now natively implemented in the VM, including array reduce, promises, and regular expressions.

Because native functions are so pervasive, accurately tracking taint in modern JavaScript requires an understanding of these functions. Our taint analysis only analyzes JavaScript code, so we can't instrument the actual implementations of these native functions. Our taint analysis supports two ways of tracking taint through these native functions:

1. implementing native models. A native model is an implementation of a native function that only tracks taint. It doesn't have to perform any logical calculations, it just has to inform the abstract machine where taint should flow as a result of the function call. These models are often much easier to implement than the functions themselves because data flows are often more simple than the logic in a function. For examples of native models, look at src/native/native.ts.
2. using polyfills. Polyfills are implementations of native functions written in JavaScript itself. While polyfills are traditionally used for providing missing functionality to older web browsers, they can also help the taint analysis understand data-flow. If you want to track data-flow through a native function that you can write a polyfill for, use it normally in src/native/polyfill.ts.

Optional: Installing NodeProf locally

Augur normally runs your Node.js project in Docker. This is because NodeProf is difficult to install and configure locally. If you want to avoid using Docker, you can install NodeProf locally and point Augur to the installation.

To install NodeProf locally, follow the advanced installation instructions.

When using a manual installation, you will have to set environment variables:

• NODEPROF_HOME: pointing to your NodeProf advanced installation
• JAVA_HOME: pointing to your JVM CI directory (not the bin subdirectory)
• MX_HOME: pointing to your mx installation

Example:

• NODEPROF_HOME=/home/mwaldrich/workspace-nodeprof/nodeprof.js/
• MX_HOME=/home/mwaldrich/mx
• JAVA_HOME=/home/mwaldrich/openjdk1.8.0_172-jvmci-0.46

Augur will automatically use a local NodeProf installation if these environment variables are set; no flags or further configuration is needed.

Contributing to Augur

If you're looking to dive into Augur's code, the structure and implementation of the analysis is documented with READMEs in folders inside src.

If you want to contribute to Augur, we recommend using JetBrain's WebStorm IDE. To get the project fully up and running, simply:

1. follow the installation instructions in the Getting started section
2. open the augur folder in WebStorm
3. execute the Run Configuration named unit tests

JavaScript Feature Support

	Not Yet	In Progress	Done	Notes
Variable read			x
Variable write			x
Property read			x
Property write			x
Unary expression			x
Binary expression			x
Implicit declaration of this			x	see #19
Function declaration			x
Function arguments			x
Variable assignment			x	see #20
Function call			x	see #21
Native functions			x	see #22
Async/await	x			see #29
Function returns			x	see #30

Support for Ichnaea Benchmarks

Ichnaea was evaluated against a set of 22 benchmarks. Here is a table showing how Augur performs on these benchmarks:

	Correct Output	Incorrect Output	Old/Broken Code
chook-growl-reporter-exec	x
cocos-utils	x
fish-exec	x
git2json-exec	x
gm-attack	x
growl-exec	x
libnotify-exec	x
m-log-eval		x
mixin-pro-eval	x
modulify-eval	x
mongo-parse-eval	x
mongoosemask-eval	x
mongoosify-eval	x
node-os-utils	x
node-wos	x
office-converter	x
os-uptime	x
osenv	x
pidusage-exec			x
pomelo-monitor	x
system-locale	x
systeminformation	x

The benchmark pidusage-exec crashes in modern JavaScript VMs.

The benchmark m-log-eval is not currently compatible with the tool due to a missing native function model.

Acknowledgments

Augur was written by Mark Aldrich, Emily Shi, Alexi Turcotte, and Frank Tip.

Augur sits on top of NodeProf, the dynamic analysis framework written by Haiyang Sun and others.

Augur also relies on Oracle's GraalVM and GraalJS.

This research was supported by the National Science Foundation under NSF grant CCF-1715153 and REU supplement CCF-1930604.

Copyright (c) 2019-2020 Programming Research Lab at Northeastern University. Augur is licensed under the UPL. See the LICENSE file for more information.