hwl-proxy

HWL Proxy

Description

This repository contains the proof-of-concept implementation of a Header Whitelisting (HWL) Proxy. It can be deployed on HTTP intermediaries or web servers to sanitize HTTP requests from unknown or invalid header fields.

Please note: This application does not support HTTPS and is only meant for research and testing purposes.

Requirements

• Go v1.13.3 or higher

Download project

go get github.com/Digital-Security-Lab/hwl-proxy

Build

go build -o hwl-proxy

Testing

go test ./...

Run

./hwl-proxy

Optional flags

  -c string
        config file path (default "config.json")
  -wl string
        whitelist file path (default "whitelist.json")

Proxy configuration

The proxy configuration must be defined in a JSON file (default: config.json).

If deployed on an intermediary, the file may look as follows:

{
    "incomingAddress": "<host-address>:80",
    "portOutLocal": 81,
    "portInLocal": 80,
    "outgoingAddress": "<host-address>:80",
    "whitelisting": true,
    "origin": false,
    "connTimeout": 30
}

If deployed on an web server, the file may look as follows:

{
    "incomingAddress": "<host-address>:80",
    "portOutLocal": 81,
    "whitelisting": true,
    "origin": true,
    "connTimeout": 30
}

Whitelist configuration

The request header whitelist is used to define which header fields should be forwarded to the intermediary or web server. It must be specified in a JSON file (default: whitelist.json), which contains an array of {"key": "", "val": ""} objects. The value of key represents the HTTP request header field name. The val parameter is optional and can be used to limit the corresponding HTTP request header field value by a regular expression. If left out, the value can be any value that is compliant with the syntax specified in RFC 7230. The following is an example for a valid whitelist configuration:

[
    {
        "key": "host"
    },{
        "key": "content-length",
        "val": "\\d+",
    },{
        "key": "connection",
        "val": "(keep-alive|close)",
    }
]

References

• Büttner, A., Nguyen, H. V., Gruschka, N., & Lo Iacono, L. (2021). Less is Often More: Header Whitelisting as Semantic Gap Mitigation in HTTP-Based Software Systems. In IFIP International Conference on ICT Systems Security and Privacy Protection (pp. 332-347). Springer, Cham. Link

License

MIT License