GIXY

Note

Keep NGINX secure and up-to-date with maintained modules via NGINX Extras RPM repository by GetPageSpeed.

Overview

Gixy is a tool to analyze NGINX configuration. The main goal of Gixy is to prevent security misconfiguration and automate flaw detection.

Currently supported Python versions are 3.6 through 3.13.

Disclaimer: Gixy is well tested only on GNU/Linux, other OSs may have some issues.

What it can do

Right now Gixy can find:

• [ssrf] Server Side Request Forgery
• [http_splitting] HTTP Splitting
• [origins] Problems with referrer/origin validation
• [add_header_redefinition] Redefining of response headers by "add_header" directive
• [host_spoofing] Request's Host header forgery
• [valid_referers] none in valid_referers
• [add_header_multiline] Multiline response headers
• [alias_traversal] Path traversal via misconfigured alias
• [if_is_evil] If is evil when used in location context
• [allow_without_deny] Allow specified without deny
• [add_header_content_type] Setting Content-Type via add_header
• [resolver_external] Using external DNS nameservers
• [version_disclosure] Using insecure values for server_tokens
• [try_files_is_evil_too] The try_files directive is evil without open_file_cache
• [proxy_pass_normalized] proxy_pass will decode and normalize paths when specified with a path
• [worker_rlimit_nofile_vs_connections] worker_rlimit_nofile must be at least twice worker_connections
• [error_log_off] error_log set to off
• [unanchored_regex] Regular expression without anchors
• [regex_redos] Regular expressions may result in easy denial-of-service (ReDoS) attacks

You can find things that Gixy is learning to detect at Issues labeled with "new plugin"

Installation

CentOS/RHEL and other RPM-based systems

yum -y install https://extras.getpagespeed.com/release-latest.rpm
yum -y install gixy

Other systems

Gixy is distributed on PyPI. The best way to install it is with pip:

pip install gixy-ng

Usage

By default, Gixy will try to analyze NGINX configuration placed in /etc/nginx/nginx.conf.

But you can always specify the needed path:

$ gixy /etc/nginx/nginx.conf

==================== Results ===================

Problem: [http_splitting] Possible HTTP-Splitting vulnerability.
Description: Using variables that can contain "\n" may lead to http injection.
Additional info: https://github.com/dvershinin/gixy/blob/master/docs/en/plugins/httpsplitting.md
Reason: At least variable "$action" can contain "\n"
Pseudo config:
include /etc/nginx/sites/default.conf;

	server {

		location ~ /v1/((?<action>[^.]*)\.json)?$ {
			add_header X-Action $action;
		}
	}


==================== Summary ===================
Total issues:
    Unspecified: 0
    Low: 0
    Medium: 0
    High: 1

Or skip some tests:

$ gixy --skips http_splitting /etc/nginx/nginx.conf

==================== Results ===================
No issues found.

==================== Summary ===================
Total issues:
    Unspecified: 0
    Low: 0
    Medium: 0
    High: 0

Or something else, you can find all other gixy arguments with the help command: gixy --help

Plugin options

Some plugins expose options which you can set via CLI flags or config file. CLI flags follow the pattern --<PluginName>-<option> with dashes, while config file uses [PluginName] sections with dashed keys.

• origins:

  • --origins-domains domains: Comma-separated list of trusted registrable domains. Use * to disable third‑party checks. Example: --origins-domains example.com,foo.bar. Default: *.
  • --origins-https-only true|false: When true, only the https scheme is considered valid for Origin/Referer. Default: false.
  • --origins-lower-hostname true|false: Normalize hostnames to lowercase before validation. Default: true.

• add_header_redefinition:

  • --add-header-redefinition-headers headers: Comma-separated allowlist of header names (case-insensitive). When set, only dropped headers from this list will be reported; when unset, all dropped headers are reported. Example: --add-header-redefinition-headers x-frame-options,content-security-policy. Default: unset (report all).

Examples (config file):

[origins]
domains = example.com, example.org
https-only = true

[add_header_redefinition]
headers = x-frame-options, content-security-policy

You can also make gixy use pipes (stdin), like so:

echo "resolver 1.1.1.1;" | gixy -

Docker usage

Gixy is available as a Docker image from the Docker hub. To use it, mount the configuration that you want to analyse as a volume and provide the path to the configuration file when running the Gixy image.

$ docker run --rm -v `pwd`/nginx.conf:/etc/nginx/conf/nginx.conf getpagespeed/gixy /etc/nginx/conf/nginx.conf

If you have an image that already contains your nginx configuration, you can share the configuration with the Gixy container as a volume.

$  docker run --rm --name nginx -d -v /etc/nginx
nginx:alpinef68f2833e986ae69c0a5375f9980dc7a70684a6c233a9535c2a837189f14e905

$  docker run --rm --volumes-from nginx dvershinin/gixy /etc/nginx/nginx.conf

==================== Results ===================
No issues found.

==================== Summary ===================
Total issues:
    Unspecified: 0
    Low: 0
    Medium: 0
    High: 0

Kubernetes usage

Given you are using the official NGINX ingress controller, not the kubernetes one, you can use this https://github.com/nginx/kubernetes-ingress

kubectl exec -it my-release-nginx-ingress-controller-54d96cb5cd-pvhx5 -- /bin/bash -c "cat /etc/nginx/conf.d/*" | docker run -i getpagespeed/gixy -

==================== Results ===================

>> Problem: [version_disclosure] Do not enable server_tokens on or server_tokens build
Severity: HIGH
Description: Using server_tokens on; or server_tokens build;  allows an attacker to learn the version of NGINX you are running, which can be used to exploit known vulnerabilities.
Additional info: https://gixy.getpagespeed.com/en/plugins/version_disclosure/
Reason: Using server_tokens value which promotes information disclosure
Pseudo config:

server {
	server_name XXXXX.dev;
	server_tokens on;
}

server {
	server_name XXXXX.dev;
	server_tokens on;
}

server {
	server_name XXXXX.dev;
	server_tokens on;
}

server {
	server_name XXXXX.dev;
	server_tokens on;
}

==================== Summary ===================
Total issues:
    Unspecified: 0
    Low: 0
    Medium: 0
    High: 4

Contributing

Contributions to Gixy are always welcome! You can help us in different ways:

• Open an issue with suggestions for improvements and errors you're facing;
• Fork this repository and submit a pull request;
• Improve the documentation.

Code guidelines:

• Python code style should follow pep8 standards whenever possible;
• Pull requests with new plugins must have unit tests for it.