Second-Order – Subdomain Takeover Scanner

Scans web applications for second-order subdomain takeover by crawling the app, and collecting URLs (and other data) that match certain rules, or respond in a certain way.

Installation

From binary

Download a prebuilt binary from the releases page and unzip it.

From source

Go version 1.17 is recommended.

go install -v github.com/mhmdiaa/second-order@latest

Docker

docker pull mhmdiaa/second-order

Command line options

  -target string
        Target URL
  -config string
        Configuration file (default "config.json")
  -depth int
        Depth to crawl (default 1)
  -header value
    	Header name and value separated by a colon 'Name: Value' (can be used more than once)
  -insecure
        Accept untrusted SSL/TLS certificates
  -output string
        Directory to save results in (default "output")
  -threads int
        Number of threads (default 10)

Configuration File

Example configuration files are in config

• LogQueries: A map of tag-attribute queries that will be searched for in crawled pages. For example, "a": "href" means log every href attribute of every a tag.
• LogNon200Queries: A map of tag-attribute queries that will be searched for in crawled pages, and logged only if they contain a valid URL that doesn’t return a 200 status code.
• LogInline: A list of tags whose inline content (between the opening and closing tags) will be logged, like title and script

Output

All results are saved in JSON files that specify what and where data was found

• The results of LogQueries are saved in attributes.json

{
    "https://example.com/": {
        "input[name]": [
            "user",
            "id",
            "debug"
        ]
    }
}

• The results of LogNon200Queries are saved in non-200-url-attributes.json

{
    "https://example.com/": {
        "script[src]": [
            "https://cdn.old_abandoned_domain.com/app.js",
        ]
    }
}

• The results of LogInline are saved in inline.json

{
    "https://example.com/": {
        "title": [
            "Example - Home"
        ]
    },
      "https://example.com/login": {
        "title": [
            "Example - login"
        ]
    }
}

Usage Ideas

This is a list of tips and ideas (not necessarily related to second-order subdomain takeover) on what to use Second Order for.

• Check for second-order subdomain takeover: takeover.json. (Duh!)
• Collect inline and imported JS code: javascript.json.
• Find where a target hosts static files cdn.json. (S3 buckets, anyone?)
• Collect <input> names to build a tailored parameter bruteforcing wordlist: parameters.json.
• Feel free to contribute more ideas!

References

https://shubs.io/high-frequency-security-bug-hunting-120-days-120-bugs/#secondorder

https://edoverflow.com/2017/broken-link-hijacking/