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Jul 27, 2017

Second Order

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


Go version >= 1.8 is required.

go get

This will download the code, compile it, and leave a second-order binary in $GOPATH/bin.

Command line options

 -base string
       Base link to start scraping from (default "")
 -config string
       Configuration file (default "config.json")
       Print visited links in real-time to stdout
 -output string
       Directory to save results in (default "output")


go run second-order.go -base -config config.json -output -concurrency 10

Configuration File

Example configuration file included (config.json)

  • Headers: A map of headers that will be sent with every request.
  • Depth: Crawling depth.
  • LogCrawledURLs: If this is set to true, Second Order will log the URL of every crawled page.
  • 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.
  • LogURLRegex: A list of regular expressions that will be matched against the URLs that are extracted using the queries in LogQueries; if left empty, all URLs will be logged.
  • LogNon200Queries: A map of tag-attribute queries that will be searched for in crawled pages, and logged only if they don't return a 200 status code.
  • ExcludedURLRegex: A list of regular expressions whose matching URLs will not be accessed by the tool.
  • ExcludedStatusCodes: A list of status codes; if any page responds with one of these, it will be excluded from the results of LogNon200Queries; if left empty, all non-200 pages' URLs will be logged.
  • LogInlineJS: If this is set to true, Second Order will log the contents of every script tag that doesn't have a src attribute.

Output Directory Structure

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

      logged-queries.json         -> The results of `LogQueries`
      logged-non-200-queries.json -> The results of `LogNon200Queries`
      inline-scripts.json         -> The results of `LogInlineJS`

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. (Duh!)
  • Collect JS code by setting LogInlineJS to true, and adding "script": "src" to LogQueries.
  • Find a target's online assets by using LogURLRegex. (S3 buckets, anyone?)
  • Collect SWF files by adding "object": "src" to LogQueries.
  • Collect <input> names by adding "input": "name" to LogQueries.



Second-order subdomain takeover scanner



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