Conduct search engine discovery/reconnaissance for information leakage (OTG-INFO-001)

OWASP Testing Guide v3 Table of Contents

This article is part of the OWASP Testing Guide v3. The entire OWASP Testing Guide v3 can be downloaded here.

OWASP at the moment is working at the OWASP Testing Guide v4: you can browse the Guide here

This is a draft of a section of the new Testing Guide v3

Brief Summary

This section describes how to retrieve and remove the web content stored by the Google Cache of the application being tested.

This procedure is applicable to other Search Engines such as Live, Yahoo!, etc.

Description of the Issue

When web content is indexed by Google their Crawler referred to as "Googlebot" refers to the robots.txt file in the web root directory.

If the robots.txt file is not revised during changes to web content, then it is possible for web content not intended to be included in Google's Search Results to be indexed by Google.

Therefore, this web content must be removed from the Google Cache.

Black Box Testing

The Advanced "site:" Search Operator of Google restricts its Search Results to a specific domain.

Google provides the Advanced "cache:" Search Operator but this is the equivalent of clicking the "Cached" link of individual Google Search Results. Hence, the use of the Advanced "site:" Search Operator is advocated.

Example

To find the web content of http://www.owasp.org indexed by Google Cache the following Google Search Query is issued:

site:owasp.org

Remediation

If the removal is not urgent then simply modifying the robots.txt file to "Disallow:" this content will result in its removal from the index once Googlebot has completed crawling the web site.

For urgent removal, Google provide the "URL Removal" function as part of their "Google Webmaster Tools" service.

Gray Box testing and example

Grey Box testing is the same as Black Box testing above

References

Whitepapers
"Against the System: Rise of the Robots" - Michal Zalewski - http://www.phrack.org/issues.html?issue=57&id=10#article

Tools
Google SOAP Search API - http://code.google.com/apis/soapsearch/
Google Hacking Database (GHDB) - http://johnny.ihackstuff.com/ghdb.php
GHDB Tool from GNUCITIZEN - http://www.gnucitizen.org/ghdb
Goolag from cDC - http://www.goolag.org/download.html