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Web Application Penetration Testing
• Remove any unnecessary comments (copyrights, bug
information, specific framework comments)
• Remove META and generator tags
• Use the companies own css or js files and do not store those in a
framework-specific folders
• Do not use default scripts on the page or obfuscate them if they
must be used.
Specific files and folders
General guidelines:
• Remove any unnecessary or unused files on the server. This
implies text files disclosing information about versions and
installation too.
• Restrict access to other files in order to achieve 404-response
when accessing them from outside. This can be done, for
example, by modifying htaccess file and adding RewriteCond
or RewriteRule there. An example of such restriction for two
common WordPress folders is presented below.
RewriteCond %{REQUEST_URI} /wp-login\.php$ [OR]
RewriteCond %{REQUEST_URI} /wp-admin/$
RewriteRule $ /http:/your_website [R=404,L]
However, these are not the only ways to restrict access. In order to
automate this process, certain framework-specific plugins exist.
One example for WordPress is StealthLogin (http: /wordpress.org/
plugins/stealth-login-page).
Additional approaches
General guidelines:
[1] Checksum management
The purpose of this approach is to beat checksum-based scanners
and not let them disclose files by their hashes. Generally, there are
two approaches in checksum management:
• Change the location of where those files are placed (i.e. move
them to another folder, or rename the existing folder)
• Modify the contents - even slight modification results in a
completely different hash sum, so adding a single byte in the end
of the file should not be a big problem.
[2] Controlled chaos
A funny and effective method that involves adding bogus files and
folders from other frameworks in order to fool scanners and confuse
an attacker. But be careful not to overwrite existing files and
folders and to break the current framework!
Fingerprint Web Application
(OTG-INFO-009)
Summary
There is nothing new under the sun, and nearly every web application
that one may think of developing has already been developed.
With the vast number of free and open source software projects
that are actively developed and deployed around the world, it is
very likely that an application security test will face a target site
that is entirely or partly dependent on these well known applications
(e.g. Wordpress, phpBB, Mediawiki, etc). Knowing the web
application components that are being tested significantly helps
in the testing process and will also drastically reduce the effort
required during the test. These well known web applications have
known HTML headers, cookies, and directory structures that can
be enumerated to identify the application.
Test Objectives
Identify the web application and version to determine known vulnerabilities
and the appropriate exploits to use during testing.
How to Test
Cookies
A relatively reliable way to identify a web application is by the application-specific
cookies.
Consider the following HTTP-request:
GET / HTTP/1.1
User-Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:31.0)
Gecko/20100101 Firefox/31.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
‘’’Cookie: wp-settings-time-1=1406093286; wp-settingstime-2=1405988284’’’
DNT: 1
Connection: keep-alive
Host: blog.owasp.org
The cookie CAKEPHP has automatically been set, which gives information
about the framework being used. List of common cookies
names is presented in Cpmmon Application Identifiers section.
However, it is possible to change the name of the cookie.
HTML source code
This technique is based on finding certain patterns in the HTML
page source code. Often one can find a lot of information which
helps a tester to recognize a specific web application. One of the
common markers are HTML comments that directly lead to application
disclosure. More often certain application-specific paths
can be found, i.e. links to application-specific css and/or js folders.
Finally, specific script variables might also point to a certain application.
From the meta tag below, one can easily learn the application
used by a website and its version. The comment, specific paths
and script variables can all help an attacker to quickly determine
an instance of an application.
More frequently such information is placed between tags, in tags or at the end of the page. Neverthe-