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Difference between revisions of "Testing for Bypassing Authentication Schema (OTG-AUTHN-004)"

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(Bypassing authentication schema methods)
(Bypassing authentication schema methods)
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'''Session Issues'''
 
'''Session Issues'''
 
* Session ID Prediction
 
* Session ID Prediction
 +
Many web applications manage authentication using session identification values(SESSION ID). Therefore if Session ID generation is predictable a malicious user could be able to find a valid session ID and gain unauthorized access to the application, impersonating  a previously authenticated user.
  
 
[[Image:basm-sessid.jpg]]
 
[[Image:basm-sessid.jpg]]
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[[Image:basm-sessid2.jpg]]
 
[[Image:basm-sessid2.jpg]]
  
* Session Fixation
 
  
 
'''Sql Injection (HTML Form Authentication)'''
 
'''Sql Injection (HTML Form Authentication)'''

Revision as of 15:03, 11 November 2006

OWASP Testing Guide v2 Table of Contents

Brief Summary


While most most application require authentication for gaining access to private information or tasks, not every authentication method is able to provide adequate security level.

Negligence, ignorance or simple understatement of the security threats often result in authentication schemes that can be easily bypassed by simply skipping the login page and directly calling an internal page that is supposed to be accessed only after authentication has been performed.

In addition to this it is often possible to bypass compulsory authentication tampering with requests and tricking the application into thinking that we're already authenticated either by modifying the given URL parameter or by manipulating form or by counterfeiting sessions.

Description of the Issue


Problems related to Authentication Schema could be found at different stages of software development life cycle (SDLC), like design, development and deployment phase.

Examples of design errors include a wrong definition of application parts to be protected, the choice of not applying strong encryption protocols for securing authentication data exchange, and many more.

Problems in development phase are for example the incorrect implementation of input validation functionalities, or not following the security best practices for the specific language.

In addition there are issues during application setup (Installation and configuration activities) due to a lack in required technical skills, or due to poor documentation available.


Black Box testing and example

There are several methods to bypass the authentication schema in use by a web application:

  • Direct page request
  • Parameter Modification
  • Session ID Prediction
  • Session Fixation
  • Sql Injection


Bypassing authentication schema methods

Direct page request

Several web applications implement access control only inside the login page, otherwise if a user requests directly a different page in the designed protected area, the authentication schema could be bypassed.

Basm-directreq.jpg


Parameter Modification


Another problem related to authentication design is to let the application verify a succesful login upon fixed value parameters.

Therefore a user could modify these parameters to gain access to the protected areas without providing valid credentials.

http://www.site.com/page.asp?authenticated=no 
[email protected] /home $nc www.site.com 80                    
GET /page.asp?authenticated=yes HTTP/1.0                    
                                                            
HTTP/1.1 200 OK                                             
Date: Sat, 11 Nov 2006 10:22:44 GMT                         
Server: Apache                                              
Connection: close                                           
Content-Type: text/html; charset=iso-8859-1                 
                                                            
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">          
<HTML><HEAD>                                                
</HEAD><BODY>                                               
<H1>You Are Auhtenticated</H1>                              
</BODY></HTML>

Basm-parammod.jpg


Session Issues

  • Session ID Prediction

Many web applications manage authentication using session identification values(SESSION ID). Therefore if Session ID generation is predictable a malicious user could be able to find a valid session ID and gain unauthorized access to the application, impersonating a previously authenticated user.

Basm-sessid.jpg

Basm-sessid2.jpg


Sql Injection (HTML Form Authentication)


Basm-sqlinj.jpg

Basm-sqlinj2.gif


Gray Box testing and example

Testing for Topic X vulnerabilities:
...
Result Expected:
...

References

Whitepapers
...
Tools
...


OWASP Testing Guide v2

Here is the OWASP Testing Guide v2 Table of Contents OWASP Testing Guide v2 Table of Contents

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