Difference between revisions of "Codereview-Authorization"

Revision as of 15:24, 1 July 2008

Introduction

Authorisation is key in multiuser environments where user data should be segregated. different clients/users should not see other clients data (Horizontal authorisation). Authorisation can also be used to restrict functionality to a subset of users. "super users" would have extra admin functionality a "regular user" would not have access to (Vertical authorisation).

Authorisation is a very bespoke area in application development. It can be implemented via a lookup table in a users session which is loaded upon sucessful authentication. It coule be a realtime interrogation of a backend LDAP or database system upon each request.

Good Example

Check authorisation upon every user request.

String action = request.getParameter("action")
if (action == "doStuff"){
  boolean permit = session.authTable.isAuthorised(action); // check table if authoirsed to do action
}
if (permit){
 doStuff();
}else{
 throw new (InvalidRequestException("Unauthorised request"); // inform user of no authorisation
 session.invalidate(); // Kill session
}

Bad Example

Building the GUI based on the users authorisation. "If he cant see the control we wont be able to use it" 

- Common enough error. If a user has the URL the functionality can still be called. This is due to no authorisation check being perfromed upon every HTTP request.

Related Vulnerabilities

• Reviewing Code for OS Injection

Operating system injection can be used to totally ignore authorisation constraints.

• Reviewing Code for SQL Injection

SQL injection can be used to circumvent authorisation

• Reviewing Code for Data Validation

The root of all evil

• Reviewing Code for Error Handling

• Reviewing The Secure Code Environment

Insecure class files, folders in deployment may be used to attack an application outside the actual application itself.

• Reviewing Code for Authorization Issues

• Reviewing Code for Session Integrity issues

• Reviewing Code for Race Conditions