Reviewing Code for Session Integrity issues - Revision history

Thomas Herlea: Added navigation to facilitate sequential reading online

2010-09-09T16:38:14Z

Added navigation to facilitate sequential reading online

2009-02-11T01:48:48Z

‎How to Locate the Potentially Vulnerable Code

2009-02-11T01:48:07Z

‎Introduction

2009-01-28T15:37:30Z

‎Displaying Data to user from Cookie

2009-01-28T14:48:58Z

‎Limiting Cookie Domain

2009-01-28T14:48:30Z

‎HTTP Only Cookie

2009-01-13T18:05:11Z

‎Leading Practice Patterns for Session Management/Integrity

2009-01-13T18:04:18Z

‎URL Rewriting

2009-01-13T18:04:00Z

‎HTML Hidden Field

2009-01-13T18:03:27Z

‎Displaying Data to user from Cookie

@@ Line 1: / Line 1: @@
-[[OWASP Code Review Guide Table of Contents]]__TOC__
+{{LinkBar
 ==Introduction==
 Cookies can be used to maintain a session state. This identifies a user whilst in the middle of using the application. Session IDs are a popular method of identifying a user. A "secure" session ID should be at least 128 bits in length and sufficiently random. Cookies can also be used to identify a user, but care must be taken in using cookies. Generally it is not recommended to implement a SSO (Single Sign On) solution using cookies; they were never intended for such use. Persistent cookies are stored on a user's hard disk and are valid depending on the expiry date defined in the cookie. The following are pointers when reviewing cookie related code.
@@ Line 66: / Line 72: @@
 http://msdn2.microsoft.com/en-us/library/ms533046.aspx <br />
 http://java.sun.com/j2ee/sdk_1.3/techdocs/api/javax/servlet/http/Cookie.html
 [[Category:OWASP Code Review Project]]
 [[Category:Session Management]]

@@ Line 4: / Line 4: @@
 ==How to Locate the Potentially Vulnerable Code==
-If the cookie object is being set with various attributes apart from the session ID check the cookie is set only to transmit over HTTPS/SSL. In Java this is performed by the method:
+If the cookie object is being set with various attributes apart from the session ID, check that the cookie is set only to transmit over HTTPS/SSL. In Java this is performed by the method:
   cookie.setSecure() (Java)

@@ Line 1: / Line 1: @@
 [[OWASP Code Review Guide Table of Contents]]__TOC__
 ==Introduction==
-Cookies can be used to maintain a session state. This identifies a user whilst in the middle of using the application. Session IDs are a popular method of identifying a user. A "secure" session ID should be at least 128 bits in length and sufficiently random. Cookies can also be used to identify a user, but care must be taken in using cookies. Generally it is not recommended to implement a SSO (Single Sign on) solution using cookies; they were never intended for such use. Persistent cookies are stored on a user hard disk and are valid depending on the expiry date defined in the cookie. The following are pointers when reviewing cookie related code.
+Cookies can be used to maintain a session state. This identifies a user whilst in the middle of using the application. Session IDs are a popular method of identifying a user. A "secure" session ID should be at least 128 bits in length and sufficiently random. Cookies can also be used to identify a user, but care must be taken in using cookies. Generally it is not recommended to implement a SSO (Single Sign On) solution using cookies; they were never intended for such use. Persistent cookies are stored on a user's hard disk and are valid depending on the expiry date defined in the cookie. The following are pointers when reviewing cookie related code.
 ==How to Locate the Potentially Vulnerable Code==

@@ Line 27: / Line 27: @@
 During the review, if the cookie is assigned to more than one domain, make note of it and query why this is the case.
-===Displaying Data to user from Cookie===
+===Displaying Data to User from Cookie===
 Make sure that data being displayed to a user from a cookie is HTML encoded. This mitigates some forms of Cross Site Scripting.

@@ Line 25: / Line 25: @@
   Response.Cookies("domain").Domain = "support.example.com" (Classic ASP)
-During the review, if the cookie is assigned to more than one domain make note of it and query why this is the case.
+During the review, if the cookie is assigned to more than one domain, make note of it and query why this is the case.
 ===Displaying Data to user from Cookie===

@@ Line 15: / Line 15: @@
   cookie.HttpOnly = true (C#)
-Here cookie should only be accessible via ASP.NET.
+Here the cookie should only be accessible via ASP.NET.
 Note that HTTPOnly property is not supported in Classic ASP pages.

@@ Line 52: / Line 52: @@
 '''Valid Session checking''':
 Upon any HTTP request the framework should check if the user pertaining to the HTTP request (via session ID) is valid.
 '''Successful Authentication''':
-Upon a successful login the user should be issued a new session identifier. The old session ID should be invalidated. This prevents session fixation attacks and the same browser also sharing the same session ID in a multi user environment. Some times the session ID is per browser and the session remains valid while the browser is alive.
+Upon a successful login the user should be issued a new session identifier. The old session ID should be invalidated. This prevents session fixation attacks and the same browser also sharing the same session ID in a multi user environment. Sometimes the session ID is per browser, and the session remains valid while the browser is alive.
 '''Logout''':
-This also leads to the idea of why a logout button is so important. The logout button should invalidate the users session ID when it is selected.
+This also leads to the idea of why a logout button is so important. The logout button should invalidate the user’s session ID when it is selected.
 ==Related Articles==

@@ Line 42: / Line 42: @@
 === URL Rewriting ===
-URL rewriting approaches session tracking by appending a unique id pertaining to the user at the end of the URL.
+URL rewriting approaches session tracking by appending a unique ID pertaining to the user at the end of the URL.
   <A HREF="/smackmenow.htm?user=User001928394857738000094857hfduekjkksowie039848jej393">Click Here</A>
 ==Leading Practice Patterns for Session Management/Integrity==

@@ Line 35: / Line 35: @@
 ==Session Tracking/Management Techniques==
 === HTML Hidden Field ===
-The HTML Hidden field could be used to perform session tracking. Upon each HTTP POST request the hidden field is passed to the server identifying the user. It would be in the form of
+The HTML Hidden field could be used to perform session tracking. Upon each HTTP POST request, the hidden field is passed to the server identifying the user. It would be in the form of
   <INPUT TYPE="hidden" NAME="user"VALUE="User001928394857738000094857hfduekjkksowie039848jej393">
 Server-side code is used to perform validation on the VALUE in order to ensure the used is valid. This approach can only be used for POST/Form requests.