what you don't know can hurt you
Home Files News &[SERVICES_TAB]About Contact Add New

.NET Cross Site Scripting

.NET Cross Site Scripting
Posted Aug 30, 2012
Authored by Zamir Paltiel

A vulnerability in the .Net Request Validation mechanism allows bypassing the filter and execution of malicious scripts in the browsers of users via cross site scripting attacks. The exploitation technique explained here allows sending tags through the Request Validation Filter in a manner that will pass browser syntax and be rendered by browsers.

tags | exploit, xss
SHA-256 | 2e4ce4802fcc15ab4ea201c0086a4407e49cf77f81bc189e1205c8e38bb63357

.NET Cross Site Scripting

Change Mirror Download

.Net Cross Site Scripting - Request Validation Bypassing
==========================================
Seeker Research Center
By Zamir Paltiel, August 2012

Overview
========
A vulnerability in the .Net Request Validation mechanism allows bypassing the filter and execution of malicious scripts in the browsers of users via Cross Site Scripting attacks.
The exploitation technique explained here allows sending tags through the Request Validation Filter in a manner that will pass browser syntax and be rendered by browsers.

Details
========
The .Net Request Validation mechanism prevents attackers from sending tags as the value of the parameters. It is however possible to bypass this mechanism and send arbitrary tags that facilitate script execution.
This is caused by the fact that although <tag> is restricted by the Request Validation filter, <%tag> is not restricted but parsed by Internet Explorer browsers as a valid tag.

Exploit
=======
An example of the exploitation of this vulnerability would be crafting a link to a page that reflects a parameter value to the user.
As the value of the parameter the attacker would provide a <%tag> with the style attribute and an expression, for example: http://www.vulnerablesite.com/login.aspx?param=<%tag style="xss:expression(alert(123))" >
This will bypass the filter and execute the script in the brackets.

Affected Systems
================
This vulnerability has been tested on .Net frameworks 2.0 and above.

Vendor Response
===============
“The Request Validation Feature in ASP.NET is designed to perform basic input validation.  It is not designed to make security decisions for applications developed using ASP.NET.  Only the original developers can determine what content the ASP.NET application is designed to process and handle.  Microsoft recommends that all software developers perform input/data validation of all sources.  We do this to encourage our customers to make more robust applications that are less susceptible to security issues.  The Request Validation Feature was designed and released to help developers in this effort.  For more information about our recommendations to software developers, please see the following MSDN article:
http://msdn.microsoft.com/en-us/library/ff649487.aspx#pagguidelines0001_inputdatavalidation.”
Microsoft therefore will not be releasing a fix for this issue.

Credit
======
This vulnerability has been identified by Zamir Paltiel, Seeker Research Center.
For more information please visit http://www.quotium.com/prod/ResearchCenter/XSS-NetrequestValidation.php


Login or Register to add favorites

File Archive:

June 2022

  • Su
  • Mo
  • Tu
  • We
  • Th
  • Fr
  • Sa
  • 1
    Jun 1st
    19 Files
  • 2
    Jun 2nd
    16 Files
  • 3
    Jun 3rd
    28 Files
  • 4
    Jun 4th
    0 Files
  • 5
    Jun 5th
    0 Files
  • 6
    Jun 6th
    19 Files
  • 7
    Jun 7th
    23 Files
  • 8
    Jun 8th
    11 Files
  • 9
    Jun 9th
    10 Files
  • 10
    Jun 10th
    4 Files
  • 11
    Jun 11th
    0 Files
  • 12
    Jun 12th
    0 Files
  • 13
    Jun 13th
    0 Files
  • 14
    Jun 14th
    0 Files
  • 15
    Jun 15th
    0 Files
  • 16
    Jun 16th
    0 Files
  • 17
    Jun 17th
    0 Files
  • 18
    Jun 18th
    0 Files
  • 19
    Jun 19th
    27 Files
  • 20
    Jun 20th
    65 Files
  • 21
    Jun 21st
    10 Files
  • 22
    Jun 22nd
    8 Files
  • 23
    Jun 23rd
    6 Files
  • 24
    Jun 24th
    6 Files
  • 25
    Jun 25th
    0 Files
  • 26
    Jun 26th
    0 Files
  • 27
    Jun 27th
    15 Files
  • 28
    Jun 28th
    14 Files
  • 29
    Jun 29th
    0 Files
  • 30
    Jun 30th
    0 Files

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2022 Packet Storm. All rights reserved.

Hosting By
Rokasec
close