Secunia Research: Opera Browser Page Redirection Cross-Site Scripting Vulnerability

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                   Secunia Research 26/02/2003

              - Opera browser Cross Site Scripting -

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Table of Contents

1..........................................................Description
2....................................................Affected Software
3.............................................................Severity
4..............................................................Exploit
5.............................................................Solution
6...........................................................Time Table
7........................................................About Secunia
8..............................................................Credits
9.........................................................Verification

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1) Description

A vulnerability exists in the way the Opera browser generates a
temporary page for displaying a redirection, when "Automatic
redirection" is disabled (not default setting).

When Opera generates a page for displaying a redirect, it does not
strip any characters, making it possible to inject malicious script
code into the page generated by the Opera browser. This page has the
same privileges as the domain trying to redirect the user, making it
possible to steal cookies, hi-jack sessions etc. from the domain.

Eg. many websites use a "redirect-script" to redirect users. These 
scripts often take arguments without any further validation, because
their only function is to send the user to a new URL. However, when
Opera is set to not automatically redirect a user, Opera will display
this URL on a temporary page without stripping it for malicious code.

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2) Affected Software

Following have been tested and found vulnerable:
Opera prior to 7.02 on Windows
Opera 6.x on Linux

Vendor:
http://www.opera.com/

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3) Severity

Rating:  Less critical
Impact:  Cross Site Scripting
Where:   From Remote

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4) Exploit

Sample exploit:
http://www.secunia.com/secunia_research/2003-1/exploit/

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5) Solution

Vendor patch:
Windows: Update to latest version. Opera v7.02 is not vulnerable.
Linux: No update available.

Workaround:
A workaround would be to leave "Automatic redirection" enabled.

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6) Time Table

15/02/2003 - Vulnerability discovered
16/02/2003 - Further research
17/02/2003 - Vendor informed
19/02/2003 - Vendor confirmed and fixed vulnerability
26/02/2003 - Vendor released Opera v7.02
26/02/2003 - Public disclosure of vulnerability

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7) About Secunia

Secunia collects, validates, assesses and writes advisories regarding
all the latest software vulnerabilities disclosed to the public. These
advisories are gathered in a publicly available database at the
Secunia website: 

http://www.secunia.com/

Secunia offers services to our customers enabling them to receive all
relevant vulnerability information to their specific system
configuration.

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8) Credits

Jakob Balle, Secunia

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9) Verification

Please verify this advisory by visiting the Secunia website.

http://www.secunia.com/secunia_research/2003-1/

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