exploit the possibilities

scip-dlink.txt

scip-dlink.txt
Posted Sep 8, 2008
Authored by Marc Ruef | Site scip.ch

The D-Link DIR-100 suffers from a long url filter evasion vulnerability.

tags | advisory
MD5 | 48ccd7532f8a2e18c0f2c36b21b1f0c9

scip-dlink.txt

Change Mirror Download
D-Link DIR-100 long url filter evasion

scip AG Vulnerability ID 3808 (09/08/2008)
http://www.scip.ch/cgi-bin/smss/showadvf.pl?id=3808

I. INTRODUCTION

D-Link DIR-100 is a small and cost-effective router and firewall device
for small offices and home users. More details are available at the
official product web site (German link):


http://www.dlink.de/?go=gNTyP9CgrdFOIC4AStFCF834mptYKO9ZTdvhLPG3yV3oV492gqltbNlwaaFp6DQoHDrpxC5H+40AAdvl

II. DESCRIPTION

Marc Ruef at scip AG found a possibility to evade url filters of the web
proxy to prevent access to web sites.

An attacker might add a very long string to the url to access web
resources althought their access is forbidden.

This problem could be verified in all firmware versions up to v1.12.

A similar vulnerability was already detected years ago in a similar
device Netgear RP114. [1, 2]

III. EXPLOITATION

It is possible to exploit the vulnerability with a common web browser by
using a long url (approx. 1'300 chars). You can expand the length of the
url by adding a non-used http get request parameter. Example url:

http://www.scip.ch/?foo=aaa(...)

A video illustrating this issue is available at the following url:

http://de.youtube.com/watch?v=WTzPn37XNl4

The Attack Tool Kit (ATK)[3] is able to exploit this vulnerability with
the following generic ASL code (expand the long URL request):

open|send GET http://www.scip.ch/?foo=aaa(...)
HTTP/1.0\n\n|sleep|close|pattern_not_exists *This URL is <font
color=red>blocked</font> by administrator !*

IV. IMPACT

With this vulnerability users are able to access forbidden web resources
without being filtered by the integrated web proxy service.

V. DETECTION

Detection of web based attacks requires a specialized web proxy and/or
intrusion detection system. Patterns for such a detection are available
and easy to implement.

VI. SOLUTION

We have informed D-Link on an early stage. Our technical requests were
not answered nor confirmed. Therefore, not official statement, patch or
upgrade is available.

We suggest the use of another device for filtering forbidden web
resources successfully.

VII. VENDOR RESPONSE

D-Link has been informed first via the unhandy web form at
http://www.dlink.com (no public mail address for such cases could be
found). The first responses claimed that the problem must be within a
wrong configuration setting. Further discussions were initiated.

The support was not able to understand the problem. Not even after
several step-by-step guides and examples. They always suggest I have to
upgrade to the latest firmware and they could not verify the problem.
Therefore, no official solution, workaround or patch is available.

VIII. SOURCES

scip AG - Security Consulting Information Process (german)
http://www.scip.ch/

scip AG Vulnerability Database (german)
http://www.scip.ch/cgi-bin/smss/showadvf.pl?id=3808

computec.ch document data base (german)
http://www.computec.ch/download.php

IX. DISCLOSURE TIMELINE

2008/07/25 Identification of the vulnerability by Marc Ruef
2008/07/28 First information to D-Link via web form
2008/07/28 First reply by D-Link support via support@service.dlink.biz
(ticket id 1375981)
2008/07/29 Providing our config for further analysis
2008/08/06 Request for actual status (no reply)
2008/08/29 Another request for actual status
2008/08/29 Response could not verify the problem
2008/09/01 Detailed explanation of the exploitation
2008/09/01 Responder could still not understand the problem
2008/09/08 Public disclosure of the advisory

X. CREDITS

The vulnerability was discovered by Marc Ruef.

Marc Ruef, scip AG, Zuerich, Switzerland
maru-at-scip.ch
http://www.scip.ch/

A1. BIBLIOGRAPHY

[1] http://www.securityfocus.com/bid/10404
[2] http://seclists.org/bugtraq/2004/May/0263.html
[3] http://www.computec.ch/projekte/atk/

A2. LEGAL NOTICES

Copyright (c) 2007-2008 scip AG, Switzerland.

Permission is granted for the re-distribution of this alert. It may not
be edited in any way without permission of scip AG.

The information in the advisory is believed to be accurate at the time
of publishing based on currently available information. There are no
warranties with regard to this information. Neither the author nor the
publisher accepts any liability for any direct, indirect or
consequential loss or damage from use of or reliance on this advisory.

Login or Register to add favorites

File Archive:

November 2020

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

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2020 Packet Storm. All rights reserved.

Services
Security Services
Hosting By
Rokasec
close