exploit the possibilities

ZTE Mobile Hotspot MS910S Backdoor / Hardcoded Password

ZTE Mobile Hotspot MS910S Backdoor / Hardcoded Password
Posted Aug 27, 2020
Authored by T. Weber | Site sec-consult.com

ZTE Mobile Hotspot MS910S version DL_MF910S_CN_EUV1.00.01 suffers from having a hard-coded administrative password, busybox vulnerabilities, and having a known backdoor in the GoAhead webserver.

tags | exploit, vulnerability
advisories | CVE-2019-3422
MD5 | 5fee15e2fe67f4a312641b206b87d209

ZTE Mobile Hotspot MS910S Backdoor / Hardcoded Password

Change Mirror Download
SEC Consult Vulnerability Lab Security Advisory < 20200827-0 >
=======================================================================
title: Multiple Vulnerabilities
product: ZTE mobile Hotspot MS910S
vulnerable version: DL_MF910S_CN_EUV1.00.01
fixed version: -
CVE number: CVE-2019-3422
impact: High
homepage: https://www.zte.com.cn
found: 2019-09-25
by: Ying Shen
T. Weber (Office Vienna)
SEC Consult Vulnerability Lab

An integrated part of SEC Consult
Europe | Asia | North America

https://www.sec-consult.com

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

Vendor description:
-------------------
"ZTE Corporation is a global leader in telecommunications and information
technology. Founded in 1985 and listed on both the Hong Kong and Shenzhen Stock
Exchanges, the company has been committed to providing integrated end-to-end
innovations to deliver excellence and value to consumers, carriers, businesses
and public sector customers from over 160 countries around the world to enable
increased connectivity and productivity."

Source: https://www.zte.com.cn/global/about/corporate_information


Business recommendation:
------------------------
The vendor recommends to change the hardware and use a newer product.

SEC Consult recommends to remove the device from productive environments.


Vulnerability overview/description:
-----------------------------------
1) Hard-coded Administrator Password
The hard-coded administrator password was found in the ZTE mobile hotspot
MS910S firmware version "CN_EUV1.00.01", which is available at.
http://devicedownload.zte.com.cn/support/product/201701161506340/soft/20170116151106465.zip

2) Known BusyBox Vulnerabilities
The used BusyBox toolkit in version 1.15.0 is outdated and contains multiple
known vulnerabilities. The outdated version was found by IoT Inspector.
One of the discovered vulnerabilities (CVE-2017-16544) was verified by using
the MEDUSA scalable firmware run-time.

3) Known Backdoor in GoAhead Webserver
An unusual "telnetd" port was identified on an emulated device which led to the
assumption that a backdoor can be opened via the GoAhead web-server.
This conclusion was done because of a blog post from another researcher:
http://blog.asiantuntijakaveri.fi/2017/03/backdoor-and-root-shell-on-zte-mf286.html

By partially reverse engineering the binaries of the GoAhead webserver, the
functionality described in the corresponding blog post can be underpinned.

Proof of concept:
-----------------
1) Hard-coded Administrator Password
The firmware file (ZTE_MF910SV1.0.1B09.bin) is using the JFFS2 filesystem which
was extracted. The hardcoded password can be found in the /etc/shadow file
within the firmware:

/_DL_MF910S_CN_EUV1.00.01.exe.extracted/Data/version/_ZTE_MF910SV1.0.1B09.bin.extracted/jffs2-root/fs_1/etc/shadow

The file content is shown below:
-------------------------------------------------------------------------------
root:$1$$zdlNHiCDxYDfeF4MZL.H3/:10933:0:99999:7:::
Admin:$1$$zdlNHiCDxYDfeF4MZL.H3/:10933:0:99999:7:::
bin::10933:0:99999:7:::
daemon::10933:0:99999:7:::
adm::10933:0:99999:7:::
lp:*:10933:0:99999:7:::
sync:*:10933:0:99999:7:::
shutdown:*:10933:0:99999:7:::
halt:*:10933:0:99999:7:::
uucp:*:10933:0:99999:7:::
operator:*:10933:0:99999:7:::
nobody::10933:0:99999:7:::
ap71::10933:0:99999:7:::
-------------------------------------------------------------------------------
Both the user "root" and "admin" are using the same weak hardcoded password
"5up".

2) Known BusyBox Vulnerabilities
BusyBox version 1.12.0 contains multiple CVEs like:
CVE-2013-1813, CVE-2016-2148, CVE-2016-6301, CVE-2011-2716, CVE-2011-5325,
CVE-2015-9261, CVE-2016-2147 and more.

The BusyBox shell autocompletion vulnerability (CVE-2017-16544) was verified on
an emulated device. A file with the name "\ectest\n\e]55;test.txt\a" was crea-
ted to trigger the vulnerability.

-------------------------------------------------------------------------------
# ls "pressing <TAB>"
test
]55;test.txt
#
-------------------------------------------------------------------------------

3) Known Backdoor in GoAhead Webserver
Starting the telnet daemon on the emulated device leads to a listener on a very
unusual port:
[...]
# telnetd
#netstat -tulen
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:4719 0.0.0.0:* LISTEN
[...]

Because this seems to be not configured on the system by any file, the BusyBox
binary was inspected.

The pseudocode snippet of BusyBox' telnetd function that was generated by Hex-
Rays ARM Decompiler, indicated that this port was hard-coded:
<snip>
dword_788DC = (int)"/bin/login";
dword_788E0 = (int)"/etc/issue.net";
v3 = sub_5DBFC(a2, "f:l:Kip:b:F", &dword_788E0, &dword_788DC, &v76, &v75);
v4 = v3 & 8;
v5 = v3;
if ( !(v3 & 8) && !(v3 & 0x40) )
sub_64A10(v3 & 8);
if ( (v5 & 0x48) != 64 )
{
openlog((const char *)dword_798DC, 1, 24);
dword_78630 = 2;
}
if ( v5 & 0x10 )
v6 = sub_64FF8(v76);
else
v6 = 4719; <------------------------------------- Port "4719"
if ( !v4 )
{
v2 = sub_65578(v75, v6);
sub_E394(v2, 1);
sub_D9B0(v2);
goto LABEL_13;
}
dword_788D8 = (int)sub_1C480(0);
if ( dword_788D8 )
{
<snip>

This led to the assumption that the GoAhead webserver was modified like
described in the following blog post:
http://blog.asiantuntijakaveri.fi/2017/03/backdoor-and-root-shell-on-zte-mf286.html

Inspecting the GoAhead webserver binary reinforces this assumption. The
pseudocode was generated with Hex-Rays ARM Decompiler, like for the prior
BusyBox binary:
<snip>
int __fastcall sub_21D48(int a1)
{
int v1; // r5
const char *v2; // r4

v1 = a1;
cfg_get("debug_level");
v2 = (const char *)sub_17DF0(v1, "change_mode", "");
cfg_set("login_9527", "1");
if ( !strcmp("1", v2) )
{
cfg_set("change_mode", "1");
cfg_get("debug_level");
system("mode_change 1");
}
else if ( !strcmp("2", v2) ) <--- change mode "2"
{
cfg_get("debug_level");
system("telnetd &"); <--------- telnet daemon started
}
else if ( !strcmp("3", v2) )
{
cfg_get("debug_level");
system("rem_start.sh &");
}
else if ( !strcmp("4", v2) )
{
cfg_get("debug_level");
system("rem_kill.sh &");
}
else
{
cfg_set("change_mode", "0");
cfg_get("debug_level");
system("mode_change 0");
}
return sub_34374(v1, "success");
}
<snip>

Other scripts could also be started via the webserver, like "rem_start.sh".
This script contains the following lines:

#!/bin/sh
if ps|grep remserial
then
echo "remserial is running.."
else
remserial -p 10005 -r 192.168.1.10 -s "115200 raw" /dev/ttyUSB0 &
fi

That means, that a serial console with the speed of 115200 Baud on port 10005
is started.

Vulnerable / tested versions:
-----------------------------
The following firmware has been tested, which was the latest version available
during the time of the test:
* DL_MF910S_CN_EUV1.00.01


Vendor contact timeline:
------------------------
2019-09-30: Contacting vendor through psirt@zte.com.cn
2019-10-10: Vendor provides initial contact.
2019-10-14: Vendor confirmed receive of the advisory.
2019-10-15: ZTE confirmed the hard-coded administrator password issue. The
GoAhead webserver backdoor is still analyzed.
2019-11-05: ZTE released a Security Bullentin that the product MF910S is
end-of-service*. SEC Consult Vulnerability Lab added a grace
time of 9 months so that the hardware can be changed.
2020-08-27: Release of security advisory.

* http://support.zte.com.cn/support/news/LoopholeInfoDetail.aspx?newsId=1011722


Solution:
---------
Upgrade to new hardware.


Workaround:
-----------
None.


Advisory URL:
-------------
https://www.sec-consult.com/en/vulnerability-lab/advisories/index.html


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

SEC Consult Vulnerability Lab

SEC Consult
Europe | Asia | North America

About SEC Consult Vulnerability Lab
The SEC Consult Vulnerability Lab is an integrated part of SEC Consult. It
ensures the continued knowledge gain of SEC Consult in the field of network
and application security to stay ahead of the attacker. The SEC Consult
Vulnerability Lab supports high-quality penetration testing and the evaluation
of new offensive and defensive technologies for our customers. Hence our
customers obtain the most current information about vulnerabilities and valid
recommendation about the risk profile of new technologies.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Interested to work with the experts of SEC Consult?
Send us your application https://www.sec-consult.com/en/career/index.html

Interested in improving your cyber security with the experts of SEC Consult?
Contact our local offices https://www.sec-consult.com/en/contact/index.html
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Mail: research at sec-consult dot com
Web: https://www.sec-consult.com
Blog: http://blog.sec-consult.com
Twitter: https://twitter.com/sec_consult

EOF Thomas Weber / @2020


Login or Register to add favorites

File Archive:

September 2021

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