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4) Multiple Outdated Software Components
Multiple outdated software components containing vulnerabilities were found by the IoT Inspector.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: $IP/cgi-bin/ExportSettings.sh
Decryption:
OpenSSL 1.0.1: openssl enc -d -des-ede3-cbc -in -out -pass pass:himan OPENSSL 1.1.1: openssl enc -d -des-ede3-cbc -md md5 -in -out -pass pass:himan
Encryption:
OpenSSL 1.0.1: openssl enc -des-ede3-cbc -in -out -pass pass:himan OPENSSL 1.1.1: openssl enc -des-ede3-cbc -md md5 -in -out -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 $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: $IP/index.html Content-Type: application/x-www-form-urlencoded; charset=UTF-8 X-Requested-With: XMLHttpRequest Content-Length: 275 Connection: close isTest=true&notCallback=true&goformId=WAN_GATEWAYMODE_STATIC&static_wan_ipaddr=$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> ...
Multiple Outdated Software Components
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