CHIYU IoT devices

Vulnerabilities found on IoT devices from CHIYU.

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

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:

HTTP response:

Proof-of-Concept: 02

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

HTTP request and response:

Proof-of-Concept: 03

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

HTTP request:

HTTP response

Proof-of-Concept: 04

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

HTTP request:

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:

Regarding CVE-2021-31251, it explains about the CHIYU serial converts & SEMAC door control panel has a security issue.

Because the telnet is able to connect with the device.

For this reason, CHIYU would like to include below the measures to fix the problem.

From now, all of the shipment has the latest firmware.

The firmware will close telnet.

if you want to upgrade your converter's firmware, please contact CHIYU for upgrading.

Checker and Exploit

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

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

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

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

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

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