CommScope Ruckus IoT Controller 1.7.1.0 Undocumented Account Vulnerability

1. Vulnerability Details

     Affected Vendor: CommScope
     Affected Product: Ruckus IoT Controller
     Affected Version: 1.7.1.0 and earlier
     Platform: Linux
     CWE Classification: CWE-798: Use of Hard-coded Credentials, CWE-912: Hidden Functionality
     CVE ID: CVE-2021-33216


2. Vulnerability Description

     An upgrade account is included in the IoT Controller OVA that
     provides the vendor undocumented access via Secure Copy (SCP).


3. Technical Description

     Once the OVA is imported into VirtualBox, a VMDK file is
     created. The VMDK file can be mounted and the directory
     structure and its contents can be perused.

     An authorized_keys file exists that allows an
     individual/organization possessing the SSH private key to
     access the virtual appliance using the 'vriotiotupgrade'
     account. The 'vriotiotupgrade' account is restricted to scp,
     per the rssh configuration.

     Additionally, it appears that the IoT Controller has rssh version 2.3.4
     installed and in use. At the time of this advisory, there are at least
     three remote command injection vulnerabilities in this particular version
     of rssh: CVE-2019-3463, CVE-2019-3464 and CVE-2019-1000018.


4. Mitigation and Remediation Recommendation

     The vendor has released an updated firmware (1.8.0.0) which
     remediates the described vulnerability. Firmware and release
     notes are available at:

     https://www.commscope.com/globalassets/digizuite/917216-faq-security-advisory-id-20210525-v1-0.pdf


5. Credit

     This vulnerability was discovered by Jim Becher (@jimbecher)
     of KoreLogic, Inc.


6. Disclosure Timeline

     2021.03.30 - KoreLogic submits vulnerability details to
                  CommScope.
     2021.03.30 - CommScope acknowledges receipt and the intention
                  to investigate.
     2021.04.06 - CommScope notifies KoreLogic that this issue,
                  along with several others reported by KoreLogic,
                  will require more than the standard 45 business
                  day remediation timeline.
     2021.04.06 - KoreLogic agrees to extend disclosure embargo if
                  necessary.
     2021.04.30 - CommScope informs KoreLogic that remediation for
                  this vulnerability will be available inside of the
                  standard 45 business day timeline. Requests
                  KoreLogic acquire CVE number for this
                  vulnerability.
     2021.05.14 - 30 business days have elapsed since the
                  vulnerability was reported to CommScope.
     2021.05.17 - CommScope notifies KoreLogic that the patched
                  version of the firmware will be available the week
                  of 2021.05.24.
     2021.05.19 - KoreLogic requests CVE from MITRE.
     2021.05.19 - MITRE issues CVE-2021-33216.
     2021.05.25 - CommScope releases firmware 1.8.0.0 and associated
                  advisory.
     2021.05.26 - KoreLogic public disclosure.


7. Proof of Concept

     With the VMDK file mounted at the current working directory:
     $ find . -name authorized_keys
     ./VRIOT/ap-images/authorized_keys
     ./VRIOT/ops/ap-images/authorized_keys

     $ cat VRIOT/ap-images/authorized_keys
     ssh-rsa
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
[email protected]

     $ cat VRIOT/ops/ap-images/authorized_keys
     ssh-rsa
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
[email protected]

     $ grep "ap-images" etc/passwd
     vriotiotupgrade:x:1002:1002::/VRIOT/ap-images/:/usr/bin/rssh

     $ tail -8 etc/ssh/sshd_config
     Match User vriotiotupgrade
         PasswordAuthentication no
         AuthorizedKeysFile     /VRIOT/ap-images/authorized_keys

     Match User vriotha
     PasswordAuthentication yes

     $ grep -v ^# etc/rssh.conf
     logfacility = LOG_USER
     allowscp
     umask = 022