Ubiquiti Networks EP-R6 / ER-X / ER-X-SFP Cross Site Scripting

Ubiquiti Networks EP-R6, ER-X, and ER-X-SFP with firmware version 1.9.1 suffer from a cross site scripting vulnerability.

MD5 | 9ea2bb02f107be6df0906b4c0a16edf9

SEC Consult Vulnerability Lab Security Advisory < 20170724-0 >
title: Cross-Site Scripting (XSS)
product: Ubiquiti Networks EP-R6, ER-X, ER-X-SFP
vulnerable version: Firmware v1.9.1
fixed version: Firmware v1.9.1.1
CVE number:
impact: Medium
homepage: https://www.ubnt.com
found: 2017-04-04
by: R. Freingruber, 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:
1) Reflected Cross Site Scripting (XSS) in Internet Explorer
This vulnerability can be exploited by deactivating or bypassing the
integrated XSS-filter of the Internet Explorer.

A reflected cross site scripting vulnerability was identified because of an
initialization error in "<IP>/files/index/". An attacker can exploit this
vulnerability by tricking a victim to visit a malicious website. The attacker
is able to hijack the session of the attacked user. If the user is currently
not logged in, the injected JavaScript code can start a bruteforce attack
(for example, with the default credentials ubnt:ubnt). After a session has
been established, the code has full control over the system via the CLI feature
which is basically a shell wrapper. By abusing this vulnerability an attacker
can open ports on the router or start a reverse shell.

Proof of concept:
1) Reflected Cross Site Scripting (XSS) in Internet Explorer
The following URL can be used as PoC:<svg><script>alert(1)<br>

The characters "=" and "/" are not allowed in this injection.
This restriction can be bypassed in Internet Explorer via the use
of a SVG and BR tag.
Since "/" is not allowed the <script> tag can't be closed and therefore
browsers will not execute the supplied code. Moreover, event handlers
(e.g. <svg onload=alert(1)>) can't be used because of the "=" restriction.
However, Internet Explorer can be tricked to parse the script via the use of
the SVG and BR tags.
It can be assumed that similar tricks exit for other browsers.

Vulnerable / tested versions:
EdgeRouter X SFP - Firmware v1.9.1

Vendor contact timeline:
2017-04-04: Contacting vendor through HackerOne. Vendor sets status to
2017-04-24: Asking for a update.
2017-04-25: Vendor responds that the fix is available in firmware
2017-05-05: Found the update on the website of the vendor. It was
available since 2017-04-28.
2017-05-15: Contacted vendor via e-mail and set the publication date
to 2017-07-24.
2017-07-24: Public release of security advisory

Upgrade to firmware v1.9.1.1 or later.


Advisory URL:


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EOF R. Freingruber, T. Weber / @2017

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