lundi, février 20 2012

Security of Smart Meters

There have been some contreverse lately about the (in-) security of Smart Meters. It started with the talk “Smart Hacking for Privacy” at 28c3 over Christmas and New Year:

While some articles about the 28c3 talk were quite acruate and neutral, others were a little more sensionalists and probably generalised the topic a little too quickly.

As a happy owner of such a smart meter in the context of a study, I wanted to have a closer look at the security of my installation. As mentioned in the previously linked article, there is as far as I’m aware no direct data connection back to the EWZ on the occasion of this study. Data is kept for a few weeks on the smart meter and retrieved by the Android tablet and stored on this device. This is also the reason why I must start the Android tablet at least every couple of weeks, ensuring that no data gets lost.

So no Internet connection in our EWZ study – and therefore a lot less potential problems Clignement d'œil. Let’s have a look how the data transfer between the smart meter and the tablet is done.

The first communication between the smart meter and the flat is done using a Devolo device over the electric wiring. I’m not aware of any special security problem for this technology, so let’s assume for now we’re safe there.

Once in the flat, the information transits via a second Devolo device which sends the feed to the Android tablet over WiFi. A closer look about the used settings (on Windows, run netsh wlan show all in a console) shows that they are pretty safe as WPA2 is in use:

Network type            : Infrastructure
    Authentication          : WPA2-Personal
    Encryption              : CCMP
BSSID 1                 : [BSS_MAC_ADDRESS]
Signal             : 99%
Radio type         : 802.11n
Channel            : 2
Basic rates (Mbps) : 1 2 5.5 11
Other rates (Mbps) : 6 9 12 18 24 36 48 54

But is there even a way to snoop some of the traffic and get a better understanding of this solution? Having your neighbour cracking the WPA2 password of the Devolo is possible, but I tend to disconnect it once I’m done with the tablet anyway – another layer of security to bypass for an attacker wanting to “hack” my smart meter.

The key – as a local curious person – to gain access to the network traffic is to exploit one of the three ethernet connectors of the Devolo device which also serves as WiFi Access Point. The network traffic shown below is therefore only accessible to local attackers which either have access to the AP, the smart meter or maybe via the electrical wire.

In a standard usage, we see a broadcast on a low network level of 50 bytes of data every 2 seconds. This matches exactly the immediate consumption update the tablet gets:


The data field therefore certainly contains the measurement, which is readable by anyone which can see the broadcast. But as said before, this is limited to local attackers (unless flaws exist in the Devolo devices which I don’t know about).

When shuting down the tablet and restarting it, we get a more interesting capture were we have what seems to be a fixed IP address looking for


Filtering all the captured traffic for only ARP requests show that the Android device tries to successively find:



    A ping confirms that addresses & are valid IP addresses in this configuration, but that seems either way slower or further away than

    Pinging with 32 bytes of data:
    Reply from bytes=32 time=4ms TTL=64
    Reply from bytes=32 time=1ms TTL=64
    Reply from bytes=32 time=1ms TTL=64
    Reply from bytes=32 time=1ms TTL=64
    Ping statistics for
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
    Approximate round trip times in milli-seconds:
    Minimum = 1ms, Maximum = 4ms, Average = 1ms
    Pinging with 32 bytes of data:
    Reply from bytes=32 time=17ms TTL=255
    Reply from bytes=32 time=11ms TTL=255
    Reply from bytes=32 time=7ms TTL=255
    Reply from bytes=32 time=7ms TTL=255
    Ping statistics for
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
    Approximate round trip times in milli-seconds:
        Minimum = 7ms, Maximum = 17ms, Average = 10ms

    The suspicion that is the Smart Meter itself turns into a final confirmation by an nmap scan of the network, where aside the scanning machine only two other hosts answer:

    C:\>nmap -p80
    Starting Nmap 5.50 ( ) at 2012-02-13 16:34 W. Europe
    Standard Time
    Stats: 0:00:35 elapsed; 64 hosts completed (2 up), 66 undergoing Host Discovery
    Parallel DNS resolution of 1 host. Timing: About 0.00% done
    Nmap scan report for
    Host is up (0.00s latency).
    80/tcp filtered http
    MAC Address: 00:02:XX:XX:XX:XX (Samsung Electro-Mechanics Co.)
    Nmap scan report for
    Host is up (0.00s latency).
    80/tcp filtered http
    MAC Address: 00:0F:XX:XX:XX:X (Landis+Gyr)

    Based on these observations, we can see that the whole EWZ Smart Meter setup is way more secure than the example given during the 28c3 talk. There are still possibilities to “hack around”, such as looking at the behaviour of the tablet if IP or start to answer (e.g. are they used as gateways or configuration servers?) but this would void the written agreement with the power company about not interfering with the measurement devices.

    Read all the articles about the EWZ Smart Meter using the tag SmartMeter

  • lundi, février 13 2012

    Overview of the EWZ Smart Meter after a couple of months

    Here’s finally some feedback and further screenshots of the EWZ Smart Meter system after a little more than a month of usage.

    As mentioned in the previous related article back in December, I set back then a new objective of 25 kWh per week. The historical overview below shows that this new target has only been exceeded in a major way once since then:


    This means that my annual consumption should be around 1300 kWh, way below the mean figure of a household of 2 to 3 people in Switzerland (between 3000 and 4000 kWh according to

    The historic overview gives a good insight into the consumption and allows understanding pretty closely when electricity was used:


    The measurement is very handy, as it shows in a graphical way the current electricity consumption, sampled every 2 seconds. In this example, we had a usage of around 130 w with a few spikes to 140 w. It’s especially helpful to see the impact of turning on some electricity demanding devices.



    Either the current granularity is too low or there is an issue in the measurement, but my experiment to understand how much electricity my halogen lamp was using turned out to be a fiasco:


    Once the lamp was switched at its entire performance, I would have expected an increase in the graph. Nothing happened, every avec a couple of minutes. The graph remained stable at 130 w, not taking into account the newly light lamp. Below is the overview, as well as a picture of the eco-halogen bulb I’m using – still 230 w (instead of 300 w):


    So I’m now wondering, am I just an exception by using so little electricity or is there an issue in my setup?

    samedi, décembre 17 2011

    Overview of the Smart Meter application

    Here are a few screenshots of the application running on the Archos 7. It is composed of 5 tabs:

    The first tab is composed of an indication of the current electricity consumption and a summary of how much power has been used this week. We’ll see in the last part where the number of 50.0 kWh comes from.


    The second tab gives an insight into the historical data collected by the smart meter. According to the information given in the documentation, the smart meter is able to collect up to a month of data before it gets overwritten. A part of the role of the tablet is to store for the full duration of the study these records.

    Going back to this tab, the graph can be setup per hour, day, week, month, three month or year. It also gives an insight into the power costs for the given period.


    The third tab gives an overview of the power usage versus a target consumption. We’ll see later that we can set ourselves the target for the upcoming week.


    The forth tab gives the ability to track ever update from the smart meter. It is also possible to press the start button to record the variation and calculate the overall expenture.


    Finally, the last tab is about configuration and shows a summary of this week and allows to set a new target for the upcoming week. In our case, we decided to lower the target from 50 kWh to 25 kWh next week.

    This will affect from next Monday on the weekly summary displayed on the first screen.


    - page 1 de 3