The Vampires and the bats behind SS7

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But what are the impacts of not having a strong Signalling Firewall?

Signaling System No. 7 is presented under various denominations:

  • Common Channel Signalling System 7 (CCSS7) in the US,
  • Common Channel Interoffice Signaling 7 (CCIS7) in the UK or
  • N7 (Signalisierungssystem Nummer 7) in Germany

These are just fairly similar names used for the protocol suite that most telecommunication operators around the world use to communicate with each other. It also performs number translation, local number portability, prepaid billing, SMS and other services.

But what makes it such a hot topic is the technical flaw found in its system – one of the biggest infrastructure loopholes in the telecom web which has become a source of fear and paranoia.

The Impact on Subscribers

Would a random hacker choose precisely you out of the billions and billions of users linked to this structure? Most likely not, unless you’re a public figure of significant importance, but the real story is that it’s not so easy to infiltrate someone’s privacy through this weakness either — it requires a great deal of skills and time. However, it is fairly easy for the mainstream media to blow things out of proportion, and maybe it is what people need in order to start taking more precautions even on their phones – it is no longer a device to just call and text on, it’s a small and complex computer that contains almost all of our data and private conversations. Sensitive data needs sensible measures, and threats like network spoofing, phishing and spurious product placement are huge problems anyone can deal with if they are not educated on the telltale signs of a possible intrusion.

What can hackers do once they have access to the SS7 system?

They can read your text messages, listen to your calls, track your location – all those things your phone network provider and security services can do. They can also intercept the two-step verifications your bank or your email accounts need in order to perform certain actions, such as purchases and log-ins.

No need to panic – this knowledge has been in the hands of the experts for years and years before it was exposed in 2014 by the German security researcher Karsten Nohl, so it is not news; there won’t be a sudden flood of hackers trying to invade people’s phones for the sake of it and unfortunately, there isn’t much a standard user profile can do without a certain amount of privileges.

Your location will always be tracked by your MNO and the only way to remain entirely untraceable is to turn off your phone. The usage of OTT (over-the-top) apps like WhatsApp, Viber, etc. and voice-over-data services will make it possible for you to avoid the flow of information through the SS7, but is anything hackable? Technically yes.

Checking your bank account on a public Wi-Fi connection might not be the best idea, nor is the authentication of random apps demanding to be downloaded and installed onto your phone – these are the logical measures anyone can apply to not foolishly expose themselves to attacks.

The Background to this research

Hacking your Phone, an episode released by CBS’ 60 minutes sparked quite the controversy after its release and if you look past the comical blend of movie scenes from Skyfall and the cliché basement setting (as if hackers only live in basements), you might filter out the aforementioned facts. The format in which it was presented leaves a lot to be desired as the show seems to rely too much on theatrics, clickbait questions and a questionable group of hackers, but it makes a very important point crystal clear – in this interconnected world we live in, you can absolutely not trust your technology even in the comfort of your own home.

SS7 is not a hundred percent secure and was probably never meant to be – it’s functionality and general efficiency that made it the backbone of almost every MNO on the planet. It has many variants, but most networks use protocols defined by the American National Standards Institute and the European Telecommunications Standard Institute, with the notable exception of China and Japan who have their own national (TTC) variants.

But in order to properly educate people on security, it is vital to represent these facts accurately without the embellishments of drama and fear. We are all vulnerable to attacks, but spreading misinformation leads to unnecessary outrage; the supposed hacker on the show was granted access to SS7 by the German government and he told the presenter to download unsolicited software which would be a huge red flag for anyone, even to a person without much knowledge on mobile security. We’ve had computers for far longer than smart phones, and we all know better than to authorise the installation of a random toolbar or to click on flashing, epilepsy-inducing pop ups and ads.

No, you are not safe and you will most likely never be. There are real threats lurking nearby, but abstaining from using Wi-Fi in public places for sensitive operations, keeping your eyes peeled and questioning everything is probably your best defence, otherwise you will inevitably invite the vampire into your own home. Also, if you are that intensely paranoid, then maybe you should never become famous!

Article by Polina Hristova Journalist at ROCCO


Signalling Firewall Market Intelligence Research starts next week…