An IMSI catcher equipment is also known as a false base station. This device also has some other names, like Stingray or Rogue Base Station. Those terms refer to a device that consists of software and hardware that allow for active and passive attacks against various mobile subscribers.
The IMSI catcher is going to attack over RANs or radio access networks. The attacking tool or the FBS is going to exploit mobile networks’ security weaknesses from various generations, including 2G, 3G, 4G, and also the latest 5G. Are IMSI catchers illegal or legal? Find the answer on this page.
Various Functions of An IMSI Catcher Equipment
Even though there are various implementations of IMSI catchers from different models, these devices have some major functions. The device is able to determine mobile phones’ IMSI numbers around it. by using the IMSI, the device will then identify the network’s mobile traffic.
After identifying the mobile traffic on a network, it can intercept and analyze the traffic. Here are some major functions of IMSI catchers.
1. Getting the IMSI
Even though there are some base stations on a home network in the area, GSM mobile phones are going to connect to a base station that emits the strongest signal. By transmitting a sufficiently strong signal, IMSI catchers legally are going to make every mobile phone in a small radius connect to it.
The catcher is going to act like the base station. First of all, the mobile station is going to be induced so that it can send the encryption capabilities to a base station. And then the catcher is going to send the command of identity request to a mobile station. The mobile station is going to respond immediately.
2. Starting network connection
An IMSI catcher equipment is able to connect to a network simply by sending the location update request. When a network responds with an identity request, an IMSI catcher is going to respond by using the stolen IMSI.
Next, the network is going to send the challenge RAND to the IMSI catcher. Since the catcher has no secret key Ki, the catcher won’t be able to respond at the beginning.
3. Finishing mobile station connection
The next thing you should know about how IMSI catcher works is that the device is going to forward the RAND as a challenge to the mobile station. The goal is to follow up on the last communication that occurred in section 3.2.1.
With the relevant Ki, the mobile station is going to calculate the response SRES that has been signed and then send it back to the catcher device. Since the device doesn’t have to verify SRES, the catcher can ignore the response while accepting the mobile station authentication to complete the connection.
Since the base station is the one that determines the GSM protocol’s encryption mode, the catcher will set the cipher to no encryption. And then it will allocate the arbitrary TMSI to a mobile station before accepting the location update.
From here, the IMSI catcher equipment will be able to communicate with a mobile station before easily getting access to any outgoing call.
IMSI Catcher Protection
Today, there is no effective way for any smartphone user to know whether their phone is connected to any IMSI catcher device. This means there is no effective way to protect your device from the catcher device. However, your device may show some signs to let you know that it connects to a catcher.
Some signs include a slow cellular connection and also a band change in the status bar, for example, the LTE band turns to a 2G. however, slow connections may also happen to users who are unaffected. Some catcher devices can even operate on mobile phones with 4G connectivity.
A specific catcher detection app is available but is only designed for Android devices. however, the app requires device rooting which is a harmful process. If you don’t want to risk your mobile device with another security hole, avoid rooting your phone just to get the catcher detection app.
And if you need the best IMSI catcher equipment, SMS Broadcaster is providing the best one for your business. This device comes with excellent features for your needs. Check out SMS Broadcaster’s Products section and you’ll find everything you need to promote your business much more effectively.