Category: bladeRF

Exploring the Limits of General Purpose SDR Devices

Back in August 2019 the Chaos Communication Camp was held in Germany. This is a 5 day conference that covers a variety of hacker topics, sometimes including SDR. At the conference Osmocom developer Harald Welte (aka @LaF0rge) presented a talk titled "The Limits of General Purpose SDR devices". The talk explains how general purpose TX capable SDRs like HackRFs and LimeSDRs have their limitations when it comes to implementing advanced communications systems like cellular base stations.

If you prefer, the talk can be watched directly on the CCC website instead of YouTube.

Why an SDR board like a USRP or LimeSDR is not a cellular base station

It's tempting to buy a SDR device like a LimeSDR or USRP family member in the expectation of operating any wireless communications system out there from pure software. In reality, however, the SDR board is really only one building block. Know the limitations and constraints of your SDR board and what you need around it to build a proper transceiver.

For many years, there's an expectation that general purpose SDR devices like the Ettus USRP families, HackRF, bladeRF, LimeSDR, etc. can implement virtually any wireless system.

While that is true in principle, it is equally important to understand the limitations and constraints.

People with deep understanding of SDR and/or wireless communications systems will likely know all of those. However, SDRs are increasingly used by software developers and IT security experts. They often acquire an SDR board without understanding that this SDR board is only one building block, but by far not enough to e.g. operate a cellular base station. After investing a lot of time, some discover that they're unable to get it to work at all, or at the very least unable to get it to work reliably. This can easily lead to frustration on both the user side, as well as on the side of the authors of software used with those SDRs.

The talk will particularly focus on using General Purpose SDRs in the context of cellular technologies from GSM to LTE. It will cover aspects such as band filters, channel filters, clock stability, harmonics as well as Rx and Tx power level calibration.

The talk contains the essence of a decade of witnessing struggling SDR users (not only) with running Osmocom software with them. Let's share that with the next generation of SDR users, to prevent them falling into the same traps.

The Limits of General Purpose SDR devices

Using a Software Defined Radio to Send Fake Presidential Alerts over LTE

Modern cell phones in the USA are all required to support the Wireless Emergency Alert (WEA) program, which allows citizens to receive urgent messages like AMBER (child abduction) alerts, severe weather warnings and Presidential Alerts.

In January 2018 an incoming missile alert was accidentally issued to residents in Hawaii, resulting in panic and disruption. More recently an unblockable Presidential Alert test message was sent to all US phones. These events have prompted researchers at the University of Colorado Boulder to investigate concerns over how this alert system could be hacked, potentially allowing bad actors to cause mass panic on demand (SciHub Paper).

Their research showed that four low cost USRP or bladeRF TX capable software defined radios (SDR) with 1 watt output power each, combined with open source LTE base station software could be used to send a fake Presidential Alert to a stadium of 50,000 people (note that this was only simulated - real world tests were performed responsibly in a controlled environment). The attack works by creating a fake and malicious LTE cell tower on the SDR that nearby cell phones connect to. Once connected an alert can easily be crafted and sent to all connected phones. There is no way to verify that an alert is legitimate.

Spoofed Presidential Alerts Received on a Galaxy S8 and iPhone X.
Spoofed Presidential Alerts Received on a Galaxy S8 and iPhone X.

SigintOS: A Linux Distro for Signal Intelligence

Recently we've heard of a new Linux distribution called SigintOS becoming available for download. SigintOS is an Ubuntu based distribution with a number of built in signal intelligence applications for software defined radios such as RTL-SDRs and other TX capable SDRs like the HackRF, bladeRF and USRP radios.

The distro appears to be very well executed, with a built in GUI that grants easy access to the some common sigint tools like an FM and GPS transmitter, a jammer, a GSM base station search tool and an IMSI catcher. SigintOS also has various other preinstalled programs such as GNU Radio, gr-gsm, YatesBTS, wireshark and GQRX.

The OS also teases an LTE search and LTE decoder which to access requires that you get in contact with the creators, presumably for a licencing fee. Regarding an LTE IMSI catcher they write:

LTE IMSI Catcher is not myth!

Due to the nature of LTE base stations, the capture of IMSI numbers seems impossible. LTE stations use GUTI to communicate with users instead of IMSI. The GUTI contains the temporary IMSI number called T-IMSI. This allows the operator to find out who is at the corresponding LTE station who is authorized to query T-IMSI information.

Can the GUTI number be found?
Answer Yes!

How to find GUTI and T-IMSI numbers?
Can be found with the help of SigintOS …

For detailed information [email protected]

The image comes as a 2GB ISO file, and it's possible to run it in WMWare or VirtualBox.

SIGINTOS IMSI Catcher
SigintOS IMSI Catcher

Industrial Machines like Cranes, Excavators Can Easily be Hacked with Software Defined Radios

Recently, the RF research team at Trend Micro released a very nice illustrated report, technical paper and several videos demonstrating how they were able to take control of building cranes, excavators, scrapers and other large industrial machines with a simple bladeRF software defined radio. Trend Micro is a well known security company mostly known for their computer antivirus products.

Trend write that the main problem stems from the fact that these large industrial machines tend to rely on proprietary RF protocols, instead of utilizing modern standard secure protocols. It turns out that many of the proprietary RF commands used to control these machines have little to no security in place.

A Forbes article written about the research writes:

Five different kinds of attack were tested. They included: a replay attack, command injection, e-stop abuse, malicious re-pairing and malicious reprogramming. The replay attack sees the attackers simply record commands and send them again when they want. Command injection sees the hacker intercept and modify a command. E-stop abuse brings about an emergency stop, while malicious re-pairing sees a cloned controller take over the functions of the legitimate one. And malicious reprogramming places a permanent vulnerability at the heart of the controller so it can always be manipulated.

So straightforward were the first four types of attack, they could be carried out within minutes on a construction site and with minimal cost. The hackers only required PCs, the (free) code and RF equipment costing anywhere between $100 and $500. To deal with some of the idiosyncracies of the building site tech, they developed their own bespoke hardware and software to streamline the attacks, called RFQuack.

Being a responsible security firm, Trend Micro has already notified manufacturers of these vulnerabilities, and government level advisories (1, 2) and patches have already been rolled out over the last year. However the Forbes article states that some vulnerabilities still remain unpatched to this day. Of interest, the Forbes articles writes that for some of these vendors the simple idea of patching their system was completely new to them, with the firmware version for some controllers still reading 0.00A.

The videos showing the team taking control of a model crane, real crane and excavator are shown below. The video shows them using bladeRF 2.0 SDRs which are relatively low cost TX/RX capable software defined radios. We also recommend taking a look at Trends web article as it very nicely illustrates several different RF attack vectors which could apply to a number of different RF devices.

In the past we've also posted about similar serious RF attacks to infrastructure and machines that reveal the vulnerability and disregard to wireless security present in everyday systems. These include vulnerabilities like taking control of city disaster warning sirens, GPS spoofing of car navigation systems, hacking wireless door systems on cars, and revealing hospital pager privacy breaches.

Trend Micro Illustrates Replay Attacks
Trend Micro Illustrates Replay Attacks

Crane hacking Pt 1

Crane hacking Pt 2

bladeRF 2.0 micro: New 47 MHz – 6 GHz, 56 MHz bandwidth, 2×2 MIMO SDR for $480

Nuand have recently released their new bladeRF 2.0 micro software defined radio. The SDR has a frequency range of 47 MHz to 6 GHz on TX and 70 MHz to 6 GHz on RX, a bandwidth of up to 56 MHz, a 12-bit ADC and has 2 RX and 2 TX radios.

There are two options for sale, the US$480 xA4 version and the US$720 xA9 version. The differences between the two appear to be entirely in the FPGA, with the more expensive version having an FPGA that contains many more logic elements which means that more DSP hardware can be synthesized on it. The RF transceiver chip used is the AD9361, which is the chip used on most high end SDRs like USRP's.

The bladeRF 2.0 micro is the next-generation 2x2 MIMO, 47MHz to 6GHz frequency range, off-the-shelf USB 3.0 Software Defined Radio (SDR) that is easy and affordable for students and RF enthusiasts to explore wireless communications, yet provides a powerful waveform development platform expected by industry professionals.

Support is available for Linux, macOS, and Windows. The bladeRF libraries, utilities, firmware, and platform HDL are released under open source licenses, and schematics are available online. The FPGA and USB 3.0 peripheral controller are programmable using vendor-supplied tools and SDKs that are available online, free of charge.

The bladeRF 2.0 micro features support for: GNU Radio via gr-osmosdr, Pothos via SoapySDR, SDRange, SDR Console, SDR # via sdrsharp-bladeRF, YateBTS, OpenAirInterface, srsUE & srsLTE, MathWorks MATLAB® & Simulink® via libbladeRF bindings.

The bladeRF 2.0 micro
The bladeRF 2.0 micro