# Déjà-Vu: A Glimpse on Radioactive Soft-Error Consequences on Classical and
Quantum Computations

Antonio Nappa, Christopher Hobbs, Andrea Lanzi

###### Abstract

What do Apple, the FBI and a Belgian politician have in common? In 2003, in
Belgium there was an election using electronic voting machines. Mysteriously
one candidate summed an excess of 4096 votes. An accurate analysis led to the
official explanation that a spontaneous creation of a bit in position 13 of
the memory of the computer attributed 4096 extra votes to one candidate. One
of the most credited answers to this event is attributed to cosmic rays
i.e.(gamma), which can filter through the atmosphere. Indeed, SEUs (single
event upsets) such as bit-flips are frequent faults especially in outer space,
where ionizing radiations are very frequent. For this reason many space
capable devices mount very expensive and technically advanced memories, to
reduce risks of malfunction, breakage, or exploit. On the other hand, at
ground level, consumer devices aren’t equipped with such memories for economic
and statistical reasons. Indeed, research in the area shows that cosmic, high-
energy rays filter inside the atmosphere on a daily basis. But when they hit
our computers mostly they reach non-allocated space and systems do not notice
their effects. There are cases though, with classical computers, like forensic
investigations, or system recovery where such soft-errors may be helpful to
gain root privileges and recover data. In this paper we show preliminary
results of using radioactive sources as a mean to generate bit-flips and
exploit classical electronic computation devices. We used low radioactive
emissions generated by Cobalt and Cesium and obtained bit-flips which made the
program under attack crash. We also provide the first overview of the
consequences of SEUs in quantum computers which are today used in production
for protein folding optimization, showing potential impactful consequences. To
the best of our knowledge we are the first to leverage SEUs for exploitation
purposes which could be of great impact on classical and quantum computers.

###### Index Terms:

Side-channels, Soft-errors, Exploitation, Forensics, Security

##  I Introduction

In 2016 the FBI demanded that Apple unlock (decrypt) an iPhone 5C after the
San Bernardino’s terrorist shooting [36]. Apple, denied the decryption of the
phone alleging that it would put the privacy of millions of users at risk.
According to the news, the FBI resorted to an Israeli company, which charged
around 1M USD. The company reverse engineered the phone, which allowed the
investigation to continue. This study strives to leverage radioactive energy
emissions to obtain bit-flips on electronic devices e.g.(mobile phones,
electronic voting machines, IoT devices) for exploitation without resorting to
expensive and ad-hoc techniques. Also it shows how such radioactive emission
can impact quantum computation in a significant and dangerous way. Our
preliminary research shows that on memories (+15 years old) low radioactive
emissions (within 0.4MeV and 1.4 MeV of kinetic energy) produce SEUs and lead
a program to a crash, while on modern memory such energy is not sufficient.

Soft-Errors are a type of hardware fault that in some cases provoke a
glitch111malfunction in a system executing a program. A glitch normally can
manifest as a bit flipping its value from 0 to 1 or vice-versa. The intuition
of soft-errors generated by radioactivity is attributed to the Sci-Fi writer
Dr. Isaac Asimov, which in his book ”Caves of Steel” [3] (written in 1953),
reports hardware malfunctions due to radioactivity. Scientific proofs of such
evidence came years later. First by observing how impurities in construction
of silicon wafers could autonomously generate $\alpha$ particles222An $\alpha$
particle corresponds to a 2 proton 2 neutron particle, similar to ${}^{4}He$,
the most common form of Helium on Earth which could lead to soft-errors [21,
13], these particles are not dangerous for human health and carry very low
energy, measured in MeV. As a matter of fact $\alpha$ particles can be
shielded with a sheet of paper. Along the past century the advent of space
missions made the phenomena easier to observe at high altitudes and outside
Earth’s atmosphere. Indeed, in outer space high energy cosmic rays are free to
hit unshielded electronic circuits and provoke glitches, errors, and faults.
Recently, the introduction of quantum computers opens new avenues for these
source of errors to generate potential harmful issues. In this paper we report
preliminary results of inducing soft-errors by hitting classical circuits with
gamma-rays and low energy neutrons to break into protected systems, leveraging
bit-flips and following exploit strategies similar to RowHammer [23]. Our
technique can be leveraged for forensic investigation on locked/encrypted
electronic devices, to recover data, or to rescue a system. Moreover we
provide an overview on how such technique could impact quantum computations.

Our hypothesis is to prove that high power emissions (available at
radiotherapy clinics at an affordable cost [18, 17]) can be used to exploit
COTS (Common Off The Shelf) electronic devices and consequently allow their
exploitation [23, 15, 32, 32] or lead to wrong output of quantum computations.
This is the first attempt in scientific literature to break into a device
i.e.(classical or quantum) using radioactive sources.

##  II Related Work

Literature related to Soft-Errors appeared first in the 70s [13, 21, 30],
where such errors were generated by impurities in the manufacturing package of
memory and CPU chips. In this specific case the SEU was induced by an $\alpha$
particle. Over time, hardware manufacturers have been improving the selection
of their materials and these kinds of soft errors have disappeared.
Nonetheless, in a paper from 2017 [18], the authors show that by removing the
epoxy layer of a chip, makes very easy to generate soft errors with $\alpha$
particles. Such particles are quite common in nature even at ground level, and
hence removing the epoxy leaves the chip exposed even to innocuous radiations.
Along with research for hardware that would function at ground level there is
a huge corpus of research related to hardware that needs to function from the
stratosphere to outer space. Indeed, many papers [9, 22, 12] especially in the
field of particle physics and radiation protection for electronic devices,
have shown that it is quite common for such errors to appear. Research efforts
have been focused on observing/producing such errors at ground level with the
help of radioactive sources. In a paper from 2005 of Franco et al. [17] show
how to generate soft errors in commercial SRAM with low energy neutrons
produced at a clinical facility. With respect to SDRAM which is the most
common memory used in COTS devices, a 2018 paper from Kohler et.al [16] shows
that multiple kinds of errors (e.g. single-event effects (SEE), single bit
upsets (SEUs), multiple-bit upsets (MBUs), multiple cell upsets (MCUs), latch-
up (SEL), and functional interrupt (SEFI).) can be reproduced by using
ionizing radiations emitted by devices in a clinical facility treating
oncological patients. Schroeder et al. [28] show how the impact of cosmic rays
on electronic devices change between sea level and above, closer to space. On
a daily basis, computers are hit by cosmic rays which can provoke glitches,
but in most cases they hit memory which is free, so the running system is not
impacted. Indeed, a paper from 2011 shows how such phenomena can influence the
DNS system [7]. Tezzaron Semiconductor in 2004 reports in a white paper how
such errors may appear within a a range of 0.2 and 1 per day in COTS memories
[29]. Even if there is no evidence of effects of SEUs in quantum hardware in
literature it is evident that everything that is based on silicon and similar
semiconductors is subject to the same physical laws.

##  III Approach

The intuition of this work, is to leverage ionizing radiations to induce bit-
flips in specific areas of classical computer memory. We have devised two
techniques for this attack to take place. One is by using page table spraying
[23] and the second requires minimal reverse engineering of the memory
locations of the DUT (Device Under Test). The first attack works where there
is at least user-level privilege, while the second works when the device is
locked. We have performed multiple tests with low energy ionizing radiation
(within 0.4 and 1.4 MeV) with Cesium and Cobalt on the Raspberry Pi 4 platform
with 8 GB and 4 GB of memory. We also have tested an older IBM ThinkPad T41p,
which was manufactured in 2003. Our final goal beyond the proof of concept of
exploiting a user-land program similar to the RowHammer [23] technique, is to
unlock a mobile phone or any kind of device which is protected and needs to be
unlocked for legal reasons or for data rescue. Our technique also impacts
quantum hardware given its high sensitivity to environmental variations, see
Section V-B for detailed explanation.

To explain the nature of radioactive ionizing emissions, Figure 1 shows the
decay of Cobalt, which emits beta and gamma rays. Radioactive materials are
unstable by nature and they evolve into other materials over time by losing
energy in the form of particles (i.e. electrons). Hence, by losing electrons
one material transforms into another over time. For example Cobalt-60 isotope
after approximately 5 years transforms into Nickel-60. Figure 1 shows the
decay of Cobalt which produces different source of energy, $\beta$ and
$\gamma$ radiations, which carry different kinetic energies, between 0.31 MeV
and 1.33 MeV. Radioactive decay produces ionizing radiations which affect
electronic circuits as shown in many papers [26, 20, 18, 17] and in circuit
manufacturing recommendations guides [31].

The ratio of these emissions varies according to the materials. The more
unstable and dangerous the materials are, the more radiations emits. Enhancing
the probability of successful SEUs generation. Understanding the ratio of our
soft-error inducing approach, requires time and study of materials and
different devices along with their manufacturing process. This holds true in
both scenarios i.e. (classical and quantum computers).

Figure 1: Cobalt Decay Ratio

#### Bit-flips in the wild.

Multiple papers [24, 29] show that SEU happen spontaneously due to cosmic
radiations, coming from sources in outer space. More recent papers [26, 20],
show that errors can be induced even in very recent electronics. In another
paper [1], shown in Figure 2 it was possible to observe in the geographical
zone of Tibet, radiations beyond 100TeV of energy which could eventually
permanently damage the circuits. However, the number of photons with such
energy was 24, which still is very small compared to the number of bits that
are present in COTS memory chips. Figure 3 shows how cosmic rays when hitting
our atmosphere generate different sources like a particle accelerator does
when particles collide. Daily, some of these secondary charges impact
classical computer memories and generate SEUs, but the low probability of such
events to happen at a sufficient rate makes natural sources not reliable to be
used as a potential exploit avenue, at least in classical computing.

Figure 2: High Energy Experiment Realized in Tibet in 2019 Figure 3: Example
of Cosmic Ray Decay in Earth’s Atmosphere

#### Bit-flips from radioactive sources.

These events are intentionally generated with the help of radioactive
materials, at a very small distance from the DUT in a controlled laboratory
and very often in vacuum, either with strong radiation sources [26, 20, 17] or
with innocuous $\beta$ radiations by removing the epoxy layer of a chip [18].
Some of these experiments demonstrate the ability of generating failures in ML
models and opening space for non conventional adversarial attacks. In 2020
Oliveira et al [26], show how both thermal neutrons and high energy neutrons
can generate different kinds of soft errors and alter the output of a
computation. The ITU (International Telecommunication Union) recommends [31]
to test electronic devices against ionizing radiations with a particle
accelerator with different sources and secondary charges generated by hitting
other particles such the ones contained in water (Oxygen and Hydrogen). Figure
7 shows our experiment with Cobalt and water to generate a secondary source
thermal neutrons. Table I shows the results of the ITU test with different
kinds of silicon hit by a neutron (+n) carrying different energies generated
from a particle accelerator such as the one found in hospitals for cancer
treatment. Such experiments result in an emission of an atom of a different
material such as Magnesium (Mg) or Aluminium (Al) and a proton (p) or an alpha
particle ($\alpha$) and possible generation of SEUs.

#### Quantum Computation Impact.

The consequences of radioactive emissions, induced on purpose or generated by
natural events on quantum hardware have not been studied and understood yet.
Though, the impact of errors and their correction in quantum computations play
a fundamental role [19] in such machines. In Section V-B we give a first
intuition on the potential impactful consequences of quantum circuit
malfunctioning.

Si - Neutron reactions | Energy
---|---
28Si + n –>28Al + p | 3.999 MeV
28Si + n –>25Mg + $\alpha$ | 2.749 MeV
29Si + n –>29Al + p | 3.009 MeV
29Si + n –>26Mg + $\alpha$ | 35.00 KeV
30Si + n –>30Al + p | 8.040 MeV
30Si + n –>27Mg + $\alpha$ | 4.341 MeV
TABLE I: ITU Results of bombarding different Silicon Isotopes with neutrons at
different energies

###  III-A Soft-Error Hunting on Classical Computers

Understanding the precise location of a single bit-flip is quite difficult
given the density of recent memory chips and their sizes. However, previous
approaches [32] have found avenues to reproduce bit-flips in a deterministic
way leveraging hardware manufacturing imperfections. In our case, which uses
external radioactive sources, the position of a single bit may be smaller than
a square nanometer. Researchers [16, 38] use lasers and Monte Carlo simulation
to understand the precise location of an error. To this extent, Carmon et al.
[5] show how to recover memory content with photonic side channels, which can
help to understand precise bit locations on a small budget. For our
preliminary experiment we chose a program to read memory and compare the
initial pattern, for example 0xFF and checking its consistency during the
irradiation period. Previous literature [18] shows that different initial
patterns may lead to different error rates. The first RowHammer [23]
implementation increases the attack likelihood from 2% to 30% by spraying the
page table structure of a benign program in user space. Creating a reference
to the program memory in a large section of the available free memory, which
is bigger than the memory occupied by the program itself. By spraying the page
table, it is possible to hit a sensitive bit once or many times which can be
flipped and used to escalate privileges. Other approaches [38] use high
precision laser which could lead to deterministic bit-flips and reduce risks
due to radioactivity. Our initial approach uses ionizing i.e. (emitting
particles) radiations which exhibit a statistical behavior as the quantum
mechanics theory describes [8]. Our intuition is to shield eventual sensitive
regions of the circuit board with lead and and hit only the memory chip. In
this way, we are very likely to accomplish exploitation without altering the
correct duty-cycle of the DUT. As demonstrated previously [23, 15] by spraying
the page table of a suid program through 4GB of memory gives a 30% chance to
hit the correct byte and escalate privileges.

###  III-B Exploit Strategies on Classical Computers

#### Basic Reverse Engineering + Bit-Flip.

This novel technique requires basic knowledge of the DUT, particularly its
architecture and some basic information that can be find in the firmware.
Indeed firmware images [4, 11] carry very specific information within the
binary file. For example in baseband chips such as Samsung’s Shannon (ARM
Cortex R7) there’s no page table and MMU (Memory Management Unit). Hence, some
basic knowledge of the firmware and the architecture can lead to a successful
exploit starting from a SEU. The difficulty is to understand where exactly
it’s necessary to produce the SEU. For this reason we have proposed shielding
the device with lead as shown in the sketch of Figure 4.

#### Bit-Flip + Privilege Escalation.

This technique has been already demonstrated by Seaborn et al. [37]. In our
case, we leverage a different source of SEUs (i.e. instead of RowHammer [23]
we use ionizing radiations). The feasibility of our approach resides in the
ratio of SEU generation with respect to the size of page-table spraying.

Figure 4: A Sketch on how increase probability to shoot on target using lead
shields

##  IV Preliminary Evaluation on Classical Hardware

We have used three different devices: an IBM Thinkpad T41p of 2003 equipped
with 2GB of RAM, a more recent Raspberry Pi 4 with 4GB of RAM, and a Raspberry
Pi 4b with 8GB of Ram.

Tables II and III show the results of gamma-ray exposure of the T41p with
Cobalt and Cesium respectively. As a first experiment we filled the memory
with different patterns 0xFF, 0X00, 0X41 which generate different bit
patterns. Every pattern was tested over a period of 20 minutes with a Cobalt
and Cesium source. We were able to observe a total of 68 bit-flips with Cobalt
and 13 with Cesium. After the preliminary successful test the device was ready
to be exploitable with the technique explained by Seaborn et al. [37], our
attempt with gamma-rays lead the ping program (which runs with root
privileges) to crash two times with segmentation fault. The probability of
exploitation given the low number of generated SEUs per second (1 every 17
seconds on average), combined with RAM refresh rate (64ms), page table size
and RAM constructive process, gave us approximately an average probability of
1% to shoot on target. More sophisticated techniques, such as lasers [38, 16]
may lead to high probability or even deterministic success rate. It is also
worth noting, as it is possible to evince from Figure 6 that all the SEUs were
observed with the DUT as close as possible to the to the radioactive source.
Figure 6 shows a DUT at less than 5cm from the radioactive source. The
laboratory was equipped with a camera and a secondary laptop connected via
Ethernet cable to the DUT. The camera was pointing at the screen of the laptop
connected to the DUT to observe in real time the result of the experiments.
Moreover Figure 5 shows the console to select duration and radioactive source
for the experiment.

Figure 5: Emission Control Console Element | Device | Used Memory | Pattern | Time | Flips
---|---|---|---|---|---
| Co($\sim$1.5MeV)
---
T41p | 1GB | 0xFF | 1200s | 27
| Co($\sim$1.5MeV)
---
T41p | 1GB | 0x00 | 1200s | 22
| Co($\sim$1.5MeV)
---
T41p | 1GB | 0x41 | 1200s | 19
TABLE II: IBM T41p - Cobalt Gamma Ray Exposure Element | Device | Used Memory | Pattern | Time | Flips
---|---|---|---|---|---
| Cs($\sim$0.6MeV)
---
T41p | 1GB | 0xFF | 1200s | 7
| Cs($\sim$0.6MeV)
---
T41p | 1GB | 0x00 | 1200s | 3
| Cs($\sim$0.6MeV)
---
T41p | 1GB | 0x41 | 1200s | 3
TABLE III: IBM T41p - Cesium Gamma Ray Exposure

The experiments with the more recent (dated 2019) and more dense memories
(higher bitrate for square millimeter) of the Raspberry Pi devices led to zero
SEUs. According to the ITU report [31] from 2018 higher energies (above 5MeV)
and heavier particles are needed i.e. (neutrons instead of photons) to
generate SEUs. Nonetheless even using a water tank as shown in Figure 7 was
not sufficient to generate secondary charges which could significantly impact
the memory of the DUT. Moreover we left one Raspberry Pi 4b with 8GB of memory
with 4GB allocated with the pattern 0xFF during 10 months without noticing any
SEU. This does not exactly means such events did not happen, but reading the
entire memory takes time and it is a sequential operation, per byte operation.
Hence our reading single threaded loop routine may just have missed the SEUs
because of its delay in reading and comparing memory values.

Figure 6: Our Experiment testbed, DUT circled close to the radioactive sources
Figure 7: Raspberry Pi4B Under Test with a Water Tank

##  V Preliminary Discussion and Future Work

###  V-A Classical Computers

Our preliminary experiments show that our approach it is likely to work (81
bit-flips were generated with gamma-rays) on 20 years old devices and we
successfully crashed a suid program 2 times. But for recent devices it will be
necessary to access heavier particles i.e. (neutrons or protons) instead of
photons (gamma-rays) and higher kinetic energy (above 5MeV). The cost of such
a technique is much cheaper than performing a complete reverse engineering of
the device memory looking for a vulnerability. A few sessions of advanced
cancer treatment (hardron-therapy) [34] cost about a tenth ($\sim$15K USD) of
what any reverse engineering company may ask from law enforcement to unlock a
device ($\sim$1M USD) [36]. Moreover our technique is extremely portable, fast
and it needs small customization. It requires knowledge of the memory
structure and architecture of the DUT. Such information is stored directly in
firmware images while other information maybe inferred from similar unlocked
devices. We contacted multiple clinical facilities across Europe asking to
test our approach with hardron-therapy. In Europe there are only about fifteen
centers and due to the pandemic, our access and mobility was restricted. We
expect our approach to work given the energy that such facilities are capable
of generating. The trade-off that we will be seeking will be to avoid
permanent damage to the DUT in order to obtain stable results and reliable
evidence for law enforcement.

###  V-B Quantum Computers

Radioactive based SEUs maybe of great impact on quantum computers which have
extreme sensitivity to minimal environmental variations e.g (temperature,
vibrations) given their sub-atomic scale, even if shielded, not all sources of
SEUs can be avoided [1, 28]. In particular, we refer to the process of quantum
decoherence and quantum error correction [19] to obtain meaningful results
from quantum computations. To this extent we consider of particular interest
the NP problem of protein folding which can be greatly optimized by quantum
annealing computers [27] such as the one developed by D-Wave [6], based on the
quantum annealing meta-heuristic, fist proposed by Apolloni et al. [2] and
furtherly developed by Kadowaki et al. [14]. In such process an error can lead
to biological anomalies that can provoke diseases such as bovine spongiform
encephalopathy [25]. It is trivial to evince how impactful this attack could
be in a delicate processes such as vaccine development [10], especially during
pandemic times. Where making less errors can save human lives.

###  V-C Future works

In future, we aim to explore less harmful, cheaper and more deterministic
sources of SEUs i.e., lasers [38, 16]. Which, are capable of generating SEUs
with high precision on classical machines, allowing our attack to be deployed
outside a protected facility. Also, removing the epoxy layer of chips [18]
requires very low effort to obtain SEUs with harmless radiations, though it
damages the device irreversibly and it may raise concerns especially in
forensics investigations. We will to test our approaches both on conventional
and quantum machines.

###  V-D Countermeasures

We have contacted the authors of Drammer and GuardION [32, 33], explaining our
attack strategy. Our analysis lead to the conclusion that GuardION is not
effective against externally provoked SEUs. Still, ECC (Error-correcting code)
memories and magnetorestive memories (MRAM) are not susceptible to our kind of
attack. Indeed they are used normally in high altitude operating devices. The
impact of our approach resides on the fact that such memories are more
expensive and slower than memory used in COTS devices. With respect to quantum
computers, since their technology is very recent, several approaches could be
taken to improve their safety and security, starting from the basic building
blocks (Qbits) for example by realizing Qbit gates resistant to external
interfences.

##  VI Ethical Considerations

Using ionizing radiations to provoke glitches in an electronic system is a
potentially harmful, life threatening activity, which needs expert supervision
and should never be deployed outside shielded environments. Generating such
emissions maybe possible with relatively inexpensive material at home [35],
though such rudimentary techniques should never be pursued, not even for test
purposes. This is the main reason why this paper is preliminary, because
during pandemic times it was very hard to access safe facilities to complete
extensive experiments.

##  VII Conclusion

Using radioactive soruce i.e. (Ionizing Radiations) to produce SEUs such as
bit-flips is not a novel idea per-se [26, 20, 18, 17, 16, 28]. Our paper makes
an effort to understand the possibility to use such events as a potential
source of exploitation or a source of harmful errors on quantum machines. Our
technique is helpful for law enforcement to unlock devices in a cheap and
affordable way or to rescue a system, plus it can lead to safer quantum
hardware development. Our preliminary results are promising and we are waiting
to access a hardron-therapy facility to further verify our hypothesis.

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