Satellite security lags decades behind the state of the art

Thousands of satellites are currently orbiting the Earth, and there will be many more in the future. Researchers from Ruhr University Bochum and the CISPA Helmholtz Center for Information Security in Saarbrücken have assessed the security of these systems from an IT perspective. They analysed three current low-earth orbit satellites and found that, from a technical point of view, hardly any modern security concepts were implemented. Various security mechanisms that are standard in modern mobile phones and laptops were not to be found: for example, there was no separation of code and data. Interviews with satellite developers also revealed that the industry relies primarily on security through obscurity.

The results were presented by a team headed by Johannes Willbold, a PhD student from Bochum, Dr. Ali Abbasi, a researcher from Saarbrücken, and Professor Thorsten Holz, formerly in Bochum, now in Saarbrücken, at the IEEE Symposium on Security and Privacy, which took place in San Francisco from 22 to 25 May 2023. The paper was awarded a Distinguished Paper Award at the conference.

Research satellites and commercial satellite put to the test

The examined satellites were two small models and one medium-sized model -- research satellites as well as a satellite of a commercial company -- which orbit the Earth at a short distance and are used to observe the Earth. Gaining access to satellites and their software was a challenge for the team, as commercial providers in particular rarely wish to reveal any details. The researchers eventually gained access through cooperation with the European Space Agency (ESA), various universities involved in the construction of satellites, and a commercial enterprise.

The team from Bochum and Saarbrücken conducted a thorough security analysis of the three models. They looked in detail at what the software running on the devices does and which communication protocols are used. They emulated the systems, i.e., rebuilt them virtually, so that they could test the software as if it were in a real satellite. "It was a very different world from the systems we usually study. For example, completely different communication protocols were used," as Thorsten Holz outlines the process.

Systems with specific requirements

Satellites orbiting the Earth can only be reached by their ground station on Earth within a time window of a few minutes. The systems must be robust against the radiation in space, and, since they can only consume a small amount of energy, they have a low power output. "The data rates are like those of modems in the 1990s," as Holz elaborates the challenges satellite developers face.

Based on the findings gained from the software analysis, the researchers worked out various attack scenarios. They showed that they could cut off the satellites from ground control and seize control of the systems, for example in order to take pictures with the satellite camera. "We were surprised that the technical security level is so low," points out Thorsten Holz, adding the following caveat with regard to potential ramifications: "It wouldn't be all that easy to steer the satellite to another location, for example, to crash it or have it collide with other objects."

Survey among developers

To find out how the people who develop and build satellites approach security, the research team compiled a questionnaire and submitted it to research institutions, the ESA, the German Aerospace Centre and various enterprises. Nineteen developers participated anonymously in the survey. "The results show us that the understanding of security in the industry is different than in many other areas, specifically that it's security by obscurity," concludes Johannes Willbold. Many of the respondents therefore assumed that satellites could not be attacked because there is no documentation of the systems, i.e., nothing is known about them. Only a few said that they encrypt data when communicating with satellites or use authentication in order to ensure that only the ground station is allowed to communicate with the satellite.

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TRAPPIST-1 planets provide clues to the nature of habitable worlds

All seven planets discovered in orbit around the red dwarf star TRAPPIST-1 could easily fit inside the orbit of Mercury, the innermost planet of our solar system.

TRAPPIST-1 is an ultra-cool red dwarf star that is slightly larger, but much more massive, than the planet Jupiter, located about 40 light-years from the Sun in the constellation Aquarius.

Among planetary systems, TRAPPIST-1 is of particular interest because seven planets have been detected orbiting this star, a larger number of planets than have been than detected in any other exoplanetary system. In addition, all of the TRAPPIST-1 planets are Earth-sized and terrestrial, making them an ideal focus of study for planet formation and potential habitability.

ASU scientists Cayman Unterborn, Steven Desch, and Alejandro Lorenzo of the School of Earth and Space Exploration, with Natalie Hinkel of Vanderbilt University, have been studying these planets for habitability, specifically related to water composition. Their findings have been recently published in Nature Astronomy.

Water on the TRAPPIST-1 Planets

The TRAPPIST-1 planets are curiously light. From their measured mass and volume, all of this system's planets are less dense than rock. On many other, similarly low-density worlds, it is thought that this less-dense component consists of atmospheric gasses.

"But the TRAPPIST-1 planets are too small in mass to hold onto enough gas to make up the density deficit," explains geoscientist Unterborn. "Even if they were able to hold onto the gas, the amount needed to make up the density deficit would make the planet much puffier than we see."

So scientists studying this planetary system have determined that the low-density component must be something else that is abundant: water. This has been predicted before, and possibly even seen on larger planets like GJ1214b, so the interdisciplinary ASU-Vanderbilt team, composed of geoscientists and astrophysicists, set out to determine just how much water could be present on these Earth-sized planets and how and where the planets may have formed.

Calculating water amounts on TRAPPIST-1 planets

To determine the composition of the TRAPPIST-1 planets, the team used a unique software package, developed by Unterborn and Lorenzo, that uses state-of-the-art mineral physics calculators. The software, called ExoPlex, allowed the team to combine all of the available information about the TRAPPIST-1 system, including the chemical makeup of the star, rather than being limited to just the mass and radius of individual planets.

Much of the data used by the team to determine composition was collected from a dataset called the Hypatia Catalog, developed by contributing author Hinkel. This catalog merges data on the stellar abundances of stars near to our Sun, from over 150 literature sources, into a massive repository.

What they found through their analyses was that the relatively "dry" inner planets (labeled "b" and "c" on this image) were consistent with having less than 15 percent water by mass (for comparison, Earth is 0.02 percent water by mass). The outer planets (labeled "f" and "g" on this image) were consistent with having more than 50 percent water by mass. This equates to the water of hundreds of Earth-oceans. The masses of the TRAPPIST-1 planets continue to be refined, so these proportions must be considered estimates for now, but the general trends seem clear.

"What we are seeing for the first time are Earth-sized planets that have a lot of water or ice on them," says ASU astrophysicist and contributing author, Steven Desch.

But the researchers also found that the ice-rich TRAPPIST-1 planets are much closer to their host star than the ice line. The "ice line" in any solar system, including TRAPPIST-1's, is the distance from the star beyond which water exists as ice and can be accreted into a planet; inside the ice line water exists as vapor and will not be accreted. Through their analyses, the team determined that the TRAPPIST-1 planets must have formed much farther from their star, beyond the ice line, and migrated in to their current orbits close to the host star.

There are many clues that planets in this system and others have undergone substantial inward migration, but this study is the first to use composition to bolster the case for migration. What's more, knowing which planets formed inside and outside of the ice line allowed the team to quantify for the first time how much migration took place.

Because stars like TRAPPIST-1 are brightest right after they form and gradually dim thereafter, the ice line tends to move in over time, like the boundary between dry ground and snow-covered ground around a dying campfire on a snowy night. The exact distances the planets migrated inward depends on when they formed. "The earlier the planets formed," says Desch, "the further away from the star they needed to have formed to have so much ice." But for reasonable assumptions about how long planets take to form, the TRAPPIST-1 planets must have migrated inward from at least twice as far away as they are now.

Too much of a good thing

Interestingly, while we think of water as vital for life, the TRAPPIST-1 planets may have too much water to support life.

"We typically think having liquid water on a planet as a way to start life, since life, as we know it on Earth, is composed mostly of water and requires it to live," explains Hinkel. "However, a planet that is a water world, or one that doesn't have any surface above the water, does not have the important geochemical or elemental cycles that are absolutely necessary for life."

Ultimately, this means that while M-dwarf stars, like TRAPPIST-1, are the most common stars in the universe (and while it's likely that there are planets orbiting these stars), the huge amount of water they are likely to have makes them unfavorable for life to exist, especially enough life to create a detectable signal in the atmosphere that can be observed. "It's a classic scenario of 'too much of a good thing,'" says Hinkel.

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New software can verify someone's identity by their DNA in minutes

Researcher Sophie Zaaijer uses the MinION, a portable DNA sequencer, to get a quick genetic readout of a sample of cells.

In the science-fiction movie Gattaca, visitors only clear security if a blood test and readout of their genetic profile matches the sample on file. Now, cheap DNA sequencers and custom software could make real-time DNA-authentication a reality.

Researchers at Columbia University and the New York Genome Center have developed a method to quickly and accurately identify people and cell lines from their DNA. The technology could have multiple applications, from identifying victims in a mass disaster to analyzing crime scenes. But its most immediate use could be to flag mislabeled or contaminated cell lines in cancer experiments, a major reason that studies are later invalidated. The discovery is described in the latest issue of eLife.

"Our method opens up new ways to use off-the-shelf technology to benefit society," said the study's senior author Yaniv Erlich, a computer science professor at Columbia Engineering, an adjunct core member at NYGC, and a member of Columbia's Data Science Institute. "We're especially excited about the potential to improve cell-authentication in cancer research and potentially speed up the discovery of new treatments."

The software is designed to run on the MinION, an instrument the size of a credit card that pulls in strands of DNA through its microscopic pores and reads out sequences of nucleotides, or the DNA letters A, T, C, G. The device has made it possible for researchers to study bacteria and viruses in the field, but its high error-rate and large sequencing gaps have, until now, limited its use on human cells with their billions of nucleotides.

In an innovative two-step process, the researchers outline a new way to use the $1,000 MinION and the abundance of human genetic data now online to validate the identity of people and cells by their DNA with near-perfect accuracy. First, they use the MinION to sequence random strings of DNA, from which they select individual variants, which are nucleotides that vary from person to person and make them unique. Then, they use a Bayesian algorithm to randomly compare this mix of variants with corresponding variants in other genetic profiles on file. With each cross-check, the algorithm updates the likelihood of finding a match, rapidly narrowing the search.

Tests show the method can validate an individual's identity after cross-checking between 60 and 300 variants, the researchers report. Within minutes, it verified the identity of the study's lead author, Sophie Zaaijer, a former member of NYGC and now a postdoctoral researcher at Cornell Tech.

To do this, the MinION matched the readout of Zaaijer's genome, gleaned from a sample of cheek cells, with a reference profile stored among 31,000 other genomes on the public database, DNA.land. Erlich's identity was verified the same way, with initial sequencing done by Columbia students in the Ubiquitous Genomics class he and Zaaijer taught in 2015.

They call their re-identification technique 'MinION sketching' which Zaaijer compares to the brain's ability to make out a bird from a few telling features in an abstract Picasso line-drawing. The MinION's genetic 'sketch' of a cell-sample is compared to a growing database of sketches -- similarly incomplete genetic profiles produced by at-home DNA-test kits like 23andMe and donated to science by consumers.

"Using our method, one needs only a few DNA reads to infer a match to an individual in the database," says Zaaijer.

The most promising use for 'MinION sketching' may be as a cheap cell-authentication tool in experimental research, say scientists familiar with its capabilities. In the study, researchers quickly matched a strain of leukemic cells sequenced by the MinION against a reference file in the Cancer Cell Line Encyclopedia database, they report. When they tried contaminating the cells with other cultures, it correctly rejected a match if contamination levels climbed above 25 percent.

The use of misidentified or contaminated cell lines in medical research is blamed for as much as a third of the estimated $28 billion spent each year on studies that can't be replicated, according to one recent study. In a 2014 essay in Science, the director of the National Institute of General Medical Sciences, Jon Lorsch, called for new policies and technologies to address the problem.

Lacking the expensive machinery needed to validate cell lines on their own, most researchers either skip validation or ship their cultures to specialized labs which can delay important findings and treatments. If an easier alternative were available, most researchers would use it, says Neville Sanjana, a core faculty member at NYGC and assistant professor at NYU's Department of Biology who works on skin and lung cancer cell lines and was not involved in the study.

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