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TechScape: How one man stopped a potentially massive cyber-attack - by accident

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How was your Easter bank holiday? Did you use it well by, for instance, preventing a globally destructive cyber-attack? No? Try harder, then.

This weekend, a cautious, longstanding and very nearly successful attempt to insert a backdoor into a widely used piece of open-source software was thwarted - effectively by accident. From Dan Goodin at Ars Technica:

Researchers have found a malicious backdoor in a compression tool that made its way into widely used Linux distributions, including those from Red Hat and Debian.

Because the backdoor was discovered before the malicious versions of xz Utils were added to production versions of Linux, "it's not really affecting anyone in the real world", Will Dormann, a senior vulnerability analyst at security firm Analygence, said in an online interview. "BUT that's only because it was discovered early due to bad actor sloppiness. Had it not been discovered, it would have been catastrophic to the world."

The attempted hack is what is known as a "supply chain" attack. By carefully and slowly pushing updates to a little-known compression tool shipped with some Linux distributions, a free and open-source operating system, the attacker very nearly ended up with a backdoor to millions of computers at once. Whether the intention was to bide their time and then use that access for a mass hacking campaign or to execute a very patient and targeted attack on a single user is unclear at this time, though the patient and methodical nature of the attack is enough to have observers speculating that a state actor was behind it.

The backdoor itself was added to the tool by one of its two main developers, who had spent three years making real and useful contributions and the past two being one of the two official maintainers. There is still the chance the account was compromised, but if it was, it was an extremely cautious takeover: the malicious code was added to the software periodically over a long period of time, with plausible explanations given every time, and when the final backdoored version was complete, the same user headed over to the developer site for one popular version of Linux to ask that it use the updated version as soon as possible since it supposedly fixed critical bugs.

And it came so close to being public. The backdoored version was shipped in the beta versions of three different versions of Linux, and for two days, in the main release of one distribution, Kali Linux. When there, it allowed someone with the right private key to start a new encrypted connection and hijack the machine entirely.

So how was it spotted? A single Microsoft developer was annoyed that a system was running slowly. That's it. The developer, Andres Freund, was trying to uncover why a system running a beta version of Debian, a Linux distribution, was lagging when making encrypted connections. That lag was all of half a second, for logins. That's it: before, it took Freund 0.3s to login, and after, it took 0.8s. That annoyance was enough to cause him to break out the metaphorical spanner and pull his system apart to find the cause of the problem.

Many hands make light work, and many eyes make shallow bugs. That's the idea, at least, and sometimes it works. We discussed last month the ways in which the open source world can fail to live up to expectations:

Giving software away for free is great for a whole host of reasons - but quite bad at funding continued development of that software. There have been loads of attempts to fix that, from models of development where the software is free but the support is paid, to big companies directly hiring maintainers of important open-source projects. Lots of projects have ended up in a tip or supporter-focused model (remind you of anyone?), which can work for big complex tasks but falls down for some of the simplest - yet most widely used - pieces of work.

The attack on xz Utils nearly became another example of the risks of relying on volunteer work to underpin some of the most important digital infrastructure in the world. A harried maintainer with little time to spare on a side project was suddenly offered help, and came under pressure to accept it - likely from exactly the same group, posting under a few fake names. Slowly cuckooed out of his own project, things nearly turned very nasty indeed.

But this case also shows the benefits of the approach. Supply chain attacks aren't unique to the open source world, and the vague structure of the attack - getting a job building an underexamined component of critical infrastructure, and slowly and carefully working to introduce a secret weakness into it - is something that can, and does, happen in normal businesses too.

What doesn't happen is being able to tear apart the problematic software piece by piece, and track down exactly the moment when a malicious backdoor was introduced. If a supply chain attack succeeds against a closed business like Apple or Google, even discovering it is there at all is wildly difficult for third-parties, and fixing it is effectively impossible.

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Don't forget Office

Microsoft Teams app. Photograph: Dado Ruvić/Reuters

There's been a lot of discussion of tech antitrust recently - including in this newsletter - largely focusing on two main trends: on the one hand, the rise of AI, and what the enormous data and compute demands of the sector mean for competition; and on the other, the increasing tension caused by "gatekeepers", in the EU's language, who are generally seen as not being monopolists in the classical sense, but who nonetheless hold market-warping powers.

And then there's Microsoft. Despite losing the most famous tech antitrust case in history and being the second largest publicly traded company in the world, the Windows factory has sort of flown under the radar. Even the Activision Blizzard acquisition, while the subject of intense scrutiny and a decisive moment in the CMA's growing self-confidence, basically ended up being passed.

So it's sometimes weird to be reminded that, no, actually, doing things like "cloning a major piece of business software and then shipping it for free to all users of your own business software suite" is pretty squarely the sort of thing that regulators look down on. And so, Reuters reports:

Microsoft will sell its chat and video app Teams separately from its Office product globally, the US tech giant said on Monday, six months after it unbundled the two products in Europe in a bid to avert a possible EU antitrust fine.

The European Commission has been investigating Microsoft's tying of Office and Teams since a 2020 complaint by Salesforce-owned competing workspace messaging app Slack.

Since it launched in 2017, Teams has, it is fair to say, utterly trounced Slack in the enterprise market. How much of that is due to the fact that Microsoft was already dominant in the market for enterprise office software and used that position to cross-subsidise its own free competitor to Slack? It's impossible to say but the answer is unlikely to be "not at all". Will reversing that now, years after Teams overtook Slack by user count, change things? Answers on a postcard, but not a Teams message, please - the Guardian uses Google Chat.

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