Good evening crypt dwellers. Welcome to the Graveyard shift, where the most interesting, scary malware and cyber-threats are discovered and analysed.

In this edition, we look at the untold story of the NotPetya Ransomware, one of the worst cyber attacks in history. This excerpt was taken from the book "Sandworm", which was written by a fellow dungeon keeper and a WIRED senior writer, Andy Greenberg.

It was a perfect sunny summer afternoon in Copenhagen when the world’s largest shipping conglomerate began to lose its mind.

The headquarters of A.P. Møller-Maersk sits beside the breezy, cobblestoned esplanade of Copenhagen’s harbour. A ship’s mast carrying the Danish flag is planted by the building’s northeastern corner, and six stories of blue-tinted windows look out over the water, facing a dock where the Danish royal family parks its yacht. In the building’s basement, employees can browse a corporate gift shop, stocked with Maersk-branded bags and ties, and even a rare Lego model of the company’s gargantuan Triple-E container ship, a vessel roughly as large as the Empire State Building laid on its side, capable of carrying another Empire State Building-sized load of cargo stacked on top of it.

That gift shop also houses a technology help centre, a single desk manned by IT troubleshooters next to the shop’s cashier. And on the afternoon of June 27, 2017, confused Maersk staffers began to gather at that help desk in twos and threes, almost all of them carrying laptops. On the machines’ screens were messages in red and black lettering. Some read “repairing file system on C:” with a stark warning not to turn off the computer. Others, more surreally, read “oops, your important files are encrypted” and demanded a payment of $300 worth of bitcoin to decrypt them.

Across the street, an IT administrator named Henrik Jensen was working in another part of the Maersk compound, an ornate white-stone building that in previous centuries had served as the royal archive of maritime maps and charts. (Henrik Jensen is not his real name. Like almost every Maersk employee, customer, or partner interviewed, Jensen feared the consequences of speaking publicly for this story.) Jensen was busy preparing a software update for Maersk’s nearly 80,000 employees when his computer spontaneously restarted.

He quietly swore under his breath. Jensen assumed the unplanned reboot was a typically brusque move by Maersk’s central IT department, a little-loved entity in England that oversaw most of the corporate empire, whose eight business units ranged from ports to logistics to oil drilling, in 574 offices in 130 countries around the globe. Jensen looked up to ask if anyone else in his open-plan office of IT staffers had been so rudely interrupted. And as he craned his head, he watched every other computer screen around the room blink out in rapid succession.

“I saw a wave of screens turning black. Black, black, black. Black black black black black,” he says. The PCs, Jensen and his neighbours quickly discovered, were irreversibly locked. Restarting only returned them to the same black screen.

All across Maersk headquarters, the full scale of the crisis was starting to become clear. Within half an hour, Maersk employees were running down hallways, yelling to their colleagues to turn off computers or disconnect them from Maersk’s network before the malicious software could infect them, as it dawned on them that every minute could mean dozens or hundreds more corrupted PCs. Tech workers ran into conference rooms and unplugged machines in the middle of meetings. Soon staffers were hurdling over locked key-card gates, which had been paralyzed by the still-mysterious malware to spread the warning to other sections of the building.

Disconnecting Maersk’s entire global network took the company’s IT staff more than two panicky hours. By the end of that process, every employee had been ordered to turn off their computer and leave it at their desk. The digital phones at every cubicle, too, had been rendered useless in the emergency network shutdown.

Around 3 pm, a Maersk executive walked into the room where Jensen and a dozen or so of his colleagues were anxiously awaiting news and told them to go home. Maersk’s network was so deeply corrupted that even IT staffers were helpless. A few of the company’s more old-school managers told their teams to remain at the office. But many employees were rendered entirely idle without computers, servers, routers, or desk phones and simply left.

Jensen walked out of the building and into the warm air of a late June afternoon. Like the vast majority of Maersk staffers, he had no idea when he might return to work.

On the edge of the trendy Podil neighbourhood in the Ukrainian capital of Kiev, coffee shops and parks abruptly evaporate, replaced by a grim industrial landscape. Under a highway overpass, across some trash-strewn railroad tracks, and through a concrete gate stands the four-story headquarters of Linkos Group, a small, family-run Ukrainian software business.

Up three flights of stairs in that building is a server room, where a rack of ­pizza-box-sized computers is connected by a tangle of wires and marked with handwritten, numbered labels. On a normal day, these servers push out routine updates—bug fixes, security patches, new features—to a piece of accounting software called M.E.Doc, which is more or less Ukraine’s equivalent of MYOB or Quickbooks. It’s used by nearly anyone who files taxes or does business in the country.

But for a moment in 2017, those machines served as ground zero for the most devastating cyberattack since the invention of the internet—an attack that began, at least, as an assault on one nation by another. For the past four and a half years, Ukraine has been locked in a grinding, undeclared war with Russia that has killed more than 10,000 Ukrainians and displaced millions more. The conflict has also seen Ukraine become scorched earth battleground for Russian cyberwar tactics. In 2015 and 2016, while the Kremlin-linked hackers known as Fancy Bear were busy breaking into the US Democratic National Committee’s servers, another group of agents known as Sandworm was hacking into dozens of Ukrainian governmental organisations and companies. They penetrated the networks of victims ranging from media outlets to railway firms, detonating logic bombs that destroyed terabytes of data. The attacks followed a sadistic seasonal cadence. In the winters of both years, the saboteurs capped off their destructive sprees by causing widespread power outages—the first confirmed blackouts induced by hackers.

But those attacks still weren’t Sandworm’s grand finale. In the spring of 2017, unbeknownst to anyone at Linkos Group, Russian military hackers hijacked the company’s update servers to allow them a hidden backdoor into the thousands of PCs around the country and the world that have M.E.Doc installed. Then, in June 2017, the saboteurs used that back door to release a piece of malware called NotPetya.

The code that the hackers pushed out was honed to spread automatically, rapidly, and indiscriminately. “To date, it was simply the fastest-propagating piece of malware we’ve ever seen,” says Craig Williams, director of outreach at Cisco’s Talos division, one of the first security companies to reverse engineer and analyze Not­Petya. “By the second you saw it, your data centre was already gone.”

NotPetya was propelled by two powerful hacker exploits working in tandem: One was a penetration tool known as EternalBlue, created by the US National Security Agency but leaked in a disastrous breach of the agency’s ultrasecret files earlier in 2017. EternalBlue takes advantage of a vulnerability in a particular Windows protocol, allowing hackers free rein to remotely run their own code on any unpatched machine.

NotPetya’s architects combined that digital skeleton key with an older invention known as Mimikatz, created as a proof of concept by French security researcher Benjamin Delpy in 2011. Delpy had originally released Mimikatz to demonstrate that Windows left users’ passwords lingering in computers’ memory. Once hackers gained initial access to a computer, Mimikatz could pull those passwords out of RAM and use them to hack into other machines accessible with the same credentials. On networks with multiuser computers, it could even allow an automated attack to hopscotch from one machine to the next.

Before NotPetya’s launch, Microsoft had released a patch for its EternalBlue vulnerability. But EternalBlue and Mimikatz together nonetheless made a virulent combination. “You can infect computers that aren’t patched, and then you can grab the passwords from those computers to infect other computers that are patched,” Delpy says.

The release of NotPetya was an act of cyberwarfare by almost any definition, one that was likely more explosive than even its creators intended. Within hours of its first appearance, the worm raced beyond Ukraine and out to countless machines around the world, from hospitals in Pennsylvania to a chocolate factory in Tasmania. It ­crippled multinational companies including Maersk, pharmaceutical giant Merck, FedEx’s European subsidiary TNT Express, French construction company Saint-Gobain, food producer Mondelēz, and manufacturer Reckitt Benckiser. In each case, it inflicted nine-figure costs. It even spread back to Russia, striking the state oil company Rosneft.