What is the most sophisticated piece of software/code ever written?

Buckle in.

The most sophisticated software in history was written by a team of people whose names we do not know.

It’s a computer worm. The worm was written, probably, between 2005 and 2010.

Because the worm is so complex and sophisticated, I can only give the most superficial outline of what it does.

This worm exists first on a USB drive. Someone could just find that USB drive lying around, or get it in the mail, and wonder what was on it. When that USB drive is inserted into a Windows PC, without the user knowing it, that worm will quietly run itself, and copy itself to that PC. It has at least three ways of trying to get itself to run. If one way doesn’t work, it tries another. At least two of these methods to launch itself were completely new then, and both of them used two independent, secret bugs in Windows that no one else knew about, until this worm came along.

Once the worm runs itself on a PC, it tries to get administrator access on that PC. It doesn’t mind if there’s antivirus software installed — the worm can sneak around most antivirus software. Then, based on the version of Windows it’s running on, the worm will try one of two previously unknown methods of getting that administrator access on that PC. Until this worm was released, no one knew about these secret bugs in Windows either.

At this point, the worm is now able to cover its tracks by getting underneath the operating system, so that no antivirus software can detect that it exists. It binds itself secretly to that PC, so that even if you look on the disk for where the worm should be, you will see nothing. This worm hides so well, that the worm ran around the Internet for over a year without any security company in the world recognizing that it even existed.

The software then checks to see if it can get on the Internet. If it can, it attempts to visit either http://www.mypremierfutbol.com or http://www.todaysfutbol.com . At the time, these servers were in Malaysia and Denmark. It opens an encrypted link and tells these servers that it has succeeded in owning a new PC. The worm then automatically updates itself with the newest version.

At this point, the worm makes copies of itself to any other USB sticks you happen to plug in. It does this by installing a carefully designed but fake disk driver. This driver was digitally signed by Realtek, which means that the authors of the worm were somehow able to break into the most secure location in a huge Taiwanese company, and steal the most secret key that this company owns, without Realtek finding out about it.

Later, whoever wrote that driver started signing it with secret keys from JMicron, another big Taiwanese company. Yet again, the authors had to figure out how to break into the most secure location in that company and steal the most secure key that that company owns, without JMicron finding out about it.

This worm we are talking about is sophisticated.

And it hasn’t even got started yet.

At this point, the worm makes use of two recently discovered Windows bugs. One bug relates to network printers, and the other relates to network files. The worm uses those bugs to install itself across the local network, onto all the other computers in the facility.

Now, the worm looks around for a very specific bit of control software, designed by Siemens for automating large industrial machinery. Once it finds it, it uses (you guessed it) yet another previously unknown bug for copying itself into the programmable logic of the industrial controller. Once the worm digs into this controller, it’s in there for good. No amount of replacing or disinfecting PCs can get rid of the worm now.

The worm checks for attached industrial electric motors from two specific companies. One of those companies is in Iran, and the other is in Finland. The specific motors it searches for are called variable-frequency drives. They’re used for running industrial centrifuges. You can purify many kinds of chemicals in centrifuges.

Such as uranium.

Now at this point, since the worm has complete control of the centrifuges, it can do anything it wants with them. The worm can shut them all down. The worm can destroy them all immediately — just spin them over maximum speed until they all shatter like bombs, killing anyone who happens to be standing near.

But no. This is a sophisticated worm. The worm has other plans.

Once it controls every centrifuge in your facility… the worm just goes to sleep.

Days pass. Or weeks. Or seconds.

When the worm decides the time is right, the worm quietly wakes itself up. The worm randomly picks a few of those centrifuges while they are purifying uranium. The worm locks them, so that if someone notices that something is wrong, a human can’t turn the centrifuges off.

And then, stealthily, the worm starts spinning those centrifuges… a little wrong. Not a crazy amount wrong, mind you. Just, y’know, a little too fast. Or a little too slow. Just a tiny bit out of safe parameters.

At the same time, it increases the gas pressure in those centrifuges. The gas in those centrifuges is called UF6. Pretty nasty stuff. The worm makes the pressure of that UF6, just a tiny bit out of safe parameters. Just enough that the UF6 gas in the centrifuges, has a small chance of turning into rock, while the centrifuge is spinning.

Centrifuges don’t like running too fast or too slow. And they don’t like rocks either.

The worm has one last trick up its sleeve. And it’s pure evil genius.

In addition to everything else it’s doing, the worm is now playing us back a 21-second data recording on our computer screens that it captured when the centrifuges were working normally.

The worm plays the recording over and over, in a loop.

As a result, all the centrifuge data on the computer screens looks completely fine, to us humans.

But it’s all just a fake recording, produced by the worm.

Now let’s imagine that you are responsible for purifying uranium using this huge industrial factory. And everything seems to be working okay. Maybe some of the motors sound a little off, but all the numbers on the computer show that the centrifuge motors are running exactly as designed.

Then the centrifuges start breaking. Randomly, one after another. Usually they die quietly. Rarely though, they make a scene when they die. And the uranium yield, it keeps plummeting. Uranium has to be pure. Your uranium is not pure enough to do anything useful.

What would you do, if you were running that uranium enrichment facility? You’d check everything over and over and over, not understanding why everything was off. You could replace every single PC in your facility if you wanted to.

But the centrifuges would go right on breaking. And you have no possible way of knowing why.

And on your watch, eventually, about 1000 centrifuges would fail or be taken offline. You’d go a little crazy, trying to figure out why nothing was working as designed.

That is exactly what happened.

You would never expect that all those problems were caused by a computer worm, the most devious and intelligent computer worm in history, written by some incredibly secret team with unlimited money and unlimited resources, designed with exactly one purpose in mind: to sneak past every known digital defense, and to destroy your country’s nuclear bomb program, all without getting caught.

To have one piece of software do any ONE of those things would be a small miracle. To have it do ALL of those things and many more, well…

… the Stuxnet worm would have to be the most sophisticated software ever written.

Sources here, here, and here.

EDIT: this article I wrote is awesome. Share it, people.

I can only infer the answer, because I haven’t seen the actual code. But I’ve seen the binary file format specifications:

Early versions of Microsoft Word.

Word, designed by the brilliant Microsoft chief software architect Charles Simonyi, was a “piece table” editor, and was one of the first programs that made edits on the original text by creating a “virtual document” — the changed document never existed until it was saved back out to disk.

And once it was save our to disk, it might also exist in non-linear pieces, in what Microsoft used to refer to as their “fast save” file format. Essentially, appending pieces of text (the edits) to the end of the document.

The piece table concept was a big part of how Word could manage thousands of undoable and redoable edits.

This file format was no RTF or XML file format: it was a mixture of text and binary, and not easily understood from the outside looking in.

When I wrote the original versions of Scriptor (the first screenplay word processor), I wanted to process Word’s native binary format. This was BEFORE Microsoft published the specifications. I was far from an accomplished hacker, but I was able to not only decode and read Word documents but also WRITE new Word documents. I believe I may have been the first person outside Microsoft to do so. This caught the attention of the Word Program Manager, who kindly decided to send me some rudimentary internal documentation of the actual file format.

What I read astonished me: there was (for 1985) an unbelievable level of sophistication to Word’s binary file format. To some extent the format specification was self-documenting, because the identifiers (variables and functions) used Charles Simonyi’s “Hungarian” variable-naming notation (see https://en.m.wikipedia.org/wiki/...). But because of the Hungarian notation, it was opaque and difficult to grok.

Early versions of Word were also based on an interpretive programming language, or P-code. This allowed Word’s complex feature set to be ported between Mac, DOS, and Windows, at the expense of performance.

An outsider unable to use Word’s internal code to access the binary file format might see its elegant sophistication as great complexity, which led to this warning to me from the Word Program Manager:

“Steve — if you continue to support Word’s binary file format, you’ll be going down a path of endless pain.”

Those haunting words — and my glimse into Word’s file format — left a lasting impression of a level of software design sophistication I hadn’t seen before — or since.

Sophisticated, meaning not necessarily complex, nor even the most obvious> So, become familiar with PROMIS: a software so coveted that people were murdered, governmnets stole it; it became one of the longest running conspiracies in American history (next to the JFK assassination) and it still, today, runs on the backdoors of major financial institutions, intelligence agencies, and was weaponized to target Iranian nuclear projects.

This was the INSLAW scandal, centered around a SOPHISTICATED database program:

“…The program, dubbed the Prosecutor’s Management Information System (PROMIS), was effective and popular. It allowed a prosecutor to locate defendants and witnesses, track motions and monitor ongoing investigations. In 1982, Inslaw won a large Justice Department contract to implement the system nationwide.

In the meantime, Inslaw also developed privately owned enhancements to PROMIS. Despite contractural guarantees of Inslaw’s proprietary rights to the enhanced version of PROMIS, the Justice Department essentially commandeered the improved program for its own uses without paying for it. Inslaw was forced into bankruptcy and began an endless fight with the Justice Department to recoup its losses.

In the course of their court battles, Inslaw founder Bill Hamilton and his wife innocently stumbled upon shocking national security revelations. Former Attorney General Ed Meese, the Hamiltons concluded, had conspired to force Inslaw into bankruptcy so that an old Meese crony, California businessman Earl Brian, could take over the company’s assets. The Hamilton’s obtained information through sworn affidavits of several individuals that suggested Meese, Brian, high-ranking Justice Department official Peter Videnieke and others wanted to modify and distribute the enhanced PROMIS software with ‘back-door’ capabilities for covert intelligence operations.” from America’s Spy Software Scandal,Courtesy of the U.S. DOJ

The Last Circle: Danny Casolaro's Investigation into the Octopus and the PROMIS Software Scandal by Cheri Seymour

Probing one of most organized and complex criminal enterprises in the United States, this report exposes the dynamics of the Octopus, a globe-trotting undercover intelligence operative. Based on 18 years of investigative research, this account reveals high-level, covert government operations and the elaborate corporate structures and the theft of high-tech software (PROMIS) used as smoke-and-mirror covers for narcotics trafficking, money laundering, arms sales, and espionage. The Octopus connections to a maze of politicians and officials in the National Security Council, the CIA, the FBI, and the U.S. Department of Justice are revealed. A detailed look into the recent high-profile arrest of Mafia hit-man Jimmy Hughes is also included in this intriguing analysis.

At 12:30 pm on August 10, 1991, forty-four-year-old investigative reporter Danny Casolaro was found dead in his hotel room near Martinsburg, West Virginia. A maid had found him in his bathtub. Both of his wrists had been slashed several times. Police were called in to investigate.

His family and many others are convinced that Danny's investigation into INSLAW and the Justice Department led to his death.
Several people believe Danny was murdered by a secret clandestine government agency dubbed "The Octopus," but such a presence is unconfirmed at best. His family believes that the group killed him because he learned too much during his investigation of Inslaw and the U.S. Justice Department.

According to PJ Wilcox, author of the World Security Network:"The malware worm (Stuxnet) may have started out as a logistical program, Promis. Then it morphed into an “Enhanced Promis” for intelligence work. It was subsequently altered for specific situations, given different names and sold to perhaps a dozen countries, worming its way around the world. In the process, rather than burrowing, the worm became like a centipede with hundreds of legs regenerating in different sizes and shapes, taking direction from its owners regarding objectives."

In this respondent’s opinion: THE most sophisticated software ever written…and it appears to continue to run to this very day!

We have no idea, because most software is closed-source and so we cannot analyse it. If we have to pick something we can actually argue about, we are restricted to open-source software.

In this realm, surely the Linux kernel is a strong contender. It does not “run on” anything, it *makes* almost everything run from tiny computers like the raspberry pi to smartphones to huge mainframes. Contrary to some of the answers here that list software that somewhat confidential or even downright speculative in their implementation, the Linux kernel runs everywhere. If you are reading this, chances are you are running some version of the Linux kernel in your daily life, and you don’t even realise it.

Unobtrusive, pervasive, reliable, free and libre, useful. This is one hell of a sophisticated piece of software and a fantastic achievement.

For my generation(80’s), the greatest software written by one person is Jonathon Sachs (co-founder of Lotus 1–2–3) who wrote an application that had a spreadsheets, graphics, and a database in 1983 when memory was just 640K.

He wrote this in 8088 Assembler and went around the BIOS and DOS to access hardware directly which made it very fast. You can still download Version 1.0A for free

The most sophisticated piece of software/code ever written would be the software that runs on the most sophisticated computer ever created. It was actually created by another computer and you’ve actually taken part in the project, perhaps without even knowing about it!

You can read all about this in Douglas Adams’ Hittchhiker’s Guide to the Galaxy but I’ll give you a quick summary here.

• A computer was created to calculate the answer to the ultimate question of life, the universe and everything. They called this computer “Deep Thought.”
• After many, many years of calculation (seven million years, to be exact) it gave them the answer: 42
• The computer insisted that this was the correct answer. The problem was that they didn’t understand the question!
• Deep Thought designed another computer, better than itself, to tell them what the question is.
• They named the new computer “Earth.”
• The new computer and its accompanying software would take four-and-a-half billion years to calculate the answer, err… question.
• Fifteen minutes before the calculation is complete, the Earth will be destroyed.

So the most sophisticated software/code ever written is the software that runs the Earth.

You didn’t specify whether or not it could be fictional and since everybody who works with computers should know about the Hitchhiker’s Guide and Monty Python I figured I work on half of that here.