The Enemy Within

THE FIRST SURPRISING thing about the worm that landed in Philip Porras’s digital petri dish 18 months ago was how fast it grew.

He first spotted it on Thursday, November 20, 2008. Computer-security experts around the world who didn’t take notice of it that first day soon did. Porras is part of a loose community of high-level geeks who guard computer systems and monitor the health of the Internet by maintaining “honeypots,” unprotected computers irresistible to “malware,” or malicious software. A honeypot is either a real computer or a virtual one within a larger computer designed to snare malware. There are also “honeynets,” which are networks of honeypots. A worm is a cunningly efficient little packet of data in computer code, designed to slip inside a computer and set up shop without attracting attention, and to do what this one was so good at: replicate itself.

Most of what honeypots snare is routine, the viral annoyances that have bedeviled computer-users everywhere for the past 15 years or so, illustrating the principle that any new tool, no matter how useful to humankind, will eventually be used for harm. Viruses are responsible for such things as the spamming of your inbox with penis-enlargement come-ons or million-dollar investment opportunities in Nigeria. Some malware is designed to damage or destroy your computer, so once you get the infection, you quickly know it. More-sophisticated computer viruses, like the most successful biological viruses, and like this new worm, are designed for stealth. Only the most technically capable and vigilant computer-operators would ever notice that one had checked in.

Porras, who operates a large honeynet for SRI International in Menlo Park, California, noted the initial infection, and then an immediate reinfection. Then another and another and another. The worm, once nestled inside a computer, began automatically scanning for new computers to invade, so it spread exponentially. It exploited a flaw in Microsoft Windows, particularly Windows 2000, Windows XP, and Windows Server 2003—some of the most common operating systems in the world—so it readily found new hosts. As the volume increased, the rate of repeat infections in Porras’s honeynet accelerated. Within hours, duplicates of the worm were crowding in so rapidly that they began to push all the other malware, the ordinary daily fare, out of the way. If the typical inflow is like a stream from a faucet, this new strain seemed shot out of a fire hose. It came from computer addresses all over the world. Soon Porras began to hear from others in his field who were seeing the same thing. Given the instant and omnidirectional nature of the Internet, no one could tell where the worm had originated. Overnight, it was everywhere. And on closer inspection, it became clear that voracity was just the first of its remarkable traits.

Various labs assigned names to the worm. It was dubbed “Downadup” and “Kido,” but the name that stuck was “Conficker,” which it was given after it tried to contact a fake security Web site, Microsoft security programmers shuffled the letters and came up with Conficker, which stuck partly because ficker is German slang for “motherfucker,” and the worm was certainly that. At the same time that Conficker was spewing into honeypots, it was quietly slipping into personal computers worldwide—an estimated 500,000 in the first month.

Why? What was its purpose? What was it telling all those computers to do?

Imagine your computer to be a big spaceship, like the starship Enterprise on Star Trek. The ship is so complex and sophisticated that even an experienced commander like Captain James T. Kirk has only a general sense of how every facet of it works. From his wide swivel chair on the bridge, he can order it to fly, maneuver, and fight, but he cannot fully comprehend all its inner workings. The ship contains many complex, interrelated systems, each with its own function and history—systems for, say, guidance, maneuvers, power, air and water, communications, temperature control, weapons, defensive measures, etc. Each system has its own operator, performing routine maintenance, exchanging information, making fine adjustments, keeping it running or ready. When idling or cruising, the ship essentially runs itself without a word from Captain Kirk. It obeys when he issues a command, and then returns to its latent mode, busily doing its own thing until the next time it is needed.

Now imagine a clever invader, an enemy infiltrator, who does understand the inner workings of the ship. He knows it well enough to find a portal with a broken lock overlooked by the ship’s otherwise vigilant defenses—like, say, a flaw in Microsoft’s operating platform. So no one notices when he slips in. He trips no alarm, and then, to prevent another clever invader from exploiting the same weakness, he repairs the broken lock and seals the portal shut behind him. He improves the ship’s defenses. Ensconced securely inside, he silently sets himself up as the ship’s alternate commander. He enlists the various operating functions of the ship to do his bidding, careful to avoid tripping any alarms. Captain Kirk is still up on the bridge in his swivel chair with the magnificent instrument arrays, unaware that he now has a rival in the depths of his ship. The Enterprise continues to perform as it always has. Meanwhile, the invader begins surreptitiously communicating with his own distant commander, letting him know that he is in position and ready, waiting for instructions.

And now imagine a vast fleet, in which the Enterprise is only one ship among millions, all of them infiltrated in exactly the same way, each ship with its hidden pilot, ever alert to an outside command. In the real world, this infiltrated fleet is called a “botnet,” a network of infected, “robot” computers. The first job of a worm like Conficker is to infect and link together as many computers as possible—the phenomenon witnessed by Porras and other security geeks in their honeypots. Thousands of botnets exist, most of them relatively small—a few thousand or a few tens of thousands of infected computers. More than a billion computers are in use around the world, and by some estimates, a fourth of them have been surreptitiously linked to a botnet. But few botnets approach the size and menace of the one created by Conficker, which has stealthily linked between 6 million and 7 million computers.

Once created, botnets are valuable tools for criminal enterprise. Among other things, they can be used to efficiently distribute malware, to steal private information from otherwise secure Web sites or computers, to assist in fraudulent schemes, or to launch denial-of-service attacks—overwhelming a target computer with a flood of requests for response. The creator of an effective botnet, one with a wide range and the staying power to defeat security measures, can use it himself for one of the above scams, or he can sell or lease it to people who specialize in exploiting botnets. (Botnets can be bought or leased in underground markets online.)

Beyond criminal enterprise, botnets are also potentially dangerous weapons. If the right order were given, and all these computers worked together in one concerted effort, a botnet with that much computing power could crack many codes, break into and plunder just about any protected database in the world, and potentially hobble or even destroy almost any computer network, including those that make up a country’s vital modern infrastructure: systems that control banking, telephones, energy flow, air traffic, health-care information—even the Internet itself.

The key word there is could, because so far Conficker has done none of those things. It has been activated only once, to perform a relatively mundane spamming operation—enough to demonstrate that it is not benign. No one knows who created it. No one yet fully understands how it works. No one knows how to stop it or kill it. And no one even knows for sure why it exists.

If yours is one of the infected machines, you are like Captain Kirk, seemingly in full command of your ship, unaware that you have a hidden rival, or that you are part of this vast robot fleet. The worm inside your machine is not idle. It is stealthily running, issuing small maintenance commands, working to protect itself from being discovered and removed, biding its time, and periodically checking in with its command-and-control center. Conficker has taken over a large part of our digital world, and so far most people haven’t even noticed.

The struggle against this remarkable worm is a sort of chess match unfolding in the esoteric world of computer security. It pits the cleverest attackers in the world, the bad guys, against the cleverest defenders in the world, the good guys (who have been dubbed the “Conficker Cabal”). It has prompted the first truly concerted global effort to kill a computer virus, extraordinary feats of international cooperation, and the deployment of state-of-the-art decryption techniques—moves and countermoves at the highest level of programming. The good guys have gone to unprecedented lengths, and have had successes beyond anything they would have thought possible when they started. But a year and a half into the battle, here’s the bottom line:

The worm is winning.

A Digital Sam Spade
Twenty years ago, computers were bedeviled by hackers. These were savvy outlaws who used their deep knowledge of operating systems to invade, steal, and destroy, or sometimes just to tap into secure facilities and show off their skills. Hackers became heroes to a generation of teenagers, and had all sorts of motives, but their most distinctive trait was a tendency to show off.

Some had truly malicious intent. In his 1989 best seller, The Cuckoo’s Egg, Cliff Stoll told the story of his stubborn, virtually single-handed hunt for an elusive hacker in Germany who was using Stoll’s computer system at the Lawrence Berkeley National Laboratory as a portal to Defense Department computers. For many people, Stoll’s book was the introduction to the netherworld of rarefied gamesmanship that defines computer security. Stoll’s hacker never penetrated the most secret corners of the national-security net, and even relatively serious breaches like the one Stoll described were more nuisance than threat. But the individual hacker working as a spy or vandal has evolved into something more organized and menacing.

Andre’ M. DiMino, a computer sleuth who is part of the Conficker Cabal, is considered one of the world’s foremost authorities on botnets. He stumbled into his avocation on a Monday morning a decade ago, when he discovered that over the weekend, someone had broken into the computer system he was administering for a small company in New Jersey. DiMino has an undergraduate degree in electrical engineering with an emphasis in computer science, but he has mostly taught himself up to his present level of expertise, which is extreme. At 45, he is a slender, affable idealist who keeps a small array of computers in an upstairs bedroom. When I stopped by to talk to him, he baked me pizza. His day job is doing computer forensics for law enforcement in Bergen County, New Jersey, but he has a kind of alter ego as what he calls a “botnet hunter.”

Back when he discovered the weekend break-in, DiMino assumed at first that it was the work of a hacker, a vandal, or possibly a former employee, only to discover, based on an analysis of the IP (Internet Protocol) addresses of the incoming data, that his little computer network had been invaded by someone from Turkey or Ukraine. What would someone halfway around the planet want with the computer system of a small business-management firm in a New Jersey office park? Apparently, judging by what he found, his invader was in the business of selling pirated software, movies, and music. Needing large amounts of digital storage space to hide stolen inventory, the culprit seemed to have conducted an automated search over the Internet, looking worldwide for vulnerable systems with large amounts of unused disc space—DiMino equates it to walking around rattling doorknobs, looking for one door left unlocked. DiMino’s system fit the bill, so the crooks had dumped a huge bloc of data onto his discs. He erased the stash and locked the door that had allowed the pirates in. As far as the company was concerned, that solved the problem. No harm done. No need to call the police or investigate further.

But DiMino was intrigued. He reviewed the server logs for previous weeks and saw that this successful invasion was one of many such efforts. Other attackers had been rattling the doors of his network, looking for vulnerabilities. If there were bad guys actively exploiting other people’s computers all over the world, designing sophisticated programs to exploit weaknesses … how cool was that? And who was trying to stop them?

DiMino set about educating himself on the fine points of this obscure battle of wits. He eventually co-founded the Shadowserver Foundation, a nonprofit partnership of defense-minded geeks at war with malware, effectively transforming himself into a digital Sam Spade—indeed, the graphic atop Shadowserver’s home page features a Dashiell Hammett–style detective emerging from shadow.

Both sides in this cyberwar have become astonishingly sophisticated, operating at the cutting edge of programming theory and cryptography. Both understand the limits of security methodology, the one side working to broaden its reach, the other working to surpass it. Because malware has been automated, the good guys usually can only guess at who they are up against.

Trojans, Viruses, and Worms
Rodney Joffe heads the cabal that has been battling Conficker. He is a burly, garrulous South African–born American who serves as senior vice president and chief technologist for Neustar, a company that provides trunk-line service for competing cell-phone companies around the world. Joffe’s interest in stopping the worm did not stem just from his outrage and sense of justice. His concern for Neustar’s operation is professional, and illustrative.

The company runs a huge local-number-portability database. Almost every phone call in North America, before it’s completed, must ask Neustar where to go. Back in the old days, when the phone company was a monopoly, telecommunications were relatively simple. You could figure out where a phone call was going, right down to the building where the target phone would ring, just by looking at the number. Today we have competing telephone companies, and cell phones, and a person’s telephone number is no longer necessarily tied to a geographic location. In this more complex world, someone needs to keep track of every single phone number, and know where to route calls so they end up in the right place. Neustar performs this service for telephone calls, and is one of many registries that oversee high-level Internet domains. It is, in Joffe’s words, “the map.”

“If I disappear, there’s no map,” he says. “So if you take us down, whole countries can actually disappear from the grid. They’re connected, but no one can find their way there, because the map’s disappeared.”

A botnet like Conficker could theoretically be used to shut down Neustar’s system. So Joffe helped form the Conficker Cabal. He scoffed when he read in late 2009 that the Obama administration’s Department of Homeland Security planned to hire “a thousand” computer-security experts over the next three years. “There aren’t more than a few hundred people in the world who understand this stuff.”

Most of us use the word virus to describe all malware, but in geekspeak, it means something more specific. There are three types of the stuff: Trojans, viruses, and worms. A Trojan is a piece of software that works like a Trojan horse, masquerading as one thing to get inside a computer, and then attacking. A virus attacks the host computer after slipping in through a hole in its operating system. It depends on the computer-operator—you—doing something stupid to activate it, like opening an attachment to an e-mail that appears innocuous, or clicking on an enticing link. A worm works like a virus, exploiting flaws in operating systems, but it doesn’t attack once it breaks in. It generally doesn’t have a malicious payload. Exactly like the most-sophisticated viruses in the biological world, it does not cripple or kill its host. It is primarily designed to spread. The instructions that will put a worm like Conficker to work are not embedded in its code; they will be delivered later, from a remote command center.

In the old days, when your computer got infected, it slowed down because your commands had to compete for processing with viral invaders. You knew something was wrong because the machine took 10 times longer to boot up, or there was a delay between command and response. You began to get annoying pop-ups on your screen directing you to download supposedly remedial software. Programs would freeze. In this sense, the old malware was like the Ebola virus, a very scary strain that messily kills nearly everyone it infects—which is another way of saying that it is grossly ineffective, because it burns out the very host organisms it needs to survive. The miscreants who created computer viruses years ago learned that malware that announces itself in these ways doesn’t last.

So today’s malware produces no pop-ups, no slowdowns. A worm is especially quiet, since all it does, at least initially, is spread. Conficker stealthily sets up shop without making a ripple, and—other than calling home periodically for instructions—just waits. Its regular messages to its command center amount to only a couple hundred bytes of data, which is not enough to even light up the little bulb that flashes when a computer hard drive is at work.

After Phil Porras and others began snaring Conficker in increasing numbers, they began dissecting it. The worm itself was exquisite. It consisted of only a few hundred lines of code, no more than 35 kilobytes—slightly smaller than a 2,000-word document. In comparison, the average home computer today has anywhere from 40 to 200 gigabytes of storage. Unless you were looking for it, unless you knew how to look for it, you would never see it. Conficker drifts in like a mote.

It exploited a specific hole, Port 445, in the Microsoft operating systems, a vulnerability that the manufacturer had tried to repair just weeks earlier. Ports are designated “listening” points in a system, designed to transmit and receive particular kinds of data. There are many of them, more than 65,000, because an operating system consists of layer upon layer of functions. A firewall is a security program that guards these ports, controlling the flow of data in and out. Some ports, like the one that handles e-mail, are heavily trafficked. Most are not; they listen for updates and instructions that deal with a narrow and specific function, usually routine procedures that never rise to the notice of computer-users. Only certain very specific kinds of data can flow through ports, and then only with the appropriate codes. Windows opens Port 445 by default to perform tasks like issuing instructions for print-sharing or file-sharing. Late in the summer of 2008, Microsoft learned that even a system protected by a firewall was vulnerable at Port 445 if print-sharing and file-sharing were enabled (which they were on many computers). In other words, even a well-protected computer had a hole. On October 23, 2008, the company issued a rare “critical security bulletin” (MS08-067) with a patch to repair that hole. A specially crafted “remote procedure call” could allow the port to be used by a remote operator, the security bulletin warned, and “an attacker could exploit this vulnerability without authentication to run arbitrary code.” The patch Microsoft offered theoretically slammed the door on a worm like Conficker almost a month before it appeared.


In fact, the bulletin itself may have inspired the creation of Conficker. Many, many computer-operators worldwide—you know who you are—fail to diligently heed security updates. And the patches are issued only to computers with validated software installations; millions of computers run on bootlegged operating systems, which have never been validated. Microsoft issues its updates on the second Tuesday of every month. Every geek in the world knows this; it’s called “Patch Tuesday.” The company employs some of the best programmers in the world to stay one step ahead of the bad guys. If everyone applied the new patches promptly, Windows would be nigh impregnable. But because so many people fail to apply the patches promptly, and because so many machines run on illegitimate Windows systems, Patch Tuesday has become part of Microsoft’s problem. The company points out its own vulnerabilities, which is like a general responsible for defending a fort making a public announcement—“The back door to the supply shed in the southeast corner of the garrison has a broken lock; here’s how to fix it.” When there is only one fort, and it is well policed, the lock is fixed and the vulnerability disappears. But when you are defending millions of forts, and a goodly number of the people responsible for their security snooze right through Patch Tuesday, the security bulletin doesn’t just invite attack, it provides a map! Twenty-eight days after the MS08-067 security bulletin appeared, Conficker started worming its way into unpatched computers.