Entries Tagged "patching"

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Measuring Vulnerability Rediscovery

New paper: “Taking Stock: Estimating Vulnerability Rediscovery,” by Trey Herr, Bruce Schneier, and Christopher Morris:

Abstract: How often do multiple, independent, parties discover the same vulnerability? There are ample models of vulnerability discovery, but little academic work on this issue of rediscovery. The immature state of this research and subsequent debate is a problem for the policy community, where the government’s decision to disclose a given vulnerability hinges in part on that vulnerability’s likelihood of being discovered and used maliciously by another party. Research into the behavior of malicious software markets and the efficacy of bug bounty programs would similarly benefit from an accurate baseline estimate for how often vulnerabilities are discovered by multiple independent parties.

This paper presents a new dataset of more than 4,300 vulnerabilities, and estimates vulnerability rediscovery across different vendors and software types. It concludes that rediscovery happens more than twice as often as the 1-9% range previously reported. For our dataset, 15% to 20% of vulnerabilities are discovered independently at least twice within a year. For just Android, 13.9% of vulnerabilities are rediscovered within 60 days, rising to 20% within 90 days, and above 21% within 120 days. For the Chrome browser we found 12.57% rediscovery within 60 days; and the aggregate rate for our entire dataset generally rises over the eight-year span, topping out at 19.6% in 2016. We believe that the actual rate is even higher for certain types of software.

When combined with an estimate of the total count of vulnerabilities in use by the NSA, these rates suggest that rediscovery of vulnerabilities kept secret by the U.S. government may be the source of up to one-third of all zero-day vulnerabilities detected in use each year. These results indicate that the information security community needs to map the impact of rediscovery on the efficacy of bug bounty programs and policymakers should more rigorously evaluate the costs of non-disclosure of software vulnerabilities.

We wrote a blog post on the paper, and another when we issued a revised version.

Comments on the original paper by Dave Aitel. News articles.

Posted on July 31, 2017 at 5:59 AMView Comments

Zero-Day Vulnerabilities against Windows in the NSA Tools Released by the Shadow Brokers

In April, the Shadow Brokers — presumably Russia — released a batch of Windows exploits from what is presumably the NSA. Included in that release were eight different Windows vulnerabilities. Given a presumed theft date of the data as sometime between 2012 and 2013 — based on timestamps of the documents and the limited Windows 8 support of the tools:

  • Three were already patched by Microsoft. That is, they were not zero days, and could only be used against unpatched targets. They are EMERALDTHREAD, EDUCATEDSCHOLAR, and ECLIPSEDWING.
  • One was discovered to have been used in the wild and patched in 2014: ESKIMOROLL.
  • Four were only patched when the NSA informed Microsoft about them in early 2017: ETERNALBLUE, ETERNALSYNERGY, ETERNALROMANCE, and ETERNALCHAMPION.

So of the five serious zero-day vulnerabilities against Windows in the NSA’s pocket, four were never independently discovered. This isn’t new news, but I haven’t seen this summary before.

Posted on July 28, 2017 at 6:16 AMView Comments

Good Article About Google's Project Zero

Fortune magazine just published a good article about Google’s Project Zero, which finds and publishes exploits in other companies’ software products.

I have mixed feeling about it. The project does great work, and the Internet has benefited enormously from these efforts. But as long as it is embedded inside Google, it has to deal with accusations that it targets Google competitors.

Posted on June 30, 2017 at 6:05 AMView Comments

Is Continuing to Patch Windows XP a Mistake?

Last week, Microsoft issued a security patch for Windows XP, a 16-year-old operating system that Microsoft officially no longer supports. Last month, Microsoft issued a Windows XP patch for the vulnerability used in WannaCry.

Is this a good idea? This 2014 essay argues that it’s not:

The zero-day flaw and its exploitation is unfortunate, and Microsoft is likely smarting from government calls for people to stop using Internet Explorer. The company had three ways it could respond. It could have done nothing­ — stuck to its guns, maintained that the end of support means the end of support, and encouraged people to move to a different platform. It could also have relented entirely, extended Windows XP’s support life cycle for another few years and waited for attrition to shrink Windows XP’s userbase to irrelevant levels. Or it could have claimed that this case is somehow “special,” releasing a patch while still claiming that Windows XP isn’t supported.

None of these options is perfect. A hard-line approach to the end-of-life means that there are people being exploited that Microsoft refuses to help. A complete about-turn means that Windows XP will take even longer to flush out of the market, making it a continued headache for developers and administrators alike.

But the option Microsoft took is the worst of all worlds. It undermines efforts by IT staff to ditch the ancient operating system and undermines Microsoft’s assertion that Windows XP isn’t supported, while doing nothing to meaningfully improve the security of Windows XP users. The upside? It buys those users at best a few extra days of improved security. It’s hard to say how that was possibly worth it.

This is a hard trade-off, and it’s going to get much worse with the Internet of Things. Here’s me:

The security of our computers and phones also comes from the fact that we replace them regularly. We buy new laptops every few years. We get new phones even more frequently. This isn’t true for all of the embedded IoT systems. They last for years, even decades. We might buy a new DVR every five or ten years. We replace our refrigerator every 25 years. We replace our thermostat approximately never. Already the banking industry is dealing with the security problems of Windows 95 embedded in ATMs. This same problem is going to occur all over the Internet of Things.

At least Microsoft has security engineers on staff that can write a patch for Windows XP. There will be no one able to write patches for your 16-year-old thermostat and refrigerator, even assuming those devices can accept security patches.

Posted on June 21, 2017 at 1:58 PMView Comments

WannaCry and Vulnerabilities

There is plenty of blame to go around for the WannaCry ransomware that spread throughout the Internet earlier this month, disrupting work at hospitals, factories, businesses, and universities. First, there are the writers of the malicious software, which blocks victims’ access to their computers until they pay a fee. Then there are the users who didn’t install the Windows security patch that would have prevented an attack. A small portion of the blame falls on Microsoft, which wrote the insecure code in the first place. One could certainly condemn the Shadow Brokers, a group of hackers with links to Russia who stole and published the National Security Agency attack tools that included the exploit code used in the ransomware. But before all of this, there was the NSA, which found the vulnerability years ago and decided to exploit it rather than disclose it.

All software contains bugs or errors in the code. Some of these bugs have security implications, granting an attacker unauthorized access to or control of a computer. These vulnerabilities are rampant in the software we all use. A piece of software as large and complex as Microsoft Windows will contain hundreds of them, maybe more. These vulnerabilities have obvious criminal uses that can be neutralized if patched. Modern software is patched all the time — either on a fixed schedule, such as once a month with Microsoft, or whenever required, as with the Chrome browser.

When the US government discovers a vulnerability in a piece of software, however, it decides between two competing equities. It can keep it secret and use it offensively, to gather foreign intelligence, help execute search warrants, or deliver malware. Or it can alert the software vendor and see that the vulnerability is patched, protecting the country — and, for that matter, the world — from similar attacks by foreign governments and cybercriminals. It’s an either-or choice. As former US Assistant Attorney General Jack Goldsmith has said, “Every offensive weapon is a (potential) chink in our defense — and vice versa.”

This is all well-trod ground, and in 2010 the US government put in place an interagency Vulnerabilities Equities Process (VEP) to help balance the trade-off. The details are largely secret, but a 2014 blog post by then President Barack Obama’s cybersecurity coordinator, Michael Daniel, laid out the criteria that the government uses to decide when to keep a software flaw undisclosed. The post’s contents were unsurprising, listing questions such as “How much is the vulnerable system used in the core Internet infrastructure, in other critical infrastructure systems, in the US economy, and/or in national security systems?” and “Does the vulnerability, if left unpatched, impose significant risk?” They were balanced by questions like “How badly do we need the intelligence we think we can get from exploiting the vulnerability?” Elsewhere, Daniel has noted that the US government discloses to vendors the “overwhelming majority” of the vulnerabilities that it discovers — 91 percent, according to NSA Director Michael S. Rogers.

The particular vulnerability in WannaCry is code-named EternalBlue, and it was discovered by the US government — most likely the NSA — sometime before 2014. The Washington Post reported both how useful the bug was for attack and how much the NSA worried about it being used by others. It was a reasonable concern: many of our national security and critical infrastructure systems contain the vulnerable software, which imposed significant risk if left unpatched. And yet it was left unpatched.

There’s a lot we don’t know about the VEP. The Washington Post says that the NSA used EternalBlue “for more than five years,” which implies that it was discovered after the 2010 process was put in place. It’s not clear if all vulnerabilities are given such consideration, or if bugs are periodically reviewed to determine if they should be disclosed. That said, any VEP that allows something as dangerous as EternalBlue — or the Cisco vulnerabilities that the Shadow Brokers leaked last August to remain unpatched for years isn’t serving national security very well. As a former NSA employee said, the quality of intelligence that could be gathered was “unreal.” But so was the potential damage. The NSA must avoid hoarding vulnerabilities.

Perhaps the NSA thought that no one else would discover EternalBlue. That’s another one of Daniel’s criteria: “How likely is it that someone else will discover the vulnerability?” This is often referred to as NOBUS, short for “nobody but us.” Can the NSA discover vulnerabilities that no one else will? Or are vulnerabilities discovered by one intelligence agency likely to be discovered by another, or by cybercriminals?

In the past few months, the tech community has acquired some data about this question. In one study, two colleagues from Harvard and I examined over 4,300 disclosed vulnerabilities in common software and concluded that 15 to 20 percent of them are rediscovered within a year. Separately, researchers at the Rand Corporation looked at a different and much smaller data set and concluded that fewer than six percent of vulnerabilities are rediscovered within a year. The questions the two papers ask are slightly different and the results are not directly comparable (we’ll both be discussing these results in more detail at the Black Hat Conference in July), but clearly, more research is needed.

People inside the NSA are quick to discount these studies, saying that the data don’t reflect their reality. They claim that there are entire classes of vulnerabilities the NSA uses that are not known in the research world, making rediscovery less likely. This may be true, but the evidence we have from the Shadow Brokers is that the vulnerabilities that the NSA keeps secret aren’t consistently different from those that researchers discover. And given the alarming ease with which both the NSA and CIA are having their attack tools stolen, rediscovery isn’t limited to independent security research.

But even if it is difficult to make definitive statements about vulnerability rediscovery, it is clear that vulnerabilities are plentiful. Any vulnerabilities that are discovered and used for offense should only remain secret for as short a time as possible. I have proposed six months, with the right to appeal for another six months in exceptional circumstances. The United States should satisfy its offensive requirements through a steady stream of newly discovered vulnerabilities that, when fixed, also improve the country’s defense.

The VEP needs to be reformed and strengthened as well. A report from last year by Ari Schwartz and Rob Knake, who both previously worked on cybersecurity policy at the White House National Security Council, makes some good suggestions on how to further formalize the process, increase its transparency and oversight, and ensure periodic review of the vulnerabilities that are kept secret and used for offense. This is the least we can do. A bill recently introduced in both the Senate and the House calls for this and more.

In the case of EternalBlue, the VEP did have some positive effects. When the NSA realized that the Shadow Brokers had stolen the tool, it alerted Microsoft, which released a patch in March. This prevented a true disaster when the Shadow Brokers exposed the vulnerability on the Internet. It was only unpatched systems that were susceptible to WannaCry a month later, including versions of Windows so old that Microsoft normally didn’t support them. Although the NSA must take its share of the responsibility, no matter how good the VEP is, or how many vulnerabilities the NSA reports and the vendors fix, security won’t improve unless users download and install patches, and organizations take responsibility for keeping their software and systems up to date. That is one of the important lessons to be learned from WannaCry.

This essay originally appeared in Foreign Affairs.

Posted on June 2, 2017 at 6:06 AMView Comments

The Future of Ransomware

Ransomware isn’t new, but it’s increasingly popular and profitable.

The concept is simple: Your computer gets infected with a virus that encrypts your files until you pay a ransom. It’s extortion taken to its networked extreme. The criminals provide step-by-step instructions on how to pay, sometimes even offering a help line for victims unsure how to buy bitcoin. The price is designed to be cheap enough for people to pay instead of giving up: a few hundred dollars in many cases. Those who design these systems know their market, and it’s a profitable one.

The ransomware that has affected systems in more than 150 countries recently, WannaCry, made press headlines last week, but it doesn’t seem to be more virulent or more expensive than other ransomware. This one has a particularly interesting pedigree: It’s based on a vulnerability developed by the National Security Agency that can be used against many versions of the Windows operating system. The NSA’s code was, in turn, stolen by an unknown hacker group called Shadow Brokers ­ widely believed by the security community to be the Russians ­ in 2014 and released to the public in April.

Microsoft patched the vulnerability a month earlier, presumably after being alerted by the NSA that the leak was imminent. But the vulnerability affected older versions of Windows that Microsoft no longer supports, and there are still many people and organizations that don’t regularly patch their systems. This allowed whoever wrote WannaCry ­– it could be anyone from a lone individual to an organized crime syndicate — to use it to infect computers and extort users.

The lessons for users are obvious: Keep your system patches up to date and regularly backup your data. This isn’t just good advice to defend against ransomware, but good advice in general. But it’s becoming obsolete.

Everything is becoming a computer. Your microwave is a computer that makes things hot. Your refrigerator is a computer that keeps things cold. Your car and television, the traffic lights and signals in your city and our national power grid are all computers. This is the much-hyped Internet of Things (IoT). It’s coming, and it’s coming faster than you might think. And as these devices connect to the Internet, they become vulnerable to ransomware and other computer threats.

It’s only a matter of time before people get messages on their car screens saying that the engine has been disabled and it will cost $200 in bitcoin to turn it back on. Or a similar message on their phones about their Internet-enabled door lock: Pay $100 if you want to get into your house tonight. Or pay far more if they want their embedded heart defibrillator to keep working.

This isn’t just theoretical. Researchers have already demonstrated a ransomware attack against smart thermostats, which may sound like a nuisance at first but can cause serious property damage if it’s cold enough outside. If the device under attack has no screen, you’ll get the message on the smartphone app you control it from.

Hackers don’t even have to come up with these ideas on their own; the government agencies whose code was stolen were already doing it. One of the leaked CIA attack tools targets Internet-enabled Samsung smart televisions.

Even worse, the usual solutions won’t work with these embedded systems. You have no way to back up your refrigerator’s software, and it’s unclear whether that solution would even work if an attack targets the functionality of the device rather than its stored data.

These devices will be around for a long time. Unlike our phones and computers, which we replace every few years, cars are expected to last at least a decade. We want our appliances to run for 20 years or more, our thermostats even longer.

What happens when the company that made our smart washing machine — or just the computer part — goes out of business, or otherwise decides that they can no longer support older models? WannaCry affected Windows versions as far back as XP, a version that Microsoft no longer supports. The company broke with policy and released a patch for those older systems, but it has both the engineering talent and the money to do so.

That won’t happen with low-cost IoT devices.

Those devices are built on the cheap, and the companies that make them don’t have the dedicated teams of security engineers ready to craft and distribute security patches. The economics of the IoT doesn’t allow for it. Even worse, many of these devices aren’t patchable. Remember last fall when the Mirai botnet infected hundreds of thousands of Internet-enabled digital video recorders, webcams and other devices and launched a massive denial-of-service attack that resulted in a host of popular websites dropping off the Internet? Most of those devices couldn’t be fixed with new software once they were attacked. The way you update your DVR is to throw it away and buy a new one.

Solutions aren’t easy and they’re not pretty. The market is not going to fix this unaided. Security is a hard-to-evaluate feature against a possible future threat, and consumers have long rewarded companies that provide easy-to-compare features and a quick time-to-market at its expense. We need to assign liabilities to companies that write insecure software that harms people, and possibly even issue and enforce regulations that require companies to maintain software systems throughout their life cycle. We may need minimum security standards for critical IoT devices. And it would help if the NSA got more involved in securing our information infrastructure and less in keeping it vulnerable so the government can eavesdrop.

I know this all sounds politically impossible right now, but we simply cannot live in a future where everything — from the things we own to our nation’s infrastructure ­– can be held for ransom by criminals again and again.

This essay previously appeared in the Washington Post.

Posted on May 23, 2017 at 5:55 AMView Comments

Google Discloses Details of an Unpatched Microsoft Vulnerability

Google’s Project Zero is serious about releasing the details of security vulnerabilities 90 days after they alert the vendors, even if they’re unpatched. It just exposed a nasty vulnerability in Microsoft’s browsers.

This is the second unpatched Microsoft vulnerability it exposed last week.

I’m a big fan of responsible disclosure. The threat to publish vulnerabilities is what puts pressure on vendors to patch their systems. But I wonder what competitive pressure is on the Google team to find embarrassing vulnerabilities in competitors’ products.

Posted on March 9, 2017 at 6:28 AMView Comments

Security Economics of the Internet of Things

Brian Krebs is a popular reporter on the cybersecurity beat. He regularly exposes cybercriminals and their tactics, and consequently is regularly a target of their ire. Last month, he wrote about an online attack-for-hire service that resulted in the arrest of the two proprietors. In the aftermath, his site was taken down by a massive DDoS attack.

In many ways, this is nothing new. Distributed denial-of-service attacks are a family of attacks that cause websites and other Internet-connected systems to crash by overloading them with traffic. The “distributed” part means that other insecure computers on the Internet — sometimes in the millions­ — are recruited to a botnet to unwittingly participate in the attack. The tactics are decades old; DDoS attacks are perpetrated by lone hackers trying to be annoying, criminals trying to extort money, and governments testing their tactics. There are defenses, and there are companies that offer DDoS mitigation services for hire.

Basically, it’s a size vs. size game. If the attackers can cobble together a fire hose of data bigger than the defender’s capability to cope with, they win. If the defenders can increase their capability in the face of attack, they win.

What was new about the Krebs attack was both the massive scale and the particular devices the attackers recruited. Instead of using traditional computers for their botnet, they used CCTV cameras, digital video recorders, home routers, and other embedded computers attached to the Internet as part of the Internet of Things.

Much has been written about how the IoT is wildly insecure. In fact, the software used to attack Krebs was simple and amateurish. What this attack demonstrates is that the economics of the IoT mean that it will remain insecure unless government steps in to fix the problem. This is a market failure that can’t get fixed on its own.

Our computers and smartphones are as secure as they are because there are teams of security engineers working on the problem. Companies like Microsoft, Apple, and Google spend a lot of time testing their code before it’s released, and quickly patch vulnerabilities when they’re discovered. Those companies can support such teams because those companies make a huge amount of money, either directly or indirectly, from their software­ — and, in part, compete on its security. This isn’t true of embedded systems like digital video recorders or home routers. Those systems are sold at a much lower margin, and are often built by offshore third parties. The companies involved simply don’t have the expertise to make them secure.

Even worse, most of these devices don’t have any way to be patched. Even though the source code to the botnet that attacked Krebs has been made public, we can’t update the affected devices. Microsoft delivers security patches to your computer once a month. Apple does it just as regularly, but not on a fixed schedule. But the only way for you to update the firmware in your home router is to throw it away and buy a new one.

The security of our computers and phones also comes from the fact that we replace them regularly. We buy new laptops every few years. We get new phones even more frequently. This isn’t true for all of the embedded IoT systems. They last for years, even decades. We might buy a new DVR every five or ten years. We replace our refrigerator every 25 years. We replace our thermostat approximately never. Already the banking industry is dealing with the security problems of Windows 95 embedded in ATMs. This same problem is going to occur all over the Internet of Things.

The market can’t fix this because neither the buyer nor the seller cares. Think of all the CCTV cameras and DVRs used in the attack against Brian Krebs. The owners of those devices don’t care. Their devices were cheap to buy, they still work, and they don’t even know Brian. The sellers of those devices don’t care: they’re now selling newer and better models, and the original buyers only cared about price and features. There is no market solution because the insecurity is what economists call an externality: it’s an effect of the purchasing decision that affects other people. Think of it kind of like invisible pollution.

What this all means is that the IoT will remain insecure unless government steps in and fixes the problem. When we have market failures, government is the only solution. The government could impose security regulations on IoT manufacturers, forcing them to make their devices secure even though their customers don’t care. They could impose liabilities on manufacturers, allowing people like Brian Krebs to sue them. Any of these would raise the cost of insecurity and give companies incentives to spend money making their devices secure.

Of course, this would only be a domestic solution to an international problem. The Internet is global, and attackers can just as easily build a botnet out of IoT devices from Asia as from the United States. Long term, we need to build an Internet that is resilient against attacks like this. But that’s a long time coming. In the meantime, you can expect more attacks that leverage insecure IoT devices.

This essay previously appeared on Vice Motherboard.

Slashdot thread.

Here are some of the things that are vulnerable.

EDITED TO ADD (10/17: DARPA is looking for IoT-security ideas from the private sector.

Posted on October 10, 2016 at 10:26 AMView Comments

Sidebar photo of Bruce Schneier by Joe MacInnis.