Tag Archives: zero day

Microsoft Secure Boot Bug

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2023/05/microsoft-secure-boot-bug.html

Microsoft is currently patching a zero-day Secure-Boot bug.

The BlackLotus bootkit is the first-known real-world malware that can bypass Secure Boot protections, allowing for the execution of malicious code before your PC begins loading Windows and its many security protections. Secure Boot has been enabled by default for over a decade on most Windows PCs sold by companies like Dell, Lenovo, HP, Acer, and others. PCs running Windows 11 must have it enabled to meet the software’s system requirements.

Microsoft says that the vulnerability can be exploited by an attacker with either physical access to a system or administrator rights on a system. It can affect physical PCs and virtual machines with Secure Boot enabled.

That’s important. This is a nasty vulnerability, but it takes some work to exploit it.

The problem with the patch is that it breaks backwards compatibility: “…once the fixes have been enabled, your PC will no longer be able to boot from older bootable media that doesn’t include the fixes.”


Not wanting to suddenly render any users’ systems unbootable, Microsoft will be rolling the update out in phases over the next few months. The initial version of the patch requires substantial user intervention to enable—you first need to install May’s security updates, then use a five-step process to manually apply and verify a pair of “revocation files” that update your system’s hidden EFI boot partition and your registry. These will make it so that older, vulnerable versions of the bootloader will no longer be trusted by PCs.

A second update will follow in July that won’t enable the patch by default but will make it easier to enable. A third update in “first quarter 2024” will enable the fix by default and render older boot media unbootable on all patched Windows PCs. Microsoft says it is “looking for opportunities to accelerate this schedule,” though it’s unclear what that would entail.

So it’ll be almost a year before this is completely fixed.

Hacks at Pwn2Own Vancouver 2023

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2023/03/hacks-at-pwn2own-vancouver-2023.html

An impressive array of hacks were demonstrated at the first day of the Pwn2Own conference in Vancouver:

On the first day of Pwn2Own Vancouver 2023, security researchers successfully demoed Tesla Model 3, Windows 11, and macOS zero-day exploits and exploit chains to win $375,000 and a Tesla Model 3.

The first to fall was Adobe Reader in the enterprise applications category after Haboob SA’s Abdul Aziz Hariri (@abdhariri) used an exploit chain targeting a 6-bug logic chain abusing multiple failed patches which escaped the sandbox and bypassed a banned API list on macOS to earn $50,000.

The STAR Labs team (@starlabs_sg) demoed a zero-day exploit chain targeting Microsoft’s SharePoint team collaboration platform that brought them a $100,000 reward and successfully hacked Ubuntu Desktop with a previously known exploit for $15,000.

Synacktiv (@Synacktiv) took home $100,000 and a Tesla Model 3 after successfully executing a TOCTOU (time-of-check to time-of-use) attack against the Tesla-Gateway in the Automotive category. They also used a TOCTOU zero-day vulnerability to escalate privileges on Apple macOS and earned $40,000.

Oracle VirtualBox was hacked using an OOB Read and a stacked-based buffer overflow exploit chain (worth $40,000) by Qrious Security’s Bien Pham (@bienpnn).

Last but not least, Marcin Wiązowski elevated privileges on Windows 11 using an improper input validation zero-day that came with a $30,000 prize.

The con’s second and third days were equally impressive.

Apple Patches iPhone Zero-Day

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/12/apple-patches-iphone-zero-day.html

The most recent iPhone update—to version 16.1.2—patches a zero-day vulnerability that “may have been actively exploited against versions of iOS released before iOS 15.1.”


Apple said security researchers at Google’s Threat Analysis Group, which investigates nation state-backed spyware, hacking and cyberattacks, discovered and reported the WebKit bug.

WebKit bugs are often exploited when a person visits a malicious domain in their browser (or via the in-app browser). It’s not uncommon for bad actors to find vulnerabilities that target WebKit as a way to break into the device’s operating system and the user’s private data. WebKit bugs can be “chained” to other vulnerabilities to break through multiple layers of a device’s defenses.

Microsoft Zero-Days Sold and then Used

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/07/microsoft-zero-days-sold-and-then-used.html

Yet another article about cyber-weapons arms manufacturers and their particular supply chain. This one is about Windows and Adobe Reader zero-day exploits sold by an Austrian company named DSIRF.

There’s an entire industry devoted to undermining all of our security. It needs to be stopped.

Zero-Day Vulnerabilities Are on the Rise

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/04/zero-day-vulnerabilities-are-on-the-rise.html

Both Google and Mandiant are reporting a significant increase in the number of zero-day vulnerabilities reported in 2021.


2021 included the detection and disclosure of 58 in-the-wild 0-days, the most ever recorded since Project Zero began tracking in mid-2014. That’s more than double the previous maximum of 28 detected in 2015 and especially stark when you consider that there were only 25 detected in 2020. We’ve tracked publicly known in-the-wild 0-day exploits in this spreadsheet since mid-2014.

While we often talk about the number of 0-day exploits used in-the-wild, what we’re actually discussing is the number of 0-day exploits detected and disclosed as in-the-wild. And that leads into our first conclusion: we believe the large uptick in in-the-wild 0-days in 2021 is due to increased detection and disclosure of these 0-days, rather than simply increased usage of 0-day exploits.


In 2021, Mandiant Threat Intelligence identified 80 zero-days exploited in the wild, which is more than double the previous record volume in 2019. State-sponsored groups continue to be the primary actors exploiting zero-day vulnerabilities, led by Chinese groups. The proportion of financially motivated actors­ — particularly ransomware groups — ­deploying zero-day exploits also grew significantly, and nearly 1 in 3 identified actors exploiting zero-days in 2021 was financially motivated. Threat actors exploited zero-days in Microsoft, Apple, and Google products most frequently, likely reflecting the popularity of these vendors. The vast increase in zero-day exploitation in 2021, as well as the diversification of actors using them, expands the risk portfolio for organizations in nearly every industry sector and geography, particularly those that rely on these popular systems.

News article.

Chrome Zero-Day from North Korea

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/03/chrome-zero-day-from-north-korea.html

North Korean hackers have been exploiting a zero-day in Chrome.

The flaw, tracked as CVE-2022-0609, was exploited by two separate North Korean hacking groups. Both groups deployed the same exploit kit on websites that either belonged to legitimate organizations and were hacked or were set up for the express purpose of serving attack code on unsuspecting visitors. One group was dubbed Operation Dream Job, and it targeted more than 250 people working for 10 different companies. The other group, known as AppleJeus, targeted 85 users.


The attackers made use of an exploit kit that contained multiple stages and components in order to exploit targeted users. The attackers placed links to the exploit kit within hidden iframes, which they embedded on both websites they owned as well as some websites they compromised.

The kit initially serves some heavily obfuscated javascript used to fingerprint the target system. This script collected all available client information such as the user-agent, resolution, etc. and then sent it back to the exploitation server. If a set of unknown requirements were met, the client would be served a Chrome RCE exploit and some additional javascript. If the RCE was successful, the javascript would request the next stage referenced within the script as “SBX”, a common acronym for Sandbox Escape. We unfortunately were unable to recover any of the stages that followed the initial RCE.

Careful to protect their exploits, the attackers deployed multiple safeguards to make it difficult for security teams to recover any of the stages. These safeguards included:

  • Only serving the iframe at specific times, presumably when they knew an intended target would be visiting the site.
  • On some email campaigns the targets received links with unique IDs. This was potentially used to enforce a one-time-click policy for each link and allow the exploit kit to only be served once.
  • The exploit kit would AES encrypt each stage, including the clients’ responses with a session-specific key.
  • Additional stages were not served if the previous stage failed.

Although we recovered a Chrome RCE, we also found evidence where the attackers specifically checked for visitors using Safari on MacOS or Firefox (on any OS), and directed them to specific links on known exploitation servers. We did not recover any responses from those URLs.

If you’re a Chrome user, patch your system now.

CVE-2022-26143: A Zero-Day vulnerability for launching UDP amplification DDoS attacks

Post Syndicated from Omer Yoachimik original https://blog.cloudflare.com/cve-2022-26143-amplification-attack/

CVE-2022-26143: A Zero-Day vulnerability for launching UDP amplification DDoS attacks

CVE-2022-26143: A Zero-Day vulnerability for launching UDP amplification DDoS attacks

A zero-day vulnerability in the Mitel MiCollab business phone system has recently been discovered (CVE-2022-26143). This vulnerability, called TP240PhoneHome, which Cloudflare customers are already protected against, can be used to launch UDP amplification attacks. This type of attack reflects traffic off vulnerable servers to victims, amplifying the amount of traffic sent in the process by an amplification factor of 220 billion percent in this specific case.

Cloudflare has been actively involved in investigating the TP240PhoneHome exploit, along with other members of the InfoSec community. Read our joint disclosure here for more details. As far as we can tell, the vulnerability has been exploited as early as February 18, 2022. We have deployed emergency mitigation rules to protect Cloudflare customers against the amplification DDoS attacks.

Mitel has been informed of the vulnerability. As of February 22, they have issued a high severity security advisory advising their customers to block exploitation attempts using a firewall, until a software patch is made available. Cloudflare Magic Transit customers can use the Magic Firewall to block external traffic to the exposed Mitel UDP port 10074 by following the example in the screenshot below, or by pasting the following expression into their Magic Firewall rule editor and selecting the Block action:

(udp.dstport eq 10074).

CVE-2022-26143: A Zero-Day vulnerability for launching UDP amplification DDoS attacks
Creating a Magic Firewall rule to block traffic to port 10074

To learn more, register for our webinar on March 23rd, 2022.

Exploiting the vulnerability to launch DDoS attacks

Mitel Networks is based in Canada and provides business communications and collaboration products to over 70 million business users around the world. Amongst their enterprise collaboration products is the aforementioned Mitel MiCollab platform, known to be used in critical infrastructure such as municipal governments, schools, and emergency services. The vulnerability was discovered in the Mitel MiCollab platform.

The vulnerability manifests as an unauthenticated UDP port that is incorrectly exposed to the public Internet. The call control protocol running on this port can be used to, amongst other things, issue the debugging command startblast. This command does not place real telephone calls; rather, it simulates a “blast” of calls in order to test the system. For each test call that is made, two UDP packets are emitted in response to the issuer of the command.

According to the security advisory, the exploit can “allow a malicious actor to gain unauthorized access to sensitive information and services, cause performance degradations or a denial of service condition on the affected system. If exploited with a denial of service attack, the impacted system may cause significant outbound traffic impacting availability of other services.

Since this is an unauthenticated and connectionless UDP-based protocol, you can use spoofing to direct the response traffic toward any IP and port number — and by doing so, reflect and amplify a DDoS attack to the victim.

We’ve mainly focused on the amplification vector because it can be used to hurt the whole Internet, but the phone systems themselves can likely be hurt in other ways with this vulnerability. This UDP call control port offers many other commands. With some work, it’s likely that you could use this UDP port to commit toll fraud, or to simply render the phone system inoperable. We haven’t assessed these other possibilities, because we do not have access to a device that we can safely test with.

The good news

Fortunately, only a few thousand of these devices are improperly exposed to the public Internet, meaning that this vector can “only” achieve several hundred million packets per second total. This volume of traffic can cause major outages if you’re not protected by an always-on automated DDoS protection service, but it’s nothing to be concerned with if you are.

Furthermore, an attacker can’t run multiple commands at the same time. Instead, the server queues up commands and executes them serially. The fact that you can only launch one attack at a time from these devices, mixed with the fact that you can make that attack for many hours, has fascinating implications. If an attacker chooses to start an attack by specifying a very large number of packets, then that box is “burned” – it can’t be used to attack anyone else until the attack completes.

How Cloudflare detects and mitigates DDoS attacks

To defend organizations against DDoS attacks, we built and operate software-defined systems that run autonomously. They automatically detect and mitigate DDoS attacks across our entire network.

Initially, traffic is routed through the Internet via BGP Anycast to the nearest Cloudflare edge data center. Once the traffic reaches our data center, our DDoS systems sample it asynchronously allowing for out-of-path analysis of traffic without introducing latency penalties.

The analysis is done using data streaming algorithms. Packet samples are compared to the fingerprints and multiple real-time signatures are created based on the dynamic masking of various fingerprint attributes. Each time another packet matches one of the signatures, a counter is increased. When the system qualifies an attack, i.e., the activation threshold is reached for a given signature, a mitigation rule is compiled and pushed inline. The mitigation rule includes the real-time signature and the mitigation action, e.g., drop.

CVE-2022-26143: A Zero-Day vulnerability for launching UDP amplification DDoS attacks

You can read more about our autonomous DDoS protection systems and how they work in our joint-disclosure technical blog post.

Helping build a better Internet

Cloudflare’s mission is to help build a better Internet. A better Internet is one that is more secure, faster, and reliable for everyone — even in the face of DDoS attacks and emerging zero-day threats. As part of our mission, since 2017, we’ve been providing unmetered and unlimited DDoS protection for free to all of our customers. Over the years, it has become increasingly easier for attackers to launch DDoS attacks. To counter the attacker’s advantage, we want to make sure that it is also easy and free for organizations of all sizes to protect themselves against DDoS attacks of all types.

Not using Cloudflare yet? Start now.

New DeadBolt Ransomware Targets NAT Devices

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2022/01/new-deadbolt-ransomware-targets-nat-devices.html

There’s a new ransomware that targets NAT devices made by QNAP:

The attacks started today, January 25th, with QNAP devices suddenly finding their files encrypted and file names appended with a .deadbolt file extension.

Instead of creating ransom notes in each folder on the device, the QNAP device’s login page is hijacked to display a screen stating, “WARNING: Your files have been locked by DeadBolt”….


BleepingComputer is aware of at least fifteen victims of the new DeadBolt ransomware attack, with no specific region being targeted.

As with all ransomware attacks against QNAP devices, the DeadBolt attacks only affect devices accessible to the Internet.

As the threat actors claim the attack is conducted through a zero-day vulnerability, it is strongly advised that all QNAP users disconnect their devices from the Internet and place them behind a firewall.

More Log4j News

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2021/12/more-log4j-news.html

Log4j is being exploited by all sorts of attackers, all over the Internet:

At that point it was reported that there were over 100 attempts to exploit the vulnerability every minute. “Since we started to implement our protection we prevented over 1,272,000 attempts to allocate the vulnerability, over 46% of those attempts were made by known malicious groups,” said cybersecurity company Check Point.

And according to Check Point, attackers have now attempted to exploit the flaw on over 40% of global networks.

And a second vulnerability was found, in the patch for the first vulnerability. This is likely not to be the last.

On the Log4j Vulnerability

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2021/12/on-the-log4j-vulnerability.html

It’s serious:

The range of impacts is so broad because of the nature of the vulnerability itself. Developers use logging frameworks to keep track of what happens in a given application. To exploit Log4Shell, an attacker only needs to get the system to log a strategically crafted string of code. From there they can load arbitrary code on the targeted server and install malware or launch other attacks. Notably, hackers can introduce the snippet in seemingly benign ways, like by sending the string in an email or setting it as an account username.

Threat advisory from Cisco. Cloudflare found it in the wild before it was disclosed. CISA is very concerned, saying that hundreds of millions of devices are likely affected.

MacOS Zero-Day Used against Hong Kong Activists

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2021/11/macos-zero-day-used-against-hong-kong-activists.html

Google researchers discovered a MacOS zero-day exploit being used against Hong Kong activists. It was a “watering hole” attack, which means the malware was hidden in a legitimate website. Users visiting that website would get infected.

From an article:

Google’s researchers were able to trigger the exploits and study them by visiting the websites compromised by the hackers. The sites served both iOS and MacOS exploit chains, but the researchers were only able to retrieve the MacOS one. The zero-day exploit was similar to another in-the-wild vulnerability analyzed by another Google researcher in the past, according to the report.

In addition, the zero-day exploit used in this hacking campaign is “identical” to an exploit previously found by cybersecurity research group Pangu Lab, Huntley said. Pangu Lab’s researchers presented the exploit at a security conference in China in April of this year, a few months before hackers used it against Hong Kong users.

The exploit was discovered in August. Apple patched the vulnerability in September. China is, of course, the obvious suspect, given the victims.

EDITED TO ADD (11/15): Another story.

US Blacklists NSO Group

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2021/11/us-blacklists-nso-group.html

The Israeli cyberweapons arms manufacturer — and human rights violator, and probably war criminal — NSO Group has been added to the US Department of Commerce’s trade blacklist. US companies and individuals cannot sell to them. Aside from the obvious difficulties this causes, it’ll make it harder for them to buy zero-day vulnerabilities on the open market.

This is another step in the ongoing US actions against the company.

The Proliferation of Zero-days

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2021/09/the-proliferation-of-zero-days.html

The MIT Technology Review is reporting that 2021 is a blockbuster year for zero-day exploits:

One contributing factor in the higher rate of reported zero-days is the rapid global proliferation of hacking tools.

Powerful groups are all pouring heaps of cash into zero-days to use for themselves — and they’re reaping the rewards.

At the top of the food chain are the government-sponsored hackers. China alone is suspected to be responsible for nine zero-days this year, says Jared Semrau, a director of vulnerability and exploitation at the American cybersecurity firm FireEye Mandiant. The US and its allies clearly possess some of the most sophisticated hacking capabilities, and there is rising talk of using those tools more aggressively.


Few who want zero-days have the capabilities of Beijing and Washington. Most countries seeking powerful exploits don’t have the talent or infrastructure to develop them domestically, and so they purchase them instead.


It’s easier than ever to buy zero-days from the growing exploit industry. What was once prohibitively expensive and high-end is now more widely accessible.


And cybercriminals, too, have used zero-day attacks to make money in recent years, finding flaws in software that allow them to run valuable ransomware schemes.

“Financially motivated actors are more sophisticated than ever,” Semrau says. “One-third of the zero-days we’ve tracked recently can be traced directly back to financially motivated actors. So they’re playing a significant role in this increase which I don’t think many people are giving credit for.”


No one we spoke to believes that the total number of zero-day attacks more than doubled in such a short period of time — just the number that have been caught. That suggests defenders are becoming better at catching hackers in the act.

You can look at the data, such as Google’s zero-day spreadsheet, which tracks nearly a decade of significant hacks that were caught in the wild.

One change the trend may reflect is that there’s more money available for defense, not least from larger bug bounties and rewards put forward by tech companies for the discovery of new zero-day vulnerabilities. But there are also better tools.

Interesting Privilege Escalation Vulnerability

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2021/08/interesting-privilege-escalation-vulnerability.html

If you plug a Razer peripheral (mouse or keyboard, I think) into a Windows 10 or 11 machine, you can use a vulnerability in the Razer Synapse software — which automatically downloads — to gain SYSTEM privileges.

It should be noted that this is a local privilege escalation (LPE) vulnerability, which means that you need to have a Razer devices and physical access to a computer. With that said, the bug is so easy to exploit as you just need to spend $20 on Amazon for Razer mouse and plug it into Windows 10 to become an admin.

Paragon: Yet Another Cyberweapons Arms Manufacturer

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2021/08/paragon-yet-another-cyberweapons-arms-manufacturer.html

Forbes has the story:

Paragon’s product will also likely get spyware critics and surveillance experts alike rubbernecking: It claims to give police the power to remotely break into encrypted instant messaging communications, whether that’s WhatsApp, Signal, Facebook Messenger or Gmail, the industry sources said. One other spyware industry executive said it also promises to get longer-lasting access to a device, even when it’s rebooted.


Two industry sources said they believed Paragon was trying to set itself apart further by promising to get access to the instant messaging applications on a device, rather than taking complete control of everything on a phone. One of the sources said they understood that Paragon’s spyware exploits the protocols of end-to-end encrypted apps, meaning it would hack into messages via vulnerabilities in the core ways in which the software operates.

Read that last sentence again: Paragon uses unpatched zero-day exploits in the software to hack messaging apps.

China Taking Control of Zero-Day Exploits

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2021/07/china-taking-control-of-zero-day-exploits.html

China is making sure that all newly discovered zero-day exploits are disclosed to the government.

Under the new rules, anyone in China who finds a vulnerability must tell the government, which will decide what repairs to make. No information can be given to “overseas organizations or individuals” other than the product’s manufacturer.

No one may “collect, sell or publish information on network product security vulnerabilities,” say the rules issued by the Cyberspace Administration of China and the police and industry ministries.

This just blocks the cyber-arms trade. It doesn’t prevent researchers from telling the products’ companies, even if they are outside of China.

Details of the REvil Ransomware Attack

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2021/07/details-of-the-revil-ransomware-attack.html

ArsTechnica has a good story on the REvil ransomware attack of last weekend, with technical details:

This weekend’s attack was carried out with almost surgical precision. According to Cybereason, the REvil affiliates first gained access to targeted environments and then used the zero-day in the Kaseya Agent Monitor to gain administrative control over the target’s network. After writing a base-64-encoded payload to a file named agent.crt the dropper executed it.


The ransomware dropper Agent.exe is signed with a Windows-trusted certificate that uses the registrant name “PB03 TRANSPORT LTD.” By digitally signing their malware, attackers are able to suppress many security warnings that would otherwise appear when it’s being installed. Cybereason said that the certificate appears to have been used exclusively by REvil malware that was deployed during this attack.

To add stealth, the attackers used a technique called DLL Side-Loading, which places a spoofed malicious DLL file in a Windows’ WinSxS directory so that the operating system loads the spoof instead of the legitimate file. In the case here, Agent.exe drops an outdated version that is vulnerable to DLL Side-Loading of “msmpeng.exe,” which is the file for the Windows Defender executable.

Once executed, the malware changes the firewall settings to allow local windows systems to be discovered. Then, it starts to encrypt the files on the system….

REvil is demanding $70 million for a universal decryptor that will recover the data from the 1,500 affected Kaseya customers.

More news.

Note that this is yet another supply-chain attack. Instead of infecting those 1,500 networks directly, REvil infected a single managed service provider. And it leveraged a zero-day vulnerability in that provider.

EDITED TO ADD (7/13): Employees warned Kaseya’s management for years about critical security flaws, but they were ignored.

On Vulnerability-Adjacent Vulnerabilities

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2021/02/on-vulnerability-adjacent-vulnerabilities.html

At the virtual Enigma Conference, Google’s Project Zero’s Maggie Stone gave a talk about zero-day exploits in the wild. In it, she talked about how often vendors fix vulnerabilities only to have the attackers tweak their exploits to work again. From a MIT Technology Review article:

Soon after they were spotted, the researchers saw one exploit being used in the wild. Microsoft issued a patch and fixed the flaw, sort of. In September 2019, another similar vulnerability was found being exploited by the same hacking group.

More discoveries in November 2019, January 2020, and April 2020 added up to at least five zero-day vulnerabilities being exploited from the same bug class in short order. Microsoft issued multiple security updates: some failed to actually fix the vulnerability being targeted, while others required only slight changes that required just a line or two to change in the hacker’s code to make the exploit work again.


“What we saw cuts across the industry: Incomplete patches are making it easier for attackers to exploit users with zero-days,” Stone said on Tuesday at the security conference Enigma. “We’re not requiring attackers to come up with all new bug classes, develop brand new exploitation, look at code that has never been researched before. We’re allowing the reuse of lots of different vulnerabilities that we previously knew about.”


Why aren’t they being fixed? Most of the security teams working at software companies have limited time and resources, she suggests — and if their priorities and incentives are flawed, they only check that they’ve fixed the very specific vulnerability in front of them instead of addressing the bigger problems at the root of many vulnerabilities.

Another article on the talk.

This is an important insight. It’s not enough to patch existing vulnerabilities. We need to make it harder for attackers to find new vulnerabilities to exploit. Closing entire families of vulnerabilities, rather than individual vulnerabilities one at a time, is a good way to do that.