Skip to main content Tom's Guide Tom's Guide Search Tom's Guide View Profile Newsletters Best Picks Entertainment Apple WWDC 2025 Switch 2 Restock Best laptops Best Mattress Wordle Today Recommended reading Online Security 240 million Windows 10 users are vulnerable to six different hacker exploits — protect yourself now Online Security Microsoft just patched 134 Windows security flaws including a zero-day used by hackers — update your PC right now Online Security Windows PCs under threat from zero-day flaw used in ransomware attacks — update your computer right now Online Security 12 computer security mistakes you're probably making — and what to do instead Online Security This new Defendnot trojan can get Windows to disable its own antivirus software Online Security Security spring cleaning — 7 things you should do now to avoid getting hacked Online Security Macs under threat from thousands of hacked sites spreading malware — how to stay safe Online Security Malware & Adware Major Windows Secure Boot flaw can be used by hackers to install bootkit malware — update your PC right now Anthony Spadafora 10 June 2025 New flaw leaves most modern Windows PCs vulnerable to bootkit malware When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. (Image credit: Shutterstock) Sometimes the features designed to keep our computers safe can put us most at risk thanks to a worrying security flaw that can be exploited by hackers in their attacks. As reported by BleepingComputer, a new Secure Boot bypass (tracked as CVE-2025-3052) was recently discovered that can be used to disable Windows 11’s built-in security measures to install bootkit malware. Unlike your typical Windows malware, bootkit malware targets your computer’s boot process which allows an attacker to gain full control over your operating system before it even loads. To make matters worse, this type of malware is also persistent and can remain on your PC even after you reinstall Windows. You may like 240 million Windows 10 users are vulnerable to six different hacker exploits — protect yourself now Microsoft just patched 134 Windows security flaws including a zero-day used by hackers — update your PC right now Windows PCs under threat from zero-day flaw used in ransomware attacks — update your computer right now Here’s everything you need to know about this new Secure Boot flaw and why it’s imperative that you update your Windows PC right now to stay safe from any attacks exploiting it. Bypassing Secure Boot (Image credit: Shutterstock) According to a new blog post, this flaw was discovered by Binarly security researcher Alex Matrosov after he found a BIOS-flashing utility online. Signed with Microsoft’s UEFI signing certificate, the utility in question was originally designed for rugged tablets. However, it can run on any of the best Windows laptops or desktops with Secure Boot enabled. First introduced back in 2012 with the release of Windows 8, Secure Boot was created to protect against bootkit malware by ensuring that only trusted software could load during a PC’s startup sequence. Ironically, thanks to this flaw, Secure Boot-enabled PCs are now vulnerable to the very thing this security feature was designed to protect against. Following an investigation, it was discovered that the vulnerable module in the utility found by Mastrosov had been available online since at least the end of 2022, though it wasn’t until last year that it was uploaded to the malware detection service VirusTotal. Sign up to get the BEST of Tom's Guide direct to your inbox. Get instant access to breaking news, the hottest reviews, great deals and helpful tips. Contact me with news and offers from other Future brandsReceive email from us on behalf of our trusted partners or sponsorsBy submitting your information you agree to the Terms & Conditions and Privacy Policy and are aged 16 or over. To show how serious this flaw was, he and the team at Binarly created a proof of concept (PoC) exploit that set the LoadImage function used to enforce Secure Boot to zero which effectively disabled it. With this feature disabled, an attacker can install bootkit malware that can hide from both Windows and any security software installed on a system. Back in February of this year, Mastrosov disclosed the flaw to Microsoft and a fix for it was created. However, while it worked to address the flaw, the software giant determined that it impacted 13 other modules which then had to be fixed as well. How to keep your Windows PC safe (Image credit: Shutterstock) So how do you protect yourself from malware that starts before Windows even loads and can easily bypass the best antivirus software? Well, by updating your PC with the latest security updates from Microsoft. In June’s Patch Tuesday updates, Microsoft has included a fix for this major security flaw along with patches for other recently discovered vulnerabilities. However, the company has also added 14 new hashes to its Secure Boot dbx revocation list. Fortunately for you, this updated dbx file is contained within Microsoft’s latest round of Patch Tuesday updates. While installing the latest Windows updates may seem tedious at times, I highly recommend that you stop and take the time to do so as Microsoft often includes fixes for a variety of different security flaws while also adding new features to its operating system. Given that Patch Tuesday takes place on the second Tuesday of every month, at least you know ahead of time when these very important updates will arrive. This way, you can set aside the time needed to install them or better yet, set your PC to install them automatically. When dealing with security flaws that can bypass your antivirus software, the best identity theft protection services can help you recover your identity as well as any funds lost to malware or other scams as a result of them. Keep in mind though that for identity theft insurance to pay out, you need to be signed up for one of these services before an attack takes place. Although this Secure Boot bypass is worrying, it’s worth noting that it wasn’t exploited by hackers in the wild. Instead, security researchers created an exploit for it in order to show how dangerous this flaw could be if knowledge of it ended up in the wrong hands. Either way, it’s a great reminder as to why it’s so important to keep your PC (and all of the computers in your household for that matter) up to date. More from Tom's Guide Delete these 20 apps right now if you downloaded them from the Play Store — they’re malicious Macs under threat from new malware campaign impersonating major ISP These “great” deals on Facebook are not from Amazon, Rolex or Nordstrom – they’re from a network of scammers Today's Norton 360 with LifeLock deals 61% off - 1st year Norton 360 with LifeLock Select - Norton 360 with LifeLock Advantage - Norton 360 with LifeLock Ultimate Plus We check over 250 million products every day for the best prices See more Computing News Anthony Spadafora Social Links Navigation Managing Editor Security and Home Office Anthony Spadafora is the managing editor for security and home office furniture at Tom’s Guide where he covers everything from data breaches to password managers and the best way to cover your whole home or business with Wi-Fi. He also reviews standing desks, office chairs and other home office accessories with a penchant for building desk setups. Before joining the team, Anthony wrote for ITProPortal while living in Korea and later for TechRadar Pro after moving back to the US. Based in Houston, Texas, when he’s not writing Anthony can be found tinkering with PCs and game consoles, managing cables and upgrading his smart home. You must confirm your public display name before commenting Please logout and then login again, you will then be prompted to enter your display name. 240 million Windows 10 users are vulnerable to six different hacker exploits — protect yourself now Microsoft just patched 134 Windows security flaws including a zero-day used by hackers — update your PC right now Windows PCs under threat from zero-day flaw used in ransomware attacks — update your computer right now 12 computer security mistakes you're probably making — and what to do instead This new Defendnot trojan can get Windows to disable its own antivirus software Security spring cleaning — 7 things you should do now to avoid getting hacked Latest in Malware & Adware Macs under threat from new malware campaign impersonating major ISP — how to stay safe Dangerous new Android malware adds fake contacts to your phone while draining bank accounts — how to stay safe AirPlay flaw exposes all Apple devices to hacking over Wi-Fi — what you need to know This newly discovered iOS flaw could completely brick your iPhone with a single line of code Hackers are using Zoom to spread malware and take over PCs — here’s how to stay safe Hackers are impersonating banks to infect your Android phone with credit card-stealing malware Latest in News Marvel Animation debuts first episode of 'Eyes of Wakanda' — and it's got a surprising cameo I just tested a smart ring that can control your AR glasses — and this is what wearables have been missing Apple WWDC Interview: Craig Federighi and Joz on Siri delay, new Apple Intelligence features and what's next for AI Ben Affleck action thriller 'The Accountant 2' is Prime Video's newest No. 1 movie — and fans rate it 92% on Rotten Tomatoes Pedro Pascal and Joaquin Phoenix clash in A24's new 'Eddington' trailer — and it's already on my must-watch list IPVanish becomes the United Rugby Championship's official VPN partner LATEST ARTICLES Marvel Animation debuts first episode of 'Eyes of Wakanda' — and it's got a surprising cameo I just tested a smart ring that can control your AR glasses — and this is what wearables have been missing Mario Kart World kicks off the Nintendo Switch 2 era in colorful style — but there are some speed bumps along the way Score! 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