Microsoft Defender Archives

Tech Optimizer

September 25, 2026

We Tested 10 Best Antivirus Software for 2026

Cybersecurity threats are on the rise, with Verizon’s 2026 Data Breach Investigations Report indicating that 48% of breaches involve ransomware and 31% arise from software vulnerabilities. A review of leading antivirus programs assessed their effectiveness against various threats. Top antivirus software includes: - Bitdefender: Best overall, effective against various threats, perfect score from AV-TEST. - Norton 360: Best all-in-one suite, includes VPN and parental controls, perfect score from AV-TEST. - McAfee+ Premium: Best for families, unlimited device coverage, full marks from AV-TEST. - Malwarebytes: Best for simple protection, user-friendly interface, rated 5.5/6 by AV-TEST. - ESET NOD32: Best for advanced users, lightweight and fast, includes Gamer Mode. - Avast: Best free option, offers various scanning options, straightforward upgrade path. - Microsoft Defender: Built-in for Windows, essential protection, perfect score from AV-TEST. - Intego ONE: Best for Mac users, includes firewall and VPN. - Surfshark Antivirus: Combines antivirus and VPN services, real-time protection. - TotalAV: Best for beginners, combines antivirus with web security tools. The evaluation process included lab data from AV-TEST and AV-Comparatives, hands-on experience, and criteria such as malware protection, false positives, system performance impact, phishing protection, ease of use, platform coverage, additional security features, and pricing. Key metrics from antivirus lab tests include protection scores, false positives, and performance impact. The choice between antivirus software and internet security suites depends on individual needs. Antivirus software remains necessary, especially for Windows PCs, to complement other security measures.

Tech Optimizer

September 23, 2026

BigDiskBuster PoC Blocks Windows Defender Updates

A new tool named BigDiskBuster has been released on GitHub, which disrupts Microsoft Defender Antivirus by preventing it from installing updates. It does this by consuming available disk space during the update process, causing Defender to remain on its current version and unable to receive new platform or signature updates. BigDiskBuster operates as a local denial-of-service technique and requires prior access to the target machine to execute. The tool was created by researcher Abdelhamid Naceri, known as Nightmare Eclipse, who has previously worked on similar projects. As of now, there is no CVE identifier, patch, or advisory from Microsoft regarding this issue.

Winsage

September 23, 2026

New Windows Defender zero-day blocks Microsoft antivirus updates

Security researcher Abdelhamid Naceri, known as Nightmare Eclipse, released a zero-day exploit called BigDiskBuster that targets Microsoft Defender, preventing antivirus updates and leaving systems vulnerable. BigDiskBuster operates across all supported Windows versions and must run in the background to block updates. Naceri has previously released a similar exploit called UnDefend and has a history of releasing multiple zero-day exploits since April 2026 amid a dispute with Microsoft. Two weeks before BigDiskBuster, he introduced another exploit named ShieldCrash, which grants SYSTEM access and circumvents a patched flaw. Naceri's recent exploits include tools like LegacyHive, BlueHammer, RedSun, YellowKey, GreenPlasma, and MiniPlasma, all targeting Microsoft Defender and other Windows components. Microsoft has warned of potential legal action against malicious activities but has not commented on BigDiskBuster.

Winsage

September 22, 2026

Microsoft Defender is causing slow VLC startups. Here’s the fix

Recent investigations have shown that a specific update to Microsoft Defender has caused performance issues for VLC Media Player, particularly a slowdown in startup times. Jean-Baptiste Kempf, a VideoLAN developer, attributed this sluggishness to a bug in the Microsoft Defender update, which quarantined VLC's plug-in cache. The problematic Defender signature update is version 1.455.50.0, linked to Windows Update KB5121003 released on August 11th. Users can reset the plug-in cache to improve performance by either reinstalling VLC or using the built-in functionality to regenerate the cache with vlc-cache-gen.exe. Alternatively, users can reset preferences and cache files by searching for "VLC" and selecting the reset option. Microsoft has not yet provided a fix for these issues, and users may need to set an exclusion in Microsoft Defender for VLC Media Player to prevent unnecessary scans, enhancing its performance.

Tech Optimizer

September 21, 2026

Do You Really Need Antivirus in 2026?

The landscape of computer security has changed significantly over the past two decades. In 2026, antivirus protection remains important, but the need for separate third-party programs has decreased for many users due to the built-in Microsoft Defender in Windows 11, which is activated by default and effectively blocks 100% of common malware samples according to independent testing by AV-TEST. Windows 11 also includes additional protective features like SmartScreen and a robust Firewall. While dedicated security suites from companies like Norton and Bitdefender offer advanced functionalities, many users may find adequate protection with the built-in tools. Research from AV-Comparatives indicates that performance varies among security programs, particularly against real-world attacks. Phishing attacks accounted for approximately 60% of initial access points in incidents examined by the ENISA Threat Landscape report from 2025, highlighting that user behavior is a significant vulnerability. Modern web browsers and operating systems have enhanced their security measures, with Google Chrome, Microsoft Edge, macOS, and Android incorporating features to protect users from harmful websites and downloads. For the average Windows 11 user who keeps their system updated and practices safe browsing, built-in protection is generally sufficient, though paid antivirus options can provide additional tools.

Tech Optimizer

September 20, 2026

How to Remove a Keylogger: 12 Steps, 60 Min [2026]

A keylogger captures every keystroke made on a device and sends that information to an external source. In 2025, infostealer malware, including keyloggers, resulted in the theft of 642.4 million credentials from 13.2 million infections globally. In Australia, approximately 30,000 banking passwords were compromised between 2021 and 2025 due to this malware. The Australian Cyber Security Centre reported over 42,500 calls related to credential theft in one year, a 16% increase. Four main malware families dominate the landscape, with LummaC2 accounting for nearly 60% of credentials linked to infostealers in 2026. Keyloggers can be detected through signs such as typing lag, unexpected antivirus notifications, new browser extensions, and unexplained spikes in outbound data usage. Detection and removal steps include checking running processes, auditing startup programs, reviewing installed programs, running antivirus scans, and resetting passwords from a clean device. Keyloggers can infiltrate systems via phishing emails, malicious attachments, or compromised software downloads. Mobile devices can also be targeted by keyloggers disguised as legitimate apps.

Winsage

September 20, 2026

Microsoft Patches Windows Defender Bug That Kept Saying Your Antivirus Was Off

Microsoft resolved an issue in its Windows Security framework that incorrectly indicated Microsoft Defender Antivirus was disabled. This fix was implemented through Defender platform update 4.18.26080.4, released on September 17. The update installs automatically unless users have blocked mandatory security updates. Users had been receiving false alerts during system boot and intermittently afterward, which redirected them to the Windows Security home tab where settings appeared normal. Microsoft acknowledged the issue on August 28, affecting all supported versions of Windows and Windows Server with the latest Defender updates, but did not specify the triggering update. Users in the Windows Insider program reported similar warnings as early as June.

Tech Optimizer

September 19, 2026

Windows 11’s Defender kept falsely saying your antivirus was off, and Microsoft just fixed it

For nearly two months, Windows 11 users received persistent notifications from the Windows Security app falsely indicating that Microsoft Defender was disabled, despite it functioning properly. This issue, which began in early August, has been addressed with a security update from Microsoft. The false alerts affected all versions of Windows 11, Windows Server, and Windows 10, and were linked to a bug introduced with a recent Defender security update. Microsoft confirmed that no manual action is required from users to resolve the issue, as the fix will be automatically deployed to all PCs with mandatory security updates enabled. The problem was resolved in the Microsoft Defender Antivirus update (version 4.18.26080.4), released on September 17, 2026. Users can verify the status of Defender by checking Windows Security or using a PowerShell command.

Winsage

September 19, 2026

Microsoft fixes bug behind ‘Defender Antivirus is turned off’ alerts

Microsoft resolved an issue that caused misleading alerts indicating that Defender Antivirus was disabled after recent updates. This fix was confirmed in an update to the Windows release health dashboard and was implemented in the Microsoft Defender Antivirus update (version 4.18.26080.4) rolled out on September 17. The bug, acknowledged by Microsoft in late August, affected users in the Release Preview Channel of the Windows Insider program since at least June and impacted all supported versions of Windows clients and servers. Users received erroneous notifications in the Windows Security app prompting them to activate Microsoft Defender Antivirus, despite it functioning correctly. Misleading alerts could appear upon Windows startup and intermittently thereafter, even when notification settings were disabled.

Tech Optimizer

September 18, 2026

Best Free Antivirus for Windows 2026: 6 to Install, 1 to Skip

Avast Free Antivirus is recognized as the best free antivirus solution for Windows in 2026, achieving a perfect score from AV-TEST. It operates on the same engine as paid versions, providing comprehensive protection. Other notable free antivirus options include Bitdefender Antivirus Free, which is efficient for older systems; Microsoft Defender, a built-in option with solid protection; AVG AntiVirus Free, suited for older hardware; Avira Free Security, which includes additional tools; and Malwarebytes Free, best for cleaning infections. Each product generates revenue through upselling or data collection. Avast scored 99.78% in detection tests, while Bitdefender achieved 97.6%, and Microsoft Defender reached 99.93%. AVG matched Avast with a 99.97% protection rate, and Avira recorded 99.96%. Malwarebytes had a detection rate of 99.57%. Kaspersky is noted as a product to avoid due to misleading trial offers.