Microsoft: Most Windows 11 Users No Longer Need Third-Party Antivirus Software
Microsoft has stated that for most Windows 11 users, the built-in Windows Defender (presented as "Windows Security") provides sufficient protection if the system is kept updated, default security settings are enabled, and regular usage habits are followed, eliminating the need for third-party antivirus software.
During the Windows XP and Windows 7 eras, built-in protection from Microsoft was either non-existent or not highly valued, making products like Norton, McAfee, and Kaspersky standard components of user setups. However, starting with Windows 10, built-in security capabilities began to change significantly, and this transition was largely completed with Windows 11, allowing Microsoft to openly state that the system's built-in features are sufficient.
In its latest support documentation, Microsoft emphasizes that in typical home or personal use scenarios, as long as users install monthly security intelligence updates and "Patch Tuesday" updates on time, enable SmartScreen filtering, and download software from trusted sources, Windows Defender will continuously run in the background, scanning files, applications, and processes in real-time, without the need for additional third-party antivirus software for basic security. However, Microsoft also points out that Defender cannot completely replace third-party solutions in all cases, and there are still specific scenarios where additional security software is appropriate.
Microsoft does not completely dismiss third-party antivirus software. Reports indicate Microsoft believes that in large enterprise environments, organizations often require centralized management, advanced threat monitoring, and complex compliance strategies, which are strengths of some third-party enterprise-level security suites. In home scenarios, some users and parents value richer parental control features, identity protection services, or integrated VPNs – “bundled” value-added features – and therefore prefer to choose a security suite rather than just a basic antivirus engine.
At the same time, the article points out the real cost of installing third-party antivirus software: these programs often introduce additional background services, consume more memory and CPU resources, and may even conflict with the system's built-in protection, especially when multiple real-time monitoring programs coexist, which can easily lead to system abnormalities or performance fluctuations. Therefore, the industry generally recommends keeping only one “first-line” real-time protection engine, and for most Windows 11 users, this role is already defaulted to Windows Defender.
Despite Microsoft’s position, PC manufacturers often partner with security vendors like McAfee to pre-install trial versions of security suites to offset some hardware costs. These pre-installed programs, in the author’s view, are more like “bloatware.” The article’s author explicitly states that they have not installed additional antivirus programs since the Windows 10 era and habitually uninstall these pre-installed suites upon first contact with a new machine, because, according to Microsoft, “even without third-party antivirus, Windows 11 is already protecting your data.”
To understand why Microsoft is now confident enough to make this judgment, the article further analyzes the evolution and positioning of Defender. Microsoft emphasizes that Defender is no longer a simple file scanning tool, but a complete security protection stack deeply integrated into the operating system, presented to users through the “Windows Security” interface. Microsoft’s official materials show that Defender provides real-time scanning, behavior monitoring, and cloud protection, continuously checking files, applications, and processes during execution, and automatically obtaining the latest intelligence through Windows Update, avoiding the need for users to manually maintain virus databases.
In terms of detection methods, Defender no longer relies solely on traditional “signature” recognition. Considering that a large number of new threats do not match existing signatures, it combines behavioral analysis, heuristic algorithms, and cloud intelligence to attempt to capture unknown malware, zero-day attacks, and suspicious activity, thereby intercepting them before they can spread. This cloud-linked advantage is partly derived from Microsoft’s accumulated data in the enterprise security field: official data shows that Microsoft’s security systems process trillions of security signals and protect billions of endpoints every day, and this data feedback directly strengthens Defender’s threat intelligence capabilities and gradually integrates with Defender XDR, Sentinel, and other products.
Data from independent testing agencies provides third-party endorsement for Microsoft’s claims. According to AV-Test’s latest test results for home users on Windows 11, Microsoft Defender received a perfect score of 6/6 in all three categories: protection, usability, and performance. AV-Comparatives’ real-world protection tests also show that Defender’s interception rate has remained stable between 98.5% and 100%, with overall performance on par with many paid commercial antivirus software.
However, the report also points out that the security landscape itself has changed dramatically in recent years. AV-Test statistics show that more than 450,000 new malware samples are added every day, and IBM’s security report records a significant increase in ransomware attacks between 2023 and 2024. According to Verizon’s data breach investigation report, phishing emails remain the most common entry point for attackers, and human factors such as users clicking on links and downloading attachments make security protection increasingly complex.
In the face of this situation, simply relying on “antivirus software” is no longer enough to address all risks. Microsoft emphasizes in the text that Windows Security is now a hierarchical system, not a single application: from SmartScreen browsing and download protection, to Smart App Control blocking unknown applications, to controlled folder access and system permission management, the Defender engine is just one component. This mode of deep coupling with the kernel, update mechanism, and browser protection allows the system to respond before threats actually land, an advantage that general independent third-party tools cannot fully replicate.
At the functional level, the article breaks down several built-in protections that are more easily perceived by users in their daily lives. One is Microsoft Defender SmartScreen, which, when users visit websites, download files, or run applications, judges whether the object is trustworthy based on its reputation database, and pops up warnings for suspicious or insufficiently established content, intercepting a considerable proportion of attacks at the source. However, Microsoft reminds users to ensure that “reputation-based protection” is enabled, and SmartScreen’s prompts are more of a strong suggestion, not all scenarios will be forcibly blocked, and require user judgment.
The second is Smart App Control, which adopts a more aggressive strategy: for applications that are not signed or have insufficient reputation, the system can directly block their execution, rather than just warning users of the risk. This function mainly relies on code signing and Microsoft’s reputation system to determine whether an application is allowed to run, at the cost of potentially blocking some development tools or niche software, so it is disabled by default and is suitable for enabling for elderly people or children, or in a usage environment where “it’s better to install less software than to have problems.”
The third focuses on ransomware threats. Windows 11 defaults to enabling “Controlled Folder Access,” which implements modification permission control for key directories such as Documents, Desktop, and OneDrive, allowing only trusted programs to change their contents. If a stranger application attempts to operate on these files, the system will automatically intercept it and prompt the user to judge, and in many cases, this file-level interception is more effective than trying to recover the loss after “scanning.”
Regarding the antivirus needs of 2026, the article finally directs the discussion to a new variable: artificial intelligence. The author points out that in today’s world where AI tools are almost universally available, attackers can also use AI to generate more realistic phishing emails, obfuscate malicious code, and even hide malicious payloads in seemingly ordinary file formats. A recent attack disclosed by Microsoft shows that attackers used AI to generate code, disguising malicious payloads in SVG image files, posing challenges to traditional detection methods.
However, Microsoft also emphasizes that the advantages of AI also exist on the defensive side. Defender and its security stack will comprehensively analyze behavior patterns, infrastructure characteristics, information flows, and context, making it difficult for even AI-generated attacks to completely erase their traces. Microsoft even points out that AI-generated threats often leave unique patterns, which can themselves be used as new detection signals, providing more exploitable clues for automated defense.
Microsoft’s conclusion is: in the 2026 Windows 11 environment, for most users’ routine use scenarios, the system’s built-in security stack is sufficient to bear the first and main line of defense, covering real-time antivirus, behavior analysis, phishing protection, and system-level security control. Unless users have requirements such as enterprise-level centralized management, multi-platform unified security policies, or bundled services, they do not need to install third-party antivirus software for Windows PCs, and relying on Windows Security Center alone can maintain daily security.