The interface in this build was a refinement of the 2020 aesthetic. It used a "metro-style" tile layout.
Pros of the UI:
Cons:
The build used a multi-layered approach:
Why would anyone install the 2021 version today? Generally, one should not, because Kaspersky ends support for older versions after 2-3 years. However, for historical or offline use:
| Feature | 21.3.10.391 (2021) | Modern Kaspersky (2024+) | | :--- | :--- | :--- | | Ransomware rollback | Limited to 15 minutes | Unlimited via cloud backup | | VPN | 200 MB/day free | 300 MB/day free | | UI Speed | Slightly sluggish on low RAM | Optimized for SSDs | | Password Manager | Standalone app | Integrated into tray menu | | Support for Win 7 | Full support | Limited (extended support) |
Kaspersky Total Security 2021 (build 21.3.10.391) is a mature, full‑featured consumer security suite that combines layered malware protection with privacy, identity, parental‑control, backup/encryption and utility features. Strengths: strong detection history, broad feature set, useful extras (VPN, password vault, parental controls). Weaknesses: potential compatibility/driver issues on some Windows builds, UI complexity for nontechnical users, larger resource footprint than lightweight alternatives. Recommendation: good for families or users who want an all‑in‑one suite; less compelling if you prefer minimal system impact or only basic antivirus.
Version 21.3.10.391 shipped with a slightly dated but functional password manager. It generated strong passwords, auto-filled login forms, and synced via AES-256 encryption. The free tier allowed up to 15 passwords, while the Total Security subscription unlocked unlimited.
A two-way firewall replaced the Windows default firewall. For advanced users, version 21.3.10.391 allowed packet rules and application control, but for novices, the "Auto" mode worked flawlessly to block network intrusions. Kaspersky Total Security 2021 21.3.10.391 for W...
Q: Can I still activate Kaspersky Total Security 2021 in 2026? A: Possibly, if you have an unused activation code manufactured before 2022. However, Kaspersky's activation servers usually force-upgrade you to the latest version automatically during activation.
Q: Is 21.3.10.391 compatible with Windows 11? A: Not officially. It may install, but you risk system instability and "kernel security check failures."
Q: Does this version include a VPN? A: Yes, a limited free VPN (200MB/day) called Kaspersky Secure Connection was included.
Q: How does it compare to Windows Defender (in 2025)? A: The core engine of 21.3.10.391 is still superior in offline detection (without internet), whereas modern Windows Defender relies heavily on cloud lookups. However, Defender is safer due to regular Microsoft patches.
Disclaimer: This article is for informational and historical purposes. Always download security software from the official publisher (Kaspersky Lab). Using outdated software may violate your corporate security policy.
Kaspersky Total Security version 21.3.10.391 for Windows is an all-in-one protection suite designed to provide comprehensive defense against malware, ransomware, and online privacy threats. As of 2026, while this version remains functional on many systems, Kaspersky has transitioned its core consumer offerings to a new tiered structure (Standard, Plus, and Premium) with updated interfaces. Core Security Capabilities
This version includes the high-performing malware engine consistently recognized by independent labs.
Real-Time Antivirus: Continuously scans for viruses, Trojans, rootkits, and spyware. The interface in this build was a refinement
Automatic Exploit Prevention: Specifically for Windows, this feature identifies network exploits like EternalBlue that can crash operating systems.
Anti-Ransomware: Monitors for behavior typical of ransomware to block attacks before files are locked.
Two-Way Firewall: Manages both incoming and outgoing network requests to prevent unauthorized access. Privacy and Premium Features
The "Total Security" tier distinguishes itself from standard antivirus by including advanced privacy and family tools: Kaspersky Total Security 2022 updates
Here is the most likely full file name based on Kaspersky’s naming convention:
Kaspersky Total Security 2021 21.3.10.391 for Windows
Or, as it might appear in an installer file:
kts21.3.10.391en.exe
(where "en" could be replaced by another language code, e.g.,en-US,de,fr,ru) Cons: The build used a multi-layered approach: Why
If you need a full descriptive text for documentation or a download link, here’s an example:
"Kaspersky Total Security 2021 (version 21.3.10.391) for Windows – comprehensive multi-device security including antivirus, VPN, password manager, and parental controls."
Kaspersky Total Security 2021 (Version 21.3.10.391) Kaspersky Total Security 2021, specifically version 21.3.10.391
, is a legacy comprehensive security suite designed to protect Windows-based PCs from a wide array of digital threats. While Kaspersky has transitioned its main product line to new tiers (Standard, Plus, and Premium), this specific 2021 build remains a notable version for users on older operating systems or those with existing legacy licenses. Quick Facts Release Date:
The 21.3.10.391 version was widely deployed around March to June 2021. Operating System Support:
Compatible with Windows 7 (SP1+), 8, 8.1, 10, and Windows 11. Hardware Requirements:
Requires a 1 GHz processor, 1–2 GB of RAM, and approximately 1.5 GB of free disk space. Update Status: Legacy products like this version continue to receive virus database updates and standard technical support from Core Security Features Does KIS 21.3.10.391 Patch (C) rolling-out? [MERGED]
Kaspersky Total Security 2021 (Build 21.3.10.391) for Windows: An Informative Overview
Kaspersky Total Security 2021, specifically build 21.3.10.391, represents a significant iteration of Kaspersky Lab’s flagship security suite for Windows users. Released during a period of heightened digital dependency, this version aimed to provide a holistic defense mechanism against the evolving landscape of cyber threats.
Here is an informative breakdown of the key features, improvements, and context surrounding this specific release.