iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
Use server-side, account-aware throttling to slow repeated password guesses, but avoid making a victim’s account permanently unavailable after unauthenticated failures. Combine progressive delays with risk checks, challenges when warranted, and a safe recovery route. Set limits for your threat model: NIST’s 100-consecutive-failure figure is an upper bound for applicable authenticator requirements, not a universal recommended setting for every website.
Why can a login limit lock out the wrong person?
A hard lock triggered by failed attempts can turn a security control into a denial-of-service tool: an attacker who knows a username can repeatedly submit wrong passwords and prevent the real account holder from signing in. A source-IP-only limit creates a different weakness. Attackers can distribute attempts across addresses, so the limit may never meaningfully constrain guessing against one account.
OWASP’s Authentication Cheat Sheet frames lockout design around three choices: the number of failures, the observation window, and the duration of the restriction. Those choices should balance resistance to guessing against the ease with which a third party can disrupt an account. The guidance does not establish one threshold that fits every application.
Free tools Windows power users keep installed
One-click scans. No signup required.
What should the limit count?
Enforce throttling on the server and associate failed-attempt state with the account, not only with the source IP. This makes address rotation less effective. IP address and other request context can supplement the account counter, but should not replace it.
#1 Best Overall
- POWERFUL SECURITY KEY: The Security Key C NFC is the essential physical passkey for protecting your digital life from phishing attacks. It ensures only you can access your accounts.
- WORKS WITH 1000+ ACCOUNTS: Compatible with Google, Microsoft, and Apple. A single Security Key C NFC secures 100 of your favorite accounts, including email, password managers, and more.
- FAST & CONVENIENT LOGIN: Plug in your Security Key C NFC via USB-C and tap it, or tap it against your phone (NFC) to authenticate. No batteries, no internet connection, and no extra fees required.
- TRUSTED PASSKEY TECHNOLOGY: Uses the latest passkey standards (FIDO2/WebAuthn & FIDO U2F) but does not support One-Time Passwords. For complex needs, check out the YubiKey 5 Series.
- BUILT TO LAST: Made from tough, waterproof, and crush-resistant materials. Manufactured in Sweden and programmed in the USA with the highest security standards.
Keep enough context to apply the policy consistently across the authentication routes that protect the same account. Decide what a successful authentication does to retry state: NIST SP 800-63B Revision 4 says successful authentication should reset the retry counts for the authenticators used in that successful authentication. Avoid a design in which a success on one route silently leaves a conflicting retry state on another.
Which throttling approach balances protection and access?
| Control | What it helps with | Main trade-off |
|---|---|---|
| Account-level threshold within an observation window | Constrains repeated guesses against one account, including attempts spread across IP addresses. | A hard lock based only on unauthenticated failures gives an attacker a way to target a victim. Choose threshold and window for the system’s threat model. |
| Progressively longer waits | Slows repeated guessing while leaving a path to try again. NIST recommends increasing waits as the account approaches its limit; OWASP describes exponential delay as an alternative to a fixed lockout duration. | Legitimate users also wait after mistakes. Make the delay understandable and test its effect on recovery and support. |
| Bot-detection or CAPTCHA challenge | Adds friction to automated attempts, especially when introduced after suspicious behavior or some failed attempts. | Challenges can be bypassed or outsourced, and may burden users. OWASP treats CAPTCHA as defense in depth, not a standalone control. |
| Risk-based checks | Can distinguish familiar patterns from unusual attempts using signals such as IP address, geolocation, request timing, or browser metadata. | Signals are imperfect. No single one establishes identity, and NIST does not prescribe a universal scoring recipe. |
How should you interpret NIST’s 100-attempt limit?
NIST SP 800-63B Revision 4, section 3.2.2, requires verifiers to implement rate limiting when required by the relevant authenticator type. Unless otherwise specified, it sets a maximum of 100 consecutive failed authentication attempts using a specific authenticator on one subscriber account before that authenticator is disabled. NIST describes 100 as an upper bound and permits lower limits. It is not a default product setting or a general recommendation to allow 100 failed web-password attempts.
Rank #2
- POWERFUL SECURITY KEY: The YubiKey 5C NFC is the most versatile physical passkey, protecting your digital life from phishing attacks. It ensures only you can access your accounts
- WORKS WITH 1000+ ACCOUNTS: Compatible with popular accounts like Google, Microsoft, and Apple. A single YubiKey 5C NFC secures 100+ of your favorite accounts, including email, password managers, and more
- FAST & CONVENIENT LOGIN: Plug in your YubiKey 5C NFC via USB and tap it, or tap it against your phone (NFC), to authenticate. No batteries, no internet connection, and no extra fees required
- MOST SECURE PASSKEY: Supports FIDO2/WebAuthn, FIDO U2F, Yubico OTP, OATH-TOTP/HOTP, Smart card (PIV), and OpenPGP. That means it’s versatile, working almost anywhere you need it
- PRIMARY & SPARE KEYS: Just like having a spare house key, we recommend buying two YubiKeys - one for daily use and one as a spare. That way you’ll never get locked out of your accounts
The standard also identifies ways to reduce the chance that rate limiting locks out a legitimate claimant: a bot-detection challenge, increasing waits as the account approaches its maximum, and risk-based signals. NIST SP 800-53 Revision 5 control AC-7 takes a separate, organization-defined approach to invalid logons and responses; its discussion notes that automatic lockouts are usually temporary because of denial-of-service risk. Neither standard supplies a universal consumer-site threshold.
The Tool Desk
Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →How can users recover without opening a weaker route?
Keep an appropriate account-recovery route available during a login restriction, and tell the user what to expect, such as when another attempt is allowed or how to begin recovery. OWASP specifically identifies forgotten-password access during lockout as one mitigation for lockout denial of service.
Rank #3
- POWERFUL SECURITY KEY: The YubiKey 5 NFC is the most versatile physical passkey, protecting your digital life from phishing attacks. It ensures only you can access your accounts
- WORKS WITH 1000+ ACCOUNTS: Compatible with popular accounts like Google, Microsoft, and Apple. A single YubiKey 5 NFC secures 100+ of your favorite accounts, including email, password managers, and more
- FAST & CONVENIENT LOGIN: Plug in your YubiKey 5 NFC via USB and tap it, or tap it against your phone (NFC), to authenticate. No batteries, no internet connection, and no extra fees required
- MOST SECURE PASSKEY: Supports FIDO2/WebAuthn, FIDO U2F, Yubico OTP, OATH-TOTP/HOTP, Smart card (PIV), and OpenPGP. That means it’s versatile, working almost anywhere you need it
- PRIMARY & SPARE KEYS: Just like having a spare house key, we recommend buying two YubiKeys - one for daily use and one as a spare. That way you’ll never get locked out of your accounts
Recovery itself must not become the easier way to take over or disrupt an account. Apply suitable verification to the recovery flow, and test its behavior while login throttling is active. OWASP’s Web Security Testing Guide notes that unlock mechanisms can expose their own denial-of-service path; time-based, self-service, and administrator-mediated approaches have different assurance and operational implications.
What should users and operators see?
Use externally consistent messages across login, registration, recovery, and API pathways where revealing whether an account exists would enable enumeration. At the same time, explain a restriction in a way that helps a legitimate user proceed without disclosing sensitive signals or confirming account details to an unauthenticated requester.
Rank #4
- POWERFUL SECURITY KEY: The Security Key NFC is the essential physical passkey for protecting your digital life from phishing attacks. It ensures only you can access your accounts.
- WORKS WITH 1000+ ACCOUNTS: Compatible with Google, Microsoft, and Apple. A single Security Key NFC secures 100 of your favorite accounts, including email, password managers, and more.
- FAST & CONVENIENT LOGIN: Plug in your Security Key NFC via USB-A and tap it, or tap it against your phone (NFC) to authenticate. No batteries, no internet connection, and no extra fees required.
- TRUSTED PASSKEY TECHNOLOGY: Uses the latest passkey standards (FIDO2/WebAuthn & FIDO U2F) but does not support One-Time Passwords. For complex needs, check out the YubiKey 5 Series.
- BUILT TO LAST: Made from tough, waterproof, and crush-resistant materials. Manufactured in Sweden and programmed in the USA with the highest security standards.
Log failed attempts and alert administrators to patterns that suggest credential stuffing, brute force, or related attacks, as OWASP Top 10:2025 recommends. Useful operational records should support investigation of patterns across accounts and requests while avoiding unnecessary exposure of sensitive authentication data.
How do you verify the design?
Test the policy across the actual login and recovery surface, not just one browser form. OWASP’s testing guidance includes checking whether a correct login still works after repeated failures and examining whether the unlock mechanism creates another denial-of-service path.
Best Value
- Security Key : Protect your online accounts against unauthorized access by using FIDO2 and U2F authentication with T110. It's the world's most protective security key that works with windows, Mac OS, Linux as well as Chrome, Firefox, Edge and many other major browsers.
- Certified with the new FIDO2 standard, T110 provides the benefit of fast login and strong protection against phishing, account takeover as well as many other online attactks.
- Works with : Bank of America, Github, Google, Microsoft, DUO, Twitter, Facebook, Dropbox, Apple, ebay, BINANCE, mor and more.
- Fits USB-A port : Insert the T110 security key into the USB-A port of each service and log in conveniently with one touch
- For the driver download and user guide, please visit TrustKey Solutions Home support page.
- Send repeated failures against one known account, then repeat from changing IP addresses to check that address rotation does not bypass account-aware throttling.
- Try correct credentials during a delay and after it expires; verify the intended behavior and that successful authentication updates applicable retry state.
- Exercise account recovery while a login restriction is active, including whether recovery can be abused to disrupt or take over the account.
- Check registration, web login, and API authentication for consistent policy enforcement and externally consistent account-outcome messages.
- Confirm the decision is enforced server-side and that logs and alerts capture useful attack patterns without revealing account existence to unauthenticated users.
When should you use a managed authentication system?
If your team cannot reliably maintain throttling, recovery, logging, and session controls across every authentication path, evaluate a trusted premade authentication or identity system. OWASP Top 10:2025 recommends considering such systems. Assess whether the system supports the controls and recovery behavior your application needs; the recommendation does not establish that any particular provider or configuration will prevent lockouts.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
