How to prevent malicious password reset abuse and hard bounces?

Summary

Preventing malicious password reset abuse and hard bounces necessitates a multi-layered approach. Implementing rate limiting, CAPTCHA, strong and unique reset tokens, account lockout policies, and bot detection mechanisms are crucial. Monitoring user agent logs for outdated browsers, enforcing strong password complexity requirements, and leveraging multi-factor authentication further enhance security. Addressing password reset process vulnerabilities like account enumeration and weak tokens is vital. Monitoring feedback loops and using double opt-in email verification helps remove abusive users.

Key findings

  • Rate Limiting: Limiting password reset requests prevents flooding the system and brute-force attacks.
  • CAPTCHA: CAPTCHA ensures requests are from humans, preventing bot-driven abuse.
  • Secure Tokens: Using strong, unique, expiring reset tokens prevents replay attacks and unauthorized access.
  • Account Lockout: Account lockout policies deter attackers by temporarily disabling accounts after failed attempts.
  • Bot Detection: Bot detection and mitigation block malicious bots flooding the password reset endpoint.
  • User Agent Monitoring: Monitoring user agent logs identifies attacks from outdated browsers.
  • Password Complexity: Strong password complexity requirements reduce successful password guessing.
  • Multi-Factor Authentication (MFA): MFA adds an extra layer of security before allowing password changes.
  • Vulnerability Mitigation: Addressing vulnerabilities like account enumeration and weak tokens prevents exploitation.
  • Email Verification: Using double opt-in email verification confirms email ownership and reduces abuse.
  • Feedback Loop Monitoring: Monitoring feedback loops identifies and removes abusive users from mailing lists.

Key considerations

  • IP Blocking: Block malicious IPs at the server level.
  • Security Team Involvement: Engage the security team for a comprehensive security strategy.
  • Consumer Mailbox Providers: Pay close attention to requests from consumer mailbox providers as potential malicious activity.
  • Bot Management Solutions: Utilize bot management solutions to identify and mitigate malicious bot traffic.
  • Block Old TLS Versions: Block older TLS versions to improve security.
  • Consider Email Verification: Consider using email verification with double opt-in to confirm user email addresses.
  • Set limits on attempts for an address/IP: Setting limits to password reset attempts from a single address or IP
  • Implement Account Lockout Policies: Implement account lockout policies after a certain number of failed password reset attempts

What email marketers say
11Marketer opinions

Preventing malicious password reset abuse and hard bounces involves a multi-layered approach. Key strategies include implementing rate limiting, CAPTCHA, account lockout policies, and bot detection mechanisms. Monitoring user agent logs, enforcing strong password complexity requirements, and leveraging multi-factor authentication further enhance security. Addressing vulnerabilities in the password reset process, such as account enumeration and weak tokens, is also crucial.

Key opinions

  • Rate Limiting: Limiting the number of password reset requests from the same IP address within a specific timeframe can prevent abuse.
  • CAPTCHA: Implementing CAPTCHA on the password reset page helps ensure a human is requesting the reset, mitigating bot-driven attacks.
  • Account Lockout: Account lockout policies after failed attempts deter attackers by temporarily disabling the account.
  • Bot Detection: Bot detection and mitigation strategies are essential for identifying and blocking malicious bots from flooding the password reset endpoint.
  • User Agent Monitoring: Checking the user agent in logs can help identify malicious attacks originating from outdated browser versions.
  • Password Complexity: Enforcing strong password complexity requirements reduces the likelihood of successful password guessing or brute-force attacks.
  • MFA: Multi-factor authentication adds an extra layer of security by requiring a second form of verification before allowing password changes.
  • Address Vulnerabilities: Failing to adequately protect the password reset process leaves applications vulnerable to enumeration, weak tokens, and lack of rate limiting which can all be exploited.

Key considerations

  • IP Blocking: If the malicious activity originates from a constant IP address, consider blocking the IP at the server level.
  • Password Complexity Enforcement: Implement and enforce strong password complexity requirements, including a mix of uppercase and lowercase letters, numbers, and symbols.
  • Bot Management Solutions: Implement a bot management solution to identify and mitigate malicious bots attempting password reset attacks.
  • Consider Email Verification: Consider using email verification with double opt-in is critical to prevent abuse and hard bounces, because it confirms that the user actually owns the email address.
  • Monitor Feedback Loops: Consider monitoring feedback loops (FBLs) with ISPs to identify and remove abusive users from your mailing lists which prevents future abuse and hard bounces.
Marketer view

Email marketer from Cloudflare shares that a bot management solution helps identify and mitigate malicious bots attempting password reset attacks. These solutions analyze traffic patterns, challenge suspicious requests, and block bots, preventing them from overwhelming the system with password reset requests.

June 2023 - Cloudflare
Marketer view

Email marketer from StackExchange explains that limiting password reset requests is a good idea. They suggest the best approach is to use a CAPTCHA after a few failed attempts to ensure a human is requesting the reset.

October 2022 - StackExchange
Marketer view

Email marketer from Reddit shares that implementing CAPTCHA on the password reset page, limiting the number of requests from the same IP address, and monitoring for unusual activity are effective ways to prevent abuse. They also suggest adding a delay between reset attempts.

May 2021 - Reddit
Marketer view

Email marketer from Security Forums shares that implementing account lockout policies after a certain number of failed password reset attempts can deter attackers. This involves temporarily disabling the account, preventing further attempts until the user verifies their identity or contacts support. The lockout duration should be carefully chosen to balance security and usability.

October 2021 - Security Forums
Marketer view

Email marketer from Imperva explains that bot detection and mitigation is critical for preventing password reset abuse. Identifying and blocking bots that attempt to flood the password reset endpoint can significantly reduce the risk of account takeovers. They recommend using behavioral analysis and device fingerprinting to distinguish between legitimate users and bots.

December 2021 - Imperva
Marketer view

Email marketer from troyhunt.com explains that failing to adequately protect the password reset process leaves applications vulnerable. Account enumeration, weak tokens, and lack of rate limiting are all cited as common issues that can be exploited.

July 2023 - troyhunt.com
Marketer view

Email marketer from Auth0 shares to make it extra safe, use Multi-Factor Authentication (MFA) in the password reset flow. After someone asks to reset their password but before they can actually change it, require them to prove it's really them with a second form of verification, like a code sent to their phone or email. This way, even if someone gets hold of the password reset link, they still can't change the password without that second verification step.

August 2024 - Auth0
Marketer view

Marketer from Email Geeks suggests checking the user agent in logs for malicious attacks from old browser versions and to block older TLS versions.

November 2024 - Email Geeks
Marketer view

Marketer from Email Geeks shares that if the IP address is constant, deny it at the server level or add logic to ignore the email addresses if present in the form. They suggest captcha as well.

May 2021 - Email Geeks
Marketer view

Email marketer from security.stackexchange.com shares that increasing the complexity requirements for passwords can decrease likelihood of abuse, they say 'use passwords with a combination of upper and lower case letters, numbers and punctuation symbols'.

December 2022 - security.stackexchange.com
Marketer view

Email marketer from Medium.com shares that they limit the amount of email reset password request from the same IP in specific amount of time period. Example: Not more than 5 request in 10 minutes.

September 2023 - Medium.com

What the experts say
5Expert opinions

Preventing malicious password reset abuse and associated hard bounces requires a multifaceted strategy. Experts recommend verifying email ownership through double opt-in, limiting password reset attempts, and blocking suspicious IPs. Monitoring feedback loops with ISPs helps to identify and remove abusive users. Additionally, understanding the source of email addresses used in password reset attempts and involving security teams are crucial steps.

Key opinions

  • Email Verification: Using double opt-in email verification confirms email ownership, reducing abuse and hard bounces.
  • Rate Limiting: Limiting the number of password reset attempts prevents abuse and potential brute-force attacks.
  • IP Blocking: Blocking suspicious IPs and TOR exit nodes can mitigate malicious activity.
  • Feedback Loop Monitoring: Regularly monitoring feedback loops with ISPs helps identify and remove abusive users, preventing future bounces.
  • Address Vulnerabilities: The bounces are unlikely to affect the sender's reputation if the email addresses used in password reset attempts are not at consumer mailbox providers.

Key considerations

  • Engage Security Team: Loop in your security team to develop a comprehensive strategy for protecting users and infrastructure.
  • Monitor Consumer Mailbox Providers: Pay special attention to attempts coming from consumer mailbox providers, as these are more likely to indicate malicious activity.
  • Implement reCAPTCHA: Use reCAPTCHA to reduce potential abuse.
Expert view

Expert from Email Geeks handles bogus address submissions by limiting attempts for an address/IP, blocking probing IPs/TOR exit nodes, and using reCAPTCHA.

February 2023 - Email Geeks
Expert view

Expert from Spam Resource explains to use email verification with double opt-in is critical to prevent abuse and hard bounces, because it confirms that the user actually owns the email address.

May 2022 - Spam Resource
Expert view

Expert from Email Geeks explains that if the email addresses used in the password reset attempts are not at consumer mailbox providers (like Gmail, Hotmail, AOL, Yahoo), the bounces are unlikely to affect the sender's reputation. They suggest the attempts might be to send spam or test for security problems.

February 2024 - Email Geeks
Expert view

Expert from Email Geeks recommends setting a limit on the number of password reset attempts before forcing the user to contact support and looping in the security team.

January 2023 - Email Geeks
Expert view

Expert from Word to the Wise, explains the importance of setting up and regularly monitoring feedback loops (FBLs) with ISPs to identify and remove abusive users from your mailing lists which prevents future abuse and hard bounces.

November 2024 - Word to the Wise

What the documentation says
3Technical articles

To prevent malicious password reset abuse and hard bounces, implementing rate limiting is crucial to restrict the number of reset requests within a timeframe. A secure reset mechanism includes verifying user identity, generating strong tokens, and ensuring token expiration. To prevent replay attacks it is important to use unique tokens per request, securely stored and associated with user accounts, and invalidate tokens after use.

Key findings

  • Rate Limiting: Rate limiting prevents attackers from flooding the system with requests.
  • Secure Reset Mechanism: A secure password reset mechanism involves identity verification, strong tokens, and token expiration.
  • Unique Tokens: Using a strong, unique token for each reset request and invalidating the token after use.

Key considerations

  • Mitigate Brute-Force Attacks: Rate limiting helps mitigate brute-force attacks and reduces account takeovers.
  • Prevent Account Enumeration: Prevent account enumeration to avoid abuse.
  • Prevent Replay Attacks: Implement checks to prevent replay attacks.
Technical article

Documentation from Google Cloud explains that implementing rate limiting on password reset requests is crucial. Rate limiting restricts the number of password reset requests a user can make within a specific timeframe, preventing attackers from flooding the system with requests. This helps mitigate brute-force attacks and reduces the likelihood of successful account takeovers.

October 2023 - Google Cloud
Technical article

Documentation from Auth0 explains that to secure the password reset flow, it's crucial to use a strong, unique token for each reset request. The token should be securely stored and associated with the user's account. Also, implement checks to prevent replay attacks by invalidating the token after use and ensuring it cannot be used multiple times.

September 2024 - Auth0
Technical article

Documentation from OWASP explains that a secure password reset mechanism should involve several key elements: verifying the user's identity through a secure channel (like email), generating a strong, unpredictable reset token, and ensuring the token expires after a short period. It also recommends preventing account enumeration and implementing rate limiting to avoid abuse.

March 2022 - OWASP