Account Takeover (ATO) Checklist

This is a list of considerations when designing a sophisticated program to deal with account takeover threats.

View the associated threat model here.

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Infrastructure 🛠

Backend systems we rely on for detection and mitigation.

• General Rate Limiting
• User Event / Authentication Logs
• Device Identification (Cookie)
  • See reference like AuthTables
• Browser Fingerprinting (No Cookie)
  • See AmIUnique, Cover Your Tracks
  • 🚨 Do not mix with ads infra 🚨
• Device Verification (Email confirmation, SMS, Snail Mail)
• Customer Session, Password Reset Workflows (Backend)
• Link Shim
• Leaked Credential Pipeline (Backend)
  • Scraping (Pastebin, torrents, etc)
  • D a R k W e B and UnDErGroUnD
  • Periodically accessible dumps

ATO Indicators and Features 🕵️‍♀️

This section describes useful data that often needs to be acquired externally. These can be used in automated classification or to decorate investigation workflows with correlating info.

• Known proxies, tor, vps & colocation
• Observed malicious or compromised (Paid)
• Known Leaked Credentials
• Recent Sim Swap
• Domain intelligence
  • New domains
  • Disposable
  • Previously abused
• Address verification
• Cellular verification (VoIP detection)

Product / UX 🎮

All user facing experiences to help reduce risk within a product.

• MFA Options
  • Security keys, MFA, SMS, backup codes, etc.
• Knowledge Base and self-support
  • Reducing outreach to support for questions.
• Link Shim
  • Allows for disabling of external links when copy-pasted, emailed, or otherwise brought off platform.
  • Allows for warning messages before leaving platform.
• Victim and Witness escalation (Report Abuse)
  • Where victims of ATO report their issue.
  • Where witnesses of abuse report off-platform impact of on-platform ATO.
• Forced Password Reset Workflows
  • Retroactively ask users to change leaked passwords
    • Existing customers will have weak passwords.
  • Handle newly found customers from a leaked credential backend
    • Newly leaked credentials will cause a regular need to change customer passwords.
  • "Reset the password to your email"
    • Some investigations will indicate a customer's email is compromised, not their password.
  • Account re-enable
    • Self service workflows to get back online after you have intervened.
• Enforce password strength to prevent future weak passwords
  • New Registration
  • Password Change
  • Ongoing leaked / Newly weak
• Developer console prompts w/ a warning message
  • Example: Facebook
• Verification / Challenge workflows
  • When you are uncertain of the customer's location or device.
    • SMS
    • Email
    • Account / Identity Knowledge
    • ID Submission
    • CAPTCHA
• Stolen Session Detection
  • Example: Catching Compromised Cookies

Customer Service ☎️

Operational customer service interactions (Support tickets). Support organizations often escalate abuse at scale to engineering and have the most visibility into what is, or is not, working.

• Standard Org Language
  • What counts as ATO?
• Metrics / KPI
  • Tracking abuse going up or down.
• IR Escalation
  • Playbooks / Plans for creating an outage or getting engineering resources involved.
• Reset Workflows (Administrative Frontends)
  • Empowering scalable operations to mitigate abuse scenarios.

Investigations & Response 🚑

There will be periodic deep dives into ATO attacks to ask "what happened?". This section pertains to that perspective of work.

• Authentications are searchable by device, ip, user agent
  • Searches can pivot: Device to IP, IP to device, etc.
  • Bonus: Actions / Events are searchable
  • Bonus: All routes / Endpoints are searchable
• Tooling exists to reset bulk accounts that meet criteria
• Tooling exists to reverse transactions / changes that meet criteria.

Automation 🤖

Tying everything together for operational ATO systems. Engineering time is the least scalable, customer support hours are more scalable, fully automated systems are the most scalable.

• Customer service classifies abuse cases
• AI systems classifies authentication events
• Suspicious cases push customers to verify activity
• XFN meetings between groups to improve anti-abuse systematically

Anti-Phishing 🎣

Raising the bar against trivial credential stealing attacks which cause the most problems for unprepared organizations.

• SPF / DMARC / DKIM
• Brand protection (Internet scanning for your brand being spoofed)
• spoofed@ and customer phish reporting
• App store hunting
• Domain / ISP Takedowns
• Browser blacklisting
• Referer, hotlinks, adversary leaks