Account Fraud

TL;DR

• Account fraud = Fake or malicious accounts created on your platform
• Types: Bot signups, referral abuse, multi-accounting, fake reviews
• It's infrastructure for the fraud that comes next, not the loss itself
• Detect via: Device fingerprinting, email analysis, behavioral patterns
• Prevent with: CAPTCHA, email verification, phone verification, rate limiting

Someone signs up who isn't a customer. They're building for later.

Definition

Account fraud is fake or abusive accounts on your site or app. They don't cost you anything directly, and that's the trap: they enable promo abuse, refund fraud, fake reviews and organized attacks.

Why Fake Accounts Matter

They Enable	How
Promo abuse	New account = new discount
Referral fraud	Self-refer across accounts
Velocity evasion	Spread activity across accounts
Card testing	Disposable accounts for testing
Fake reviews	Boost or attack products
Resale fraud	Bulk buying limited items

Common Patterns

Bot Signups

Automated signups at scale. You'll see hundreds in an hour:

• Hundreds of accounts in hours
• Similar registration patterns
• Disposable email domains
• Generic or random usernames

Referral Fraud

Gaming referral programs:

• Self-referral across accounts
• "Referral farms" with fake accounts
• Quick signup → claim reward → abandon

Multi-Accounting

One person, multiple identities:

• Evade account-level limits
• Stack promotions
• Bypass bans or restrictions
• Separate fraud activity from "real" account

Fake Review Fraud

Social proof that isn't.

• Paid review rings
• Competitor sabotage
• Boosting new products artificially

Detection Signals

Registration Red Flags

Signal	Risk Level
Disposable email domain	High
Email pattern matches prior fraud	High
Device seen on multiple accounts	Critical
Registration velocity (time to complete)	Medium
Phone number from VoIP provider	Medium
Similar usernames/passwords	High

Email Analysis

Pattern	What It Suggests
john+1@gmail, john+2@gmail	Multi-accounting
Random string @domain.com	Bot-generated
Domain age < 30 days	Recently created for fraud
Known disposable domain	Temporary account
Email never used elsewhere	Fabricated for this account

Device Signals

Device fingerprinting reveals:

• Same device across multiple accounts
• Emulator or automation tools
• VPN/proxy usage
• Device recently associated with fraud

Behavioral Indicators

Behavior	Risk
No browsing before checkout	Scripted behavior
Immediate promo redemption	Promo farming
Referral link used instantly	Self-referral
Never returns after signup	Throwaway account
Review posted without purchase	Fake review ring

Prevention Strategies

At Registration

Control	What It Stops
CAPTCHA	Bot signups
Email verification	Disposable emails
Phone verification	Multi-accounting
Rate limiting	Mass registration
Device fingerprinting	Repeat registrations

Email Verification Best Practices

Level	Method	Stops
Basic	Send confirmation link	Fake emails
Medium	Check domain reputation	Disposable domains
Strong	Email risk scoring	Fraud-associated emails

Phone Verification

Check	Why
SMS verification	Ties to real phone
VoIP detection	Block virtual numbers
Phone line type	Mobile vs. landline vs. VoIP
Phone velocity	Same number, many accounts

Device Controls

Control	What It Catches
Device fingerprinting	Same device, different accounts
Emulator detection	Automated fraud tools
VPN detection	Hidden location
Device reputation	Known fraud devices

Account Linking

Here's what links accounts back together:

Attribute	What It Links
Device fingerprint	Same device = same person
IP address	Same network (less reliable)
Payment method	Same card across accounts
Shipping address	Same destination
Behavioral patterns	Similar navigation, timing

Response Playbook

Confirmed Fake Account

1. Block the account - Prevent further activity
2. Revoke benefits - Cancel promos, referral rewards
3. Blacklist identifiers - Device, email, phone
4. Check for linked accounts - Find the network
5. Update rules - Close the registration gap

Mass Signup Attack

1. Enable rate limiting - Slow the attack
2. Add friction - CAPTCHA, phone verification
3. Review recent signups - Find and remove fakes
4. Block infrastructure - IPs, devices, email patterns

Prevention Checklist

• CAPTCHA on registration
• Email verification required
• Disposable email domains blocked
• Device fingerprinting enabled
• Rate limiting on signup endpoints
• Phone verification for high-value actions
• VoIP/virtual number detection
• Account linking across devices
• Promo redemption limits per device

Next Steps

Preventing fake accounts?

1. Add device fingerprinting - Catch repeat registrations
2. Implement email verification - Block disposables
3. Set up rate limiting - Stop mass signups

Detecting fake accounts?

1. Check registration signals - Score risk at signup
2. Analyze email patterns - Catch multi-accounting
3. Link accounts - Find networks

Responding to fake accounts?

1. Follow response playbook - Block and revoke
2. Find linked accounts - Catch the full network
3. Update prevention - Close gaps

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Related Topics

• KYC & KYB for Fraud Prevention - When and how to verify identity at onboarding
• Identity Verification - Passive and documentary verification methods
• Promo Abuse - What fake accounts enable
• Fraud Rings - Organized multi-accounting
• Device Fingerprinting - Linking accounts by device
• Velocity Rules - Detecting signup patterns
• Card Testing - Often uses fake accounts
• Refund Fraud - Another fake account use case
• Account Takeover - When real accounts are hijacked
• Risk Scoring - Scoring at registration