Signup Functionality Hunting

Objective

Find flaws in registration that lead to account takeover, enumeration, or privilege escalation.

Attribution: Methodology from KathanP19/HowToHunt — Sign_Up_Functionality. Licensed GPL-3.0.

Testing Methodology

# Duplicate account
curl -X POST https://target.com/register -d "email=victim@target.com&password=pass123"
curl -X POST https://target.com/register -d "email=victim@target.com&password=pass456" # 200 = duplicate allowed

# Email verification bypass
# Register, intercept verification request, change email param
POST /verify?email=attacker@evil.com&code=1234
# Change to victim@target.com with same code

# Weak validation
curl -X POST https://target.com/register -d "email=test@test&password=1" # short/invalid accepted?

# Check for auto-login after signup without verification

References

• HowToHunt — Signup