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Denwa
Other nuisance callsHigh risk

050-3801-3651 phone number information

Basic Information

Number Type
IP phone (050)

Number overview

050-3801-3651 has accumulated 110,000+ lookups on phone-number search sites and is reported as a number used to relay two-factor authentication codes. It is suspected of being misused to relay codes stolen through phishing.

Reported tactics

  • The attacker uses login credentials entered at a phishing site to attempt login at the real site
  • The two-factor code sent from the real site is forwarded to the victim through this number
  • If the victim enters the code, the attacker gains access to the account

If a two-factor code arrives from this number while you are not actively logging in, a third party is likely attempting unauthorized access to your account.

How to handle this

Ignore unexpected codes

If a code arrives when you didn't initiate a login, it's an unauthorized-access attempt. Don't enter the code; change your password immediately.

Where to report or get help

  • The support desk of the service in question
  • IPA Safe Consultation Desk: 03-5978-7509

Frequently Asked Questions

I got an auth code from 050-3801-3651. What should I do?

If you didn't initiate a login, it's a third-party unauthorized-access attempt. Don't enter the code; change your password immediately.

What is a 2FA relay attack?

A tactic where attackers log in to the real site using credentials stolen via phishing, then forward the authentication code to the victim.

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