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Comment by mike-cardwell

8 years ago

Considering how easy email is to spoof, why bother using a unicode domain which is only similar to the target domain? Why not just use the real domain instead?

Spoofing isnt so easy for gmail and yahoo inboxes. Some web-clients warn of a return path too. For sophisticated spoofing and phishing unicode domains are helpful. Plus, spoofing emails is just a small attack vector.

  • Spoofing is trivially easy for gmail and yahoo. Here's me spoofing an email from fakeaddress@ycombinator.com to my gmail address:

      mike@blob:~$ telnet gmail-smtp-in.l.google.com 25
      Trying 66.102.1.26...
      Connected to gmail-smtp-in.l.google.com.
      Escape character is '^]'.
      220 mx.google.com ESMTP 19si14686133wmr.1 - gsmtp
      EHLO whatever
      250-mx.google.com at your service, [164.132.228.175]
      250-SIZE 157286400
      250-8BITMIME
      250-STARTTLS
      250-ENHANCEDSTATUSCODES
      250-PIPELINING
      250-CHUNKING
      250 SMTPUTF8
      MAIL FROM:<fakeaddress@ycombinator.com>
      250 2.1.0 OK 19si14686133wmr.1 - gsmtp
      RCPT TO:<*****@gmail.com>
      250 2.1.5 OK 19si14686133wmr.1 - gsmtp
      DATA
      354  Go ahead 19si14686133wmr.1 - gsmtp
      From: "Fake Address" <fakeaddress@ycombinator.com>
      To: *****@gmail.com
      Subject: This is a spoofed email
    
      Spoof spoof spoof
    
      --
      Spoofy McSpoof
      .
      250 2.0.0 OK 1492497764 19si14686133wmr.1 - gsmtp
    

    Email was delivered fine. Straight into the Inbox (not the spam folder). Even though ycombinator.com has strict SPF records which don't include my IP.

    The only clue is, in the web interface Google displays a grey octagon with a red question mark inside it next to the sender address. And when you hover over that a tooltip says:

    "Gmail couldn't verify that ycombinator.com actually sent this message (and not a spammer)"

    So yeah. I would dispute "Spoofing isnt so easy for gmail and yahoo inboxes" - They're as shit as everyone else.

  • A lot of email clients give a warning "this email might be spoofed". The good ones are more likely to send you straight to spam.

    Still, most people are unable to confirm the origin of an email. The warning, if any, is likely to be ignored.