Email spoofing is the faking of email addresses to disguise who is sending the email to you. This is often used by people sending spam and malware in an attempt to fool you into reading their advertisements or into opening the attachments and infecting your computer, especially with ransomware.
Because the core protocols for email do not prevent it, it is easy for someone to send you an email using a fake address for the sender. This can be done to fool you into opening the attachments or to try to fool spam filters into letting the email through to you.
A common trick is to use the recipient's email address as the sender's as well, in other words the email will appear to come from you. This is used to fool spam filters as most people don't filter out their own address, but it is a easy-to-recognize indication that you are dealing with a spoofed address.
So where is it really coming from?
Emails on their own are safe to open, although their attachments may not be.
If you want to find out where the email is really coming from you need to check the email headers ("show original"), as shown here in Zimbra, NCF's webmail interface:
Here is an example of a set of email headers from a spoofed email:
Return-Path: firstname.lastname@example.org Received: from localhost (LHLO mail.ncf.ca) (127.0.0.1) by melkor.ncf.ca with LMTP; Wed, 16 Sep 2015 19:08:57 -0400 (EDT) Received: from mail.ncf.ca (localhost [127.0.0.1]) by mail.ncf.ca (Postfix) with ESMTP id A8607A0547 for <email@example.com>; Wed, 16 Sep 2015 19:08:55 -0400 (EDT) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on melkor.ncf.ca X-Spam-Level: X-Spam-Status: No, score=-0.0 required=6.0 tests=BAYES_00,FSL_BULK_SIG, HTML_IMAGE_ONLY_32,HTML_MESSAGE,PYZOR_CHECK,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2,T_REMOTE_IMAGE autolearn=no autolearn_force=no version=3.4.0 X-Spam-Virus: No Received: from mx1.ncf.ca (pallando.ncf.ca [188.8.131.52]) by mail.ncf.ca (Postfix) with ESMTP id 942A5A051C for <firstname.lastname@example.org>; Wed, 16 Sep 2015 19:08:55 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.9.1 mail.ncf.ca 942A5A051C Received: from mx1.ncf.ca (localhost [127.0.0.1]) by mx1.ncf.ca (Postfix) with ESMTP id 73766BEE75 for <email@example.com>; Wed, 16 Sep 2015 19:08:55 -0400 (EDT) X-Greylist: delayed 420 seconds by postgrey-1.34 at pallando; Wed, 16 Sep 2015 19:08:55 EDT Received: from smtpg-pc.aruba.it (smtp217-pc.aruba.it [184.108.40.206]) by mx1.ncf.ca (Postfix) with ESMTP id 0D616BEE7C for <firstname.lastname@example.org>; Wed, 16 Sep 2015 19:08:54 -0400 (EDT) Received: from WORLDST-UQ3K9Q0 ([220.127.116.11]) by smtpcm2-pc.aruba.it with bizsmtp id Hz0g1r0094yo4K101z1GXd; Thu, 17 Sep 2015 01:01:54 +0200
The "received" sections show the IP addresses which the mail has travelled through and ultimately originates from. The IP addresses in the header are shown in bold to make them stand out. Because the bottom one is the originator, it can now be traced to see where it comes from.
Tracing IP addresses
Tracing IP addresses is fairly easy using tools like whois on Linux. They can also be traced through the websites of the IP registration authorities:
- ARIN (North America)
- RIPE NCC (Europe, the Middle East and Central Asia)
- APNIC (Asia Pacific)
- LACNIC (Latin American and Caribbean)
- AfriNIC (Africa)
- IP-adress.com (sic)
If an address is not found in one registry, it will probably be in another one.
In the case of the header example above the IP address 18.104.22.168 traces to Telefonica de Argentina in Buenos Aires, Argentina, so you can be sure it did not originate with NCF and that the return address is spoofed.
Delete it, it is spam, but at least you are now sure that it is.
Volunteer Dave - A Spoofing Story
An informative narrative written by one of our volunteers and his saga to expose spoofers when he found they were sending mail out from his address.
Someone is "Spoofing" your email address or has "hijacked" your email account. Please review the following for advice on what you can do to minimize the occurrences. Please try the suggestions and get back to us if you have further questions.
What’s worse than getting spam? Unwittingly sending it. When bogus and probably malware-laden advertising goes out in your name, you look bad. And you get flooded with bounced messages from dead addresses that some crook attempted to spam in your name.
The good news: You’re not sending out spam. Neither is your computer or your IP address. But the bad news can still be pretty bad.
If spam is going out from your email address, the address has been either spoofed or hijacked. Either way, the spam isn’t going out from your computer, and probably not from the criminal’s computer, either. It’s probably going out from an unknowing victim’s malware-infected PC.
Spoofing an email address is, in a sense, forging it. The criminal sends out mail with your From address, even though they have no access to your account.
There’s really no solution to spoofing. Fortunately, for their own reasons, cybercrooks tend to change spoofed addresses frequently. The annoyance will disappear soon.
Hijacking is worse. In this case, the criminal takes control of your account. They can read your mail, and they can target people you know when they spam. And they can lock you out of your own account.
Fortunately, you can do something about hijacking.
As soon as you discover that your address is spamming people, try to change your password…immediately. If you succeed, you’ve fixed the problem.
But if your mail service rejects your password, the problem is serious. The hijacker has changed the password first and now controls your account.
If you’re still connected and can receive mail, try to login on another computer or using your browser’s private mode. When the login fails, try the service’s “Forgot your password” or “Need help” link. The service will email you a new password. Hopefully, you’ll get it before the bad guy.
If that fails, you’ll have to contact the mail service and discuss the problem. Here are the links for Gmail and Microsoft’s Outlook . If you’re using another service, you’ll have to find the right address yourself.
Have you been using the same password for other services? If so, change them as soon as possible.
Once you’ve got everything under control, email apologies to everyone who received, or might have received, spam apparently coming from you.
Finally, follow these steps to make sure this doesn’t happen again:
Use strong, long passwords that people can’t guess.
Use different passwords for different services, and keep track of them with a password manager.
Set up 2-step verification for your service. You should find instructions on the service’s setup or options screen.
Never email your password to anyone, and I mean anyone.
Shortly after I wrote this article, my daughter's Gmail account was hacked, and everyone she knew received messages telling them to "Click on the document below and log in with your email and password to view it." I gave her the Gmail URL above, and within a few minutes she had her account back.
Here is a link to another good article about this "From:spoofing"
- Email spoofing on Wikipedia