Deciphering The Legitimacy of an Email: Sender and Receiver

Cybercriminals love email not only because it can be used to easily manipulate potential victims, but because it is also very easy to spoof.  Cybercriminals will set up fake email accounts and corresponding addresses in order to make the message appear to be legitimate.  Spoofed emails are difficult to identify without a careful examination of email message. Specifically the email “header.”

Each email message contains two “headers.”  The first is the visible header, which one can see at the top of any email message. The visible header contains the From,  To,  Date,  CC,  and Subject lines. We see visible headers everyday but never pay much attention to them. Spoofing is so easy that it does’t take a cybercriminal to manipulate  the message header to change the sender’s identify so an email looks like it is coming from someone else.

The second header is called the technical header and which I will discuss in my next post.

One way to begin deciphering the legitimacy an email is by reviewing the visible email header, starting the From: and  To: fields.

From: The Sender 

  • Do you recognize the sender’s email address? Carefully check the address since a bad guy can spoof an address similar to one you may be used to seeing. Check how the name is spelled since the address could contain one dropped or have additional characters.
  • Does the email appear to be sent from someone inside the organization but the subject and content unusual in some way? For example, a manager asking you to buy gift cards when they never asked you to do that before no do you have the authority to do so.
  • Does the sender’s email address look familiar but actually from a different domain then you are used to seeing? For example instead of Your_Boss@Your.Institution the messages comes as Your_Boss@yahoo.com.
  • Do you have no relationship with nor have had any past communications with the sender? These email cold calls may simply be “legitimate  SPAM” but may be nefarious in intent.
  • Is the message from someone you haven’t recently communicated with?
  • Is the message from someone who is a friend of a friend that you may know by name but never communicated with? Cybercriminals will often hack email addresses books and harvest such names.

To: The Recipient

Cybercriminals will send their email messages to a group of people in an attempt to get at least one to take the bait.

  • Is your address a CC on an email sent to one or more recipients you are unfamiliar with? If you don’t recognize the other recipients the criminal may have harvested an email address book from someone on which your name appears. Instead of sending individual emails they do an email blast.
  • Is there any pattern to the other the recipients such as all names starting with the same letter?

If there is any question about an email or a specific request pick up the phone and calling the person you think sent the message to confirm its legitimacy.

Deciphering The Legitimacy of an Email: The Message Header

Cybercriminals love email.  They love email not only because it can be used to manipulate potential victims but also because it is also very easy to “spoof.” Simply put, a spoofed email is one in which the address in the From field is not that of the actual sender. However, how often do we just scan our our email messages for specific names or subjects and just assume they are legitimate? Every.Single.Day. This is why the bad guys love email.

Identifying a spoofed email requires the careful examination of the  message, starting with the email “header.” Before we get into how to  examine a header it is important to understand how an email gets transmitted.

After you construct an email message and hit Send your email program (e.g. Gmail, Outlook) uploads the message to a SMTP (Simple Mail Transport Protocol) server, a computer that begins the process of transmitting the message to the intended recipient. Your message is the then relayed from SMTP server to SMTP server across the Internet to its final destination domain (e.g. gmail.com) .

When your message arrives at it’s destination domain it is stored in the recipient’s mailbox at an IMAP (Internet Message Access Protocol) or POP (Post Office Protocol ) server. This email server provides a temporary in-box where the message waits until it is fetched by an email program.

The information contained in the email header provides the details on where the message is coming from, and where it is going to, so all the servers can assist in the routing. Every email message contains two headers. The first is the visible header, which one sees at the top of any email message and contains the From,  To,  Date,  CC,  and Subject lines.

The second email header is called the technical header. The technical header is almost always hidden from view but can take a bit of digging in your email client to figure out how to make it visible. The information included in the technical header is all the – you guessed it – technical details required for routing of an email message.

Over the next few posts I will discuss details of the visible header and what to look for in the header to help decipher the legitimacy of an email. I will also discuss the technical header and how it is used by servers and SPAM filters to weed out illegitimate messages.

Email: The Cybercrime Gateway

Billions of email messages are sent each day.  The ease of use, speed of transmission, and relative anonymity of email has made it a tool for cyber criminals. One survey indicates that 91% of all cyber crime starts with an email.

Using email to commit cybercrime is almost as old as email itself. While there are many ways email can be expoited, here are the more common ones:

Phishing

The term Phishing is a generic term used to describe the very broad category of email techniques used by cybercriminals. Future posts will go to Phishing techniques in greater detail.

Scamming

Based on the centuries old Spanish Prisoner, the infamous Nigerian 419  email scam of the 1990’s is still alive and well in one form or another and is a classic phishing scam. It involves promising the potential victim share of a large sum of money, in return for an up-front payment. If someone actually makes the payment, the scammer either invents a series of further fees for the victim to pay or simply disappears.

Spoofing

A spoofed email is one that appears to originate from one source but is actually sent by another. Like Neighbor Spoofing, falsifying the name and / or email address of someone the receiver is likely to know increases the odds the person will respond or take requested action (check out funny joke in the attachment!) It is actually not too difficult to spoof an email adddress using relatively simple tools.

Spreading Trojans, Viruses and Worms

Emails are perhaps the fastest and easiest way to spread malicious code. For example, the Love Bug reached millions of computers within 36 hours back in 2000,  all thanks to email. Cybercriminals will bind the malicious code in e-greeting cards, fake virus patches, et and email them in messages which are written in a way to make the reader feel like immediate action is required.

Attachments

Attachments are a very common way to spread malicious code. The rule of thumb is to open only those attachments that you are expecting – even if coming from someone you know (remember: email address spoofing!). File names can been spoofed as well so that an attached file that is actually a computer program can look as though it is a simple word processing file. If you are unsure, contact the person and ask if they sent it.

Links

Don’t immediately click on the link(s) in emails. Keep in mind email spoofing since a message may look like it is coming from someone you know! Hover your curser over any links to double check if the destination URL is what it’s claiming to be. To be extra careful, type out URLs manually instead of clicking links.

Getting SPAM Texts? Forward them to 7726

The use of text messaging is a growing tool for marketers. Many texts are legitimate and originate from service providers you may have given your number to.  However, the number of SPAM text messages appears to be growing rapidly. According to the Federal Trade Commission, “It’s illegal to send unsolicited commercial messages to wireless devices, including cell phones and pagers, unless the sender gets your permission first.” The same would hold true for text messages that are sent from robo-callers.

If you’re receiving random messages from unknown numbers or entities it is probably illegal SPAM from someone phishing for information and trying to scam you. So, what can one do?

Report to your carrier

A little known service provided by most cell carriers is SPAM reporting. On an iPhone, select the spam message by holding it down with your finger. A menu will pop up. In the lower right, select More and then the arrow icon. This will create a new message that can be forwarded. On almost all carriers forward the message to 7726. Make sure to copy the phone number that send the message since an auto-reply may ask for it as well.  Why 7726? It spells SPAM.

Block numbers

On an iPhone, go to the offending text and press the “i” in the upper right-hand corner. That is where you will find the option to Block the number. There is no way for the robs-callers to know you’ve blocked them so they can send all the messages messages they want. There is one caveat. The blocked number can still leave a voicemail but you won’t receive a notification. You may notice voicemails piling up on you.

Resist the urge

You may feel the urge to reply to a SPAM text. Maybe you want to tell them how you feel. Maybe you love practical jokes and you want to mess around. Don’t.  Don’t even responding to their request that you reply “NO” to stop their messages. Engaging the sender in any way will make the problem worse.