Domain Spoofing – Making things difficult for an attacker
Phishing emails comes in many shapes and form. here are various forms of phishing, organizations are currently struggling with :
Types of Phishing
1. Domain Spoofing – In this type of phishing, the email’s from address indicates it has come from reputated domains like Microsoft, Google, Paypal etc and often organization’s own domain but it really has not originated from there servers. Attackers often spoof the domain to make it look like a legitimate emails from these company’s and asking recipients to do a task like verify their account to harvest credential, download and install a file which is malicious, or visit a malicious webpage.
2. Domain Impersonation – In this type of phishing, the attackers registers a similar looking domain as your organization’s or major brands Microsoft etc, For Eg If your Organization’s domain is Contoso.com, attackers would register domains like c0ntoso.com, Cont0so_.com etc and then sends out emails from these domains to your users asking them to carry out a transaction, click on URLs or open an attachment. If users are not paying attention they would never be able to differentiate between original domain name of the organization and “Typosquatted” domain attacker is sending these email from.
3. User Impersonation – In this type of phishing, attackers uses the name of top executive’s names like your CEO, Director, CFO etc and then send email to their subordinates or to the other group of employees and then ask them to carry out a high value activity. These executive’s name usually have high authority which are often not questioned and hence employees falls for it without verifying the identity or the intent of the email.
While this is not a exhaustive list, attackers also use combinations of above techniques to increase their chances of a successful exploitation.
In this post, we’ll talk about Domain Spoofing in details”:
Spoofing a domain and its reputation have been into existence for ages and with the advent of various tools and scripts it has got a lot easier to carry out this attack.
Protection against Spoofed Emails
Create a SPF record for your Organization : –
SPF or Sender Policy Framework is a authentication technique to validate if the email is actually originated from designated server of the domain or not and hence helps in detecting spoofed and forged emails.
If you are an Office 365 Email customers, you can follow these steps to create your SPF Record.
This will ensure if any attackers tries to spoof your domain to send emails to your organization or to others external parties will have their domain authentication failed.
If you are an Office 365 Exchange Online Customer, Inbuilt Exchange Online Protection by default protects from domain spoofing by redirecting all the emails to Junk Mailbox folder if the SPF or domain authentication is failed by marking them as High Spam or Spam.
You should definitely check your Anti Spam settings to see how you want Spam and High Spam emails to be treated,
Detecting a Spoofed email
Detecting a spoofed email is never so easy as the from address will have the exact domain name as you’d like it to have. So if an attacker is trying to spoof your own organization’s domain, your users will actually see the correct domain name in the ‘From’ address.
if you take a look at following example of an Spoofed email, the ‘from’ domain is actually showing as Contoso.com which is the legitimate domain of this Organization. So its not that easy to differentiate unless you are ready to dive deep into Header Analysis
Yes, you may find additional clue in the email which might seem odd and can help figure it out, you can read my previous post on finding clues for Phishing.
So lets take a look at what are the things you should look at in the email header which can help identify that this is a spoofed email.
Follow this to pull out the message headers if you are using Outlook Client.
If you are using OWA, click on the drop down menu on the right hand side and click on message details.
You may copy the message headers and then paste it to the Microsoft Message Header Analysis tool and hit analyze.
Now lets see what things you should look at:
You should find that domain Authentication like SPF = FAIL. We’ll learn more about SPF later in this post.
Since the email is not originated from the server of the domain which it says its from, the SPF will be failed.
Also Auth AS value should be showing Anonymous. which means the email is not authenticated with a credentials.
if this email actually had been sent from your domain, the Auth As value should be “Authenticated”
Create an Warning Message for all External Email – Mail Tips
Consider creating a caution message on the top of all the emails originating from external servers, You can use Exchange Online mail flow rules to create these custom notifications, More info on creating disclaimers here
“Legitimate Spoofing” ? Is that even a thing? why would a spoofing be legitimate?
Well, Yes, there are emails which could be SPF failed but still be legitimate,
No SPF Records : If you are getting an email from a organizations who have not configured and published their SPF records with their domain registrar, there is no way to authenticate them.
Cloud Hosted Email Service Provider : If your sender’s email service is hosted on a shared tenant with a cloud service provider, there are chances that the provider cannot provide individual server details for SPF configuration for each and every email tenant.
Marketing and Newsletters : Some organizations outsources their marketing email campaign to third party companies who sends emails on behalf of their clients and hence those emails would look like as Spoof however genuine.
Spoof Intelligence to rescue :
Office 365 Customers can now take a look at the Spoof Intelligence report to see the domain pairs who are sending emails to your organizations and their domain authentication is getting failed. You also have the option to configure if you are okay to have their emails coming in while their domain authentication has failed.
So if you do see a domain here which is sending legitimate emails but getting failed authentication, you can come here and mark them as “Allowed to Spoof” which will ensure optimized mail flow from them.
I hope this post helps un understanding domain Spoofing and how can we make it harder for attackers to bypass the protection.
In my next post, we’ll look at a common configuration mistake which lets these Spoofed emails coming in and getting delivered, specially if the attacker is spoofing your own domain.