Email Account Compromise (EAC)

Is that email that just appeared in your inbox really from who it says it's from? How certain can you be?  

Cyber thieves are using social engineering, phishing attacks and other stealthy tricks to threaten their targets into making a fraudulent financial payment. The scam works by first compromising one account, then using the trust relationship between that account and those associated with that account, like vendors and contractors, colleagues, or even clients to coerce the target into transferring money to the attacker.

These attacks are ravaging financial and lending institutions, real estate companies, and law firms, particularly in today's remote work environment.

We’ve spoken with many email users who have fallen victim to this exploit which, in many cases, led to significant losses due to resulting wire transfer fraud and reputational harm. Email Account Compromise (EAC) has been around for decades, yet a surprisingly large number of email users still do not understand how this threat works and how to recognize and protect against it. We want to provide you with everything you need to know to defend against EAC - before you fall for this deceptive, costly scam.  

How Does the EAC Scam Work?

Email Account Compromise is a sophisticated email scam in which threat actors utilize social engineering tactics designed to manipulate psychology or computer intrusion techniques to compromise an email account without the knowledge of the account owner or the victims receiving fraudulent emails from this compromised account. These exploits are typically initiated with a phishing email, where a user gets his or her email account compromised by clicking on a link, opening an attachment or having his or her account “brute-forced” - a scenario in which the intruder otherwise figures out the account owner’s email login password and tricks the account owner into giving up credentials. 

Once an email account is compromised, it’s game on for the attacker - who now has full access to the account. Malicious spam emails are often sent out to everyone in the account owner’s address book, leveraging the trust that the account owner has built with these contacts to compromise further accounts with the same deceptive techniques. Sometimes threat actors will spread out these fraudulent emails in an effort to “fly under the radar” for a longer period of time.

The proliferation of cloud platforms like Microsoft 365 and Google Workspace for business email has made EAC even more efficient and dangerous, as cyber thieves are able to open any account, test their methods until they are able to bypass default filters, and reuse these methods in attacks targeting thousands of different accounts.

EAC attacks are extremely difficult to detect and combat. In these dangerous campaigns, malicious emails are often sent directly from the compromised account owner’s computer, which has been authorized to send mail as that user. In these cases, fraudulent emails are not identified and flagged by any sender authentication protocols that the account owner has implemented because they aren’t violating any of the SPF, DKIM or DMARC rules in place. As a result, malicious emails sent in these scams “pass the test” and are delivered to victims’ inboxes where they can cause serious harm - often leading to fraudulent wire transfers.

The image below is an example of a fraudulent email sent to a client from a paralegal’s compromised account in an sophisticated EAC scam targeting the legal industry sector. It contains fileless malware designed to redirect the recipient to a fake login page when he or she clicks “Review Document”. Luckily, this email was identified and quarantined by Guardian Digital EnGarde Cloud Email Security before it reached the client’s inbox. Had the law firm not invested in an advanced, effective email security solution, this email may have led to wire fraud and further account takeovers.

slide10 phish

The following image is an email sent from a Berkshire Hathaway employee’s compromised account. The attachment is a PDF containing information that requires the victim to login to a fake Microsoft SharePoint account, where the attacker would then have the full login credentials to a Berkshire Hathaway employee’s account. This malicious email originated from the compromised account, but also passed through a Message Labs (now antispam system before it was quarantined by Guardian Digital EnGarde Cloud Email Security.

berkshire hathaway phishing mod

How Can I Tell If My Email Account Has Been Compromised?

Now that you are fully aware of the risks associated with EAC, you’re probably wondering: how can I tell if my email account has been compromised? There are several signs you should look for when it comes to recognizing EAC.

First, the inability to login to your email account is a major “red flag” that a threat actor may have changed your email password. This is often one of the first steps that a cybercriminal will take after assuming control of an email account.

You can also check your “Sent” email box to verify that the emails it contains are in fact emails that you sent. If you encounter messages that you did not send, this is a strong indicator that an attacker has gained access to your email account and is using it to send fraudulent messages in your name. 

Your IP address log can also provide insight into whether your email account has been hijacked by revealing if someone is sending emails from your account from different locations. If you check a log of your IP addresses and you see several different IP addresses listed, it could be a sign that a fraudster is logging into your email account from different locations.

Finally, your friends and acquaintances can provide valuable clues as to whether your email account has been compromised. If you receive messages asking why you’ve been sending spam or questioning the integrity of your communications, it is reasonable to suspect that your account is under the control of a threat actor.

What Should I Do If My Email Account Has Been Compromised?

Knowing what to do in the event that your email account is compromised and acting fast are imperative in minimizing - and hopefully reversing - the damage that is done. If you realize that your email account has been hijacked you should immediately:

  • Notify law enforcement.
  • Contact your financial institution if you suspect or have discovered a fraudulent wire transfer.
  • Request that your bank reach out to the financial institution where the fraudulent transfer was sent.
  • File a complaint at, regardless of monetary loss. Provide any relevant information in your complaint and identify that your complaint pertains to the EAC scam.
  • Change any password that is the same as your email password.
  • Send a concise email explaining what happened and apologizing for any inconvenience to your contacts.

Tips & Advice for Recognizing and Defending Against Email Account Compromise

While EAC is a challenging scam to detect and stop, users should take steps to protect themselves and their contacts from EAC by engaging in these best practices:

  • Do not click on links, open attachments or interact in any way with emails from unknown addresses.
  • Be aware of small changes in email addresses that mimic legitimate email addresses.
  • Question any changes to wire transfer instructions by contacting the associated parties through a known avenue.
  • Have a dual step process in place for wire transfers.
  • Know your customer. Be aware of your client’s typical wire transfer activity and question any suspicious behavior.
  • Think before you click! Take adequate time to thoroughly evaluate each email you receive before interacting with that email. 
  • Critically Important: Implement a proactive, fully-supported cloud email security solution capable of detecting and blocking EAC scams and other advanced email exploits. This is the only way to ensure the safety and legitimacy of ALL emails that reach your inbox.

Is your business prepared to repel spear phishing, ransomware, EAC and other malicious threats? Use our free Email Risk Assessment Toolkit to understand your email risk profile and receive individualized advice on how you can improve your email security strategy to prevent attacks and breaches. 

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