If a phishing attempt is successful and a threat actor gains access to an employee’s email account, it is common for the compromised email account to be used for internal phishing. Some malware variants also allow threat actors to hijack email accounts and send malware internally, adding a copy of the malware to a message thread to make it appear that a file was attached in response to a past email conversation.
There are several different scenarios where these types of attacks will occur such as business email compromise attacks to gain access to an email account that can be used for the scam – a CEO, executive, HR, or IT department account for example; to distribute malware extensively to compromise as many accounts as possible; to gain access to multiple email accounts, or to compromise multiple accounts to gain access to sensitive data.
In industries where data breach reporting is mandatory, such as in healthcare in the United States, email account breaches are regularly reported where unauthorized activity is detected in a single email account, and the subsequent investigation reveals multiple employee email accounts have been compromised through internal phishing.
Internal phishing attempts are much harder to identify than phishing attempts from external email accounts. Even when email security solutions incorporate outbound scanning, these phishing attempts are often not recognized as malicious as the emails are sent from a trusted account. The recipients of these emails are also much more likely to trust an internal email than an external email from an unknown sender and open the email, click a link, or open a shared file.
Attackers may also spoof an internal email account. It is easy to find out the format used by a company for their emails, and names can be found on professional networking sites. A good email security solution should be able to identify these spoofed emails, but if they arrive in an inbox, an employee may be fooled into thinking that the email is a genuine internal email.
It is important for businesses to take steps to combat internal phishing as it is a common weak point in email defenses. Unfortunately, there is no single technical control that can protect against these phishing attempts. What is required is a combination of measures to provide layered protection. With layered security, if one measure fails to protect against a threat, others are in places that can thwart the attempt.
The best place to start is with a technical measure to identify and block these phishing threats. Spam filter software naturally needs to have inbound as well as outbound scanning; however, standard checks such as reputation scans are not enough. An email security solution should have AI and machine learning capabilities for assessing how emails deviate from standard emails sent internally and for in-depth analysis of message content. Link scanning is also important, with URL rewriting to identify the true destination of embedded URLs, OLE detection, and email sandboxing to identify malicious attachments – not just malware but also malicious links in email attachments.
Security awareness training is vital as employees may not be aware of threats they are likely to encounter. Security awareness training should include internal phishing and employees should be made aware that they should not automatically trust internal emails as they may not be what they seem. Security awareness training should be accompanied by phishing simulations, including simulated phishing attempts from internal email accounts. These will give employees practice in identifying phishing and security teams will learn how susceptible the workforce is and can then take steps to address the problem.
Multi-factor authentication is required. If a phishing attempt is not identified by either a security solution or the employee, and the employee responds and divulges their credentials, they can be used by the threat actor to access the employee’s email account. Multi-factor authentication protects against this by requiring another factor – in addition to a password – to be provided. The most robust form of MFA is phishing-resistant MFA, although any form of MFA is better than none.
TitanHQ can help protect against phishing attacks of all types through the SpamTitan cloud-based spam filtering service, the PhishTitan anti-phishing solution for M365, and the SafeTitan Security awareness training and phishing simulation platform.
The engine that powers SpamTitan and PhishTitan has an exceptional phishing catch rate, including internal phishing attempts. The engine incorporates AI- and machine learning algorithms that can detect novel phishing attempts and emails that deviate from the normal emails sent internally, as well as OLE detection, URL rewriting, and email sandboxing for catching novel malware and phishing threats.
The SafeTitan Security awareness training platform includes an extensive library of training content to teach security best practices, eradicate risky behaviors, and train employees on how to recognize an extensive range of threats. The phishing simulator makes it easy to conduct internal phishing tests on employees to test knowledge and give employees practice at identifying email threats. Usage data shows the platform can reduce employee susceptibility to phishing attempts by up to 80%.
For more information about improving your phishing defenses, speak with TitanHQ today.