How Does an Email Sandbox Block Malware?

You may have heard that email sandboxing is an important security feature, but how does an email sandbox block malware and why is this security feature necessary? In this post, we explain what an email sandbox is, why it is now an important element of email security, and how email sandboxes work.

An email sandbox is a secure and isolated environment where emails and their attachments are subjected to behavioral analysis. In the sandbox, malicious files and code can be safely detonated where no harm can be caused. Say an email is received that contains malicious code that is used to drop and execute ransomware on a device. Executing that code on a standard machine would initiate the process that ends with file encryption. Execute that code in an email sandbox and the malicious behavior would be detected and no harm would be caused. The email and code will then be eradicated from the email system, and the threat intelligence gathered will be sent to a global network to ensure that if the email or code is encountered again it will be immediately blocked.

Many Email Security Solutions Fail to Detect the Most Serious Threats

Traditional email security solutions perform many tests on emails to determine the likelihood of them being spam or malicious. DMARC and SPF are used to check the legitimacy of the sender, checks are performed on the reputation of an IP address/domain, and the subject, title, and body of a message are analyzed for signs of phishing and spam. Email attachments are also subject to anti-virus checks, which will identify and block all known malware variants. The result? Filtered emails contain no known spam, no known malicious hyperlinks, and no known malware.

The problem with traditional email security solutions is they are unable to detect unknown spam, phishing attempts, and malware. If a threat actor uses a previously unseen phishing email, which includes either a link to a fresh URL or a site with a good reputation, that email will most likely be delivered. If a new malware variant is sent via email, its signature will not be present in any virus or malware definition list and will similarly be delivered to an end user’s inbox. Threat intelligence is shared with email security solutions and they are constantly updated as new threats are found but there is a lag, during which time these threats will be delivered to inboxes. That is why an email sandbox is needed.

How an Email Sandbox Works

Antivirus scans will block the majority of malware, but not novel (zero-day) malware threats. When an email security solution has email sandboxing, the same checks are initially performed, and if they are passed, emails are sent to the sandbox for further analysis. The email sandbox is an isolated environment on a virtual machine that is configured to look like a genuine endpoint. As far as the threat actor is concerned, their email will have reached their intended target and the file should execute as it would on a standard machine.

In the sandbox, emails and attachments are opened and links are followed and behavior is analyzed in detail to determine if any malicious or suspicious actions occur such as a command-and-control center callbacks, attempted file encryption, or scans for running processes. If a Word document is opened that contains no hyperlinks, no macros, and no malicious scripts, and nothing suspicious occurs in the time it is present in the sandbox, the file will be determined as benign and the email will then be delivered to the intended recipient. If any malicious actions are detected, the file will be sent to a local quarantine directory where it can only be accessed by the administrator. The intelligence gathered will be sent to the global network and all users will be protected almost instantly. All copies of that message and the attachment will also be removed from the entire mail system.

Email Sandboxing and AI-Driven Threat Detection are Now Vital

Email sandboxing is now vital for email security as new malware variants are being released at an incredible rate and signature-based detection methods cannot detect new malware threats. In addition to email sandboxing, artificial intelligence must be leveraged to look for novel phishing messages, as phishing attempts are also increasing in sophistication. These AI-based checks look for messages that deviate from the typical messages received by a company, and greatly reduce the volume of spam and phishing emails that reach inboxes.

The threat landscape is constantly changing so advanced email defenses are now essential. If you are still using an email security solution without email sandboxing and AI-driven threat detection, your company is at risk. Speak to the team at TitanHQ to find out more about SpamTitan and how the award-winning email security solution can enhance your company’s security posture.