Requirement text: SI.3.220: Utilize sandboxing to detect or block potentially malicious email.
DISCUSSION FROM SOURCE: CIS CONTROLS V7.1
Minimize the attack surface and the opportunities for attackers to manipulate human
behavior through their interaction with web browsers and email systems.
Web browsers and email clients are very common points of entry and attack because of their
technical complexity, flexibility, and their direct interaction with users and with other
systems and websites. Content can be crafted to entice or spoof users into taking actions
that greatly increase risk and allow introduction of malicious code, loss of valuable data, and
other attacks. Since these applications are the main means that users interact with untrusted
environments, these are potential targets for both code exploitation and social engineering.
This practice is based on the following CIS control:
7.10 Use sandboxing to analyze and block inbound email attachments with malicious
behavior.
CMMC CLARIFICATION
You create an email sandbox by implementing an isolated environment to execute an
attached file or linked URL. Before allowing attachments or links to be opened on the
production network, they are executed within the sandbox and their behavior is observed.
By opening these files or links in a protected environment, the system detects malicious
activity before it is introduced into the network.
Example
You are in charge of IT operations for your organization. Part of your role is to verify all
attachments and URL links in company emails. To do this, you set-up an isolated
environment, or email sandbox, to execute or open all email attachments before allowing
them on your network. You use the email sandbox to observe what happens when the
attachment or link opens. By testing these files in a sandbox, you are able to prevent the
entry of malicious content through email attachments or URL links. You only allow emails
with attachments or URL links through once they have been tested and determined to be
safe.
References
• CIS Controls v7.1 7.10
• NIST SP 800-53 Rev 4 SC-44