The answer is a bit dated. In 2017, CloudFront does offer DOS protections through AWS Shield. The Standard tier is offered free to all AWS customers, including CloudFront. For additional features, you can move up to AWS Shield Advanced. From the docs:
AWS Shield is a managed Distributed Denial of Service (DDoS)
protection service that safeguards web applications running on AWS.
AWS Shield provides always-on detection and automatic inline
mitigations that minimize application downtime and latency, so there
is no need to engage AWS Support to benefit from DDoS protection.
There are two tiers of AWS Shield - Standard and Advanced.
All AWS customers benefit from the automatic protections of AWS Shield
Standard, at no additional charge. AWS Shield Standard defends against
most common, frequently occurring network and transport layer DDoS
attacks that target your web site or applications.
For higher levels of protection against attacks targeting your web
applications running on Elastic Load Balancing (ELB), Amazon
CloudFront, and Amazon Route 53 resources, you can subscribe to AWS
Shield Advanced. In addition to the common network and transport layer
protections that come with Standard, AWS Shield Advanced provides
additional detection and mitigation against large and sophisticated
DDoS attacks, near real-time visibility into attacks, and integration
with AWS WAF, a web application firewall. AWS Shield Advanced also
gives you access to the AWS DDoS Response Team (DRT) and protection
against DDoS related spikes in your ELB, CloudFront or Route 53
charges.
AWS Shield Advanced is available globally on all Amazon CloudFront and
Amazon Route 53 edge locations. You can protect your web applications
hosted anywhere in the world by deploying Amazon CloudFront in front
of your application. Your origin servers can be Amazon S3, Amazon EC2,
Elastic Load Balancing, or a custom server outside of AWS. You can
also enable AWS Shield Advanced directly on Elastic Load Balancing in
the following AWS Regions - Northern Virginia, Oregon, Ireland, and
Tokyo.
There are also individual network policies available for CloudFront if you like to do things by hand as well.