Amazon Elastic Load Balancing is used to manage traffic on a fleet of Amazon EC2 instances, distributing traffic to instances across all availability zones within a region. Elastic Load Balancing has all the advantages of an on-premises load balancer, plus several security benefits:
Takes over the encryption and decryption work from the Amazon EC2 instances and manages it centrally on the load balancer
Offers clients a single point of contact, and can also serve as the first line of defense against attacks on your network
When used in an Amazon VPC, supports creation and management of security groups associated with your Elastic Load Balancing to provide additional networking and security options
Supports end-to-end traffic encryption using TLS (previously SSL) on those networks that use secure HTTP (HTTPS) connections. When TLS is used, the TLS server certificate used to terminate client connections can be managed centrally on the load balancer, rather than on every individual instance.
Reference:
http://d0.awsstatic.com/whitepapers/Security/AWS%20Security%20Whitepaper.pdf