In the suggested policy `ec2:CopyImage` was listed twice.
I've also sorted alphabetically to make it easier for somebody who might be recreating the policy in the AWS gui to follow along more easily.
Without the "ec2:DescribeSecurityGroups" permission, you would get the following error:
2016/10/25 16:03:28 ui: ==> aws: Creating temporary security group for this instance...
2016/10/25 16:03:28 packer.exe: 2016/10/25 16:03:28 Temporary group name: packer 580f7440-2135-068c-99b7-35595a7522d1
2016/10/25 16:03:28 ui: ==> aws: Authorizing access to port 22 the temporary security group...
2016/10/25 16:03:28 packer.exe: 2016/10/25 16:03:28 [DEBUG] Describing tempSecurityGroup to ensure it is available: sg-38e0355e
2016/10/25 16:03:29 packer.exe: 2016/10/25 16:03:29 [DEBUG] Error in querying security group UnauthorizedOperation: You are not authorized to perform this operation.
2016/10/25 16:03:29 packer.exe: status code: 403, request id: bc664eff-cc01-42c1-8408-23493c11d92d