Amazon Linux AMI Security Advisory: ALAS-2017-895
Advisory Release Date: 2017-09-14 22:32 Pacific
The default umask value is set to 022 to address a privilege escalation security vulnerability.
- Run yum update aws-cfn-bootstrap to update your system.
- Update the AWS::CloudFormation::Init metadata section of your template, specifically the entries listed under the files key, to explicitly specify the mode field as documented at http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-init.html . We recommend setting the mode to explicitly disable permissions for non-owners. Alternatively, you can also choose to explicitly change the mode of the files listed in your template, by directly logging on to the instance.
- Restart the cfn-hup process: service cfn-hup restart