I have created an IAM user (without MFA) and attached the below policy to the user. This is to make sure that the calls to the S3 use MFA. But, when I use the AccessKeys for this user via the AWS CLI, I am able to perform the S3 operation aws s3 ls with out any authorization error.
Am I doing something wrong or is it a bug in AWS?
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": "s3:*",
"Resource": "*",
"Condition": {
"BoolIfExists": {
"aws:MultiFactorAuthPresent": "true"
}
}
}
]
}
Not exactly sure why the policy statement in the OP is not working. But,
I did attach the AmazonS3FullAccess policy with one of the below policy and it behaves as expected. For the long-term credentials I am not able to perform S3 operations and for the temporary credentials when authenticated with MFA I am able to perform the S3 operations.
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Deny",
"Action": "s3:*",
"Resource": "*",
"Condition": {
"BoolIfExists": {
"aws:MultiFactorAuthPresent": "false"
}
}
}
]
}
{
"Version": "2012-10-17",
"Id": "123",
"Statement": [
{
"Effect": "Deny",
"Resource": "*",
"Action": "s3:*",
"Condition": {
"Null": {
"aws:MultiFactorAuthAge": true
}
}
}
]
}
You are using Allow, but you should be using Deny as explained in AWS docs. Example:
{
"Version": "2012-10-17",
"Id": "123",
"Statement": [
{
"Sid": "",
"Effect": "Deny",
"Principal": "*",
"Action": "s3:*",
"Resource": "arn:aws:s3:::DOC-EXAMPLE-BUCKET/taxdocuments/*",
"Condition": { "Null": { "aws:MultiFactorAuthAge": true }}
}
]
}
Read the AWS docs carefully, as you can lock yourself out of the bucket if you use Deny incorrectly.
Related
I have AWS SSO users with login like firstname.lastname.
I would like to have a policy like this
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": "ec2:SomeAction",
"Resource": ["*"],
"Condition": {
"StringEquals": {
"ec2:ressourceTag/User": "${firstname.lastname}"
}
}
},
{
"Effect": "Allow",
"Action": "ec2:DescribeInstances",
"Resource": "*"
}
]
}
Of course ${firstname.lastname} should be dynamically filled using SSO data.
It's my understanding of reference_policies_variables, that it is not straighforward.
Is there a way ?
I would like to create an SCP to enforce encryption on SNS creation. I am creating the below policy but it has not worked.
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "Statement1",
"Effect": "Deny",
"Action": [
"sns:CreateTopic"
],
"Resource": "*",
"Condition": {
"StringNotEquals": {
"attributes:KmsMasterKeyId": "alias/aws/sns"
}
}
}
]
}
I'm not sure where did you find attributes:KmsMasterKeyId condition key, but based on AWS docs, sns:CreateTopic does not support such a condition.
I would like to set a policy for a S3 bucket that is restricted to a VPC-ID(using a S3 endpoint). I have two accounts, A and B. I want a IAM user in A to access a bucket in B.
https://docs.aws.amazon.com/AmazonS3/latest/userguide/example-bucket-policies-vpc-endpoint.html
{ "Version": "2012-10-17", "Id": "Policy1415115909153", "Statement": [
{
"Sid": "Access-to-specific-VPC-only",
"Principal": "*",
"Action": "s3:*",
"Effect": "Deny",
"Resource": ["arn:aws:s3:::awsexamplebucket1",
"arn:aws:s3:::awsexamplebucket1/*"],
"Condition": {
"StringNotEquals": {
"aws:SourceVpc": "vpc-111bbb22"
}
}
} ] }
Above won't work, but following will:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": "*",
"Action": "s3:*",
"Resource": [
"arn:aws:s3:::bucket",
"arn:aws:s3:::bucket/*"
],
"Condition": {
"StringEquals": {
"aws:SourceVpc": "vpc-111111111111"
}
}
}
]
}
Feels like best practices is to use a deny policy. Anyone has an idea why and how solve it?
As pointed out you need to allow as-well. Combine both policies and it will work.
I wanted to allow all s3 actions on a particular bucket "test-bucket" for a specific role "test-role". Deny the bucket for all others. The s3 policy I have written :
{
"Version": "2012-10-17",
"Id": "Policy1601973417173",
"Statement": [
{
"Sid": "Allow role test-role",
"Effect": "Allow",
"Principal": {
"AWS": "arn:aws:iam::xxxxxxxx:role/test-role"
},
"Action": "s3:*",
"Resource": "arn:aws:s3:::test-bucket/*"
},
{
"Sid": "Deny rest",
"Effect": "Deny",
"NotPrincipal": {
"AWS": "arn:aws:iam::xxxxxxxx:role/test-role"
},
"Action": "s3:*",
"Resource": "arn:aws:s3:::test-bucket/*"
}
]
}
Even after applying the above policy, the sso users which are mapped to the role "test-role" is getting Access denied on the bucket.
Note : The AWS console shows logged in user as "Federated Login: test-role/sam#abc.com".
I have also tried the "assumed-role" options are still failing. Any help appreciated.
Try this:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Deny",
"Principal": "*",
"Action": "s3:*",
"Resource": [
"arn:aws:s3:::test-bucket",
"arn:aws:s3:::test-bucket/*"
],
"Condition": {
"StringNotLike": {
"aws:userId": [
"AIDA<udserid-1-suppressed>:*",
"AIDA<udserid-1-suppressed>",
"AIDA<udserid-2-suppressed>:*",
"AIDA<udserid-2-suppressed>",
"AIDA<udserid-n-suppressed>:*",
"AIDA<udserid-n-suppressed>",
"111111111111"
]
}
}
}
]
}
I'm new to AWS.
When I added the bucket policy in the link. I lost all control from AWS console. What should I do change policy from console again.
Restricting Access to a Specific VPC
{
"Version": "2012-10-17",
"Id": "Policy1415115909153",
"Statement": [
{
"Sid": "Access-to-specific-VPC-only",
"Principal": "*",
"Action": "s3:*",
"Effect": "Deny",
"Resource": ["arn:aws:s3:::examplebucket",
"arn:aws:s3:::examplebucket/*"],
"Condition": {
"StringNotEquals": {
"aws:sourceVpc": "vpc-111bbb22"
}
}
}
]
}