I'm restricting bucket access to my VPC Endpoints, I have a bucket say test-bucket, I have added the below policy to enable the access to be restricted to only through the VPC Endpoints:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "Access From Dev, QA Account",
"Effect": "Deny",
"NotPrincipal": {
"AWS": arn:aws:iam::x:root"
},
"Action": [
"s3:GetBucketLocation",
"s3:GetObject",
"s3:ListBucket"
],
"Resource": [
"arn:aws:s3:::test-bucket",
"arn:aws:s3:::test-bucket/*"
],
"Condition": {
"StringNotEquals": {
"aws:sourceVpce": [
"vpce-1234",
"vpce-1235"
]
}
}
}
This policy block console, awscli access to all users, provides only instances in the VPC to gain access to s3 bucket, i have a user group called D which consist of 40 users, I cannot add the group arn to principal as AWS doesn't support it, but it is tedious to add all the 40 users to the bucket policy. We are denying all traffic as we are making our objects Public, as this bucket is used as a yum repo and have to be available over https for the instances to download during a yum install/update. Kindly advice on how to give access using that users group D or is there any way around to provide users access ?
The group is not a principal which means you would be limited to the arn of the IAM user in this specific condition.
As a workaround you could create an IAM role that is able to be assumed either through the console or via the CLI. Then ensure that the S3 bucket policy specified the arn of the IAM role instead. Finally allow the users in the group to assume the IAM role.
Related
I have an Amazon AWS account and I'm using Amazon S3.
I'd like to give access to specific people to a Amazon S3 bucket.
Here's what I'd like to do :
Amazon AWS: Access limited to my account
Amazon S3: Access limited to my account
Bucket "website-photos": Access authorized to 3 people that will be able to read and write in the bucket through AWS management console.
Files in the bucket "website-photos": Public can read them.
How can I setup this config?
Just create an IAM policy and attach to the users you want to give access:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "ListObjectsInBucket",
"Effect": "Allow",
"Action": ["s3:ListBucket"],
"Resource": ["arn:aws:s3:::bucket-name"]
},
{
"Sid": "AllObjectActions",
"Effect": "Allow",
"Action": "s3:*Object",
"Resource": ["arn:aws:s3:::bucket-name/*"]
}
]
}
See: Amazon S3: Allows Read and Write Access to Objects in an S3 Bucket - AWS Identity and Access Management
The general approach is:
If you want something to be "public" (accessible by anyone), then use a Bucket Policy
If you want to only assign permissions to a specific IAM User, then attach a policy to the IAM User
If you want to only assign permissions to a group of IAM Users, then create an IAM Group, attach a policy and assign the group to the desired IAM Users
There's some CSV data files I need to get in S3 buckets belonging to a series of AWS accounts belonging to a third-party; the owner of the other accounts has created a role in each of the accounts which grants me access to those files; I can use the AWS web console (logged in to my own account) to switch to each role and get the files. One at a time, I switch to the role for each of the accounts and then get the files for that account, then move on to the next account and get those files, and so on.
I'd like to automate this process.
It looks like AWS Glue can do this, but I'm having trouble with the permissions.
What I need it to do is create permissions so that an AWS Glue crawler can switch to the right role (belonging to each of the other AWS accounts) and get the data files from the S3 bucket of those accounts.
Is this possible and if so how can I set it up? (e.g. what IAM roles/permissions are needed?) I'd prefer to limit changes to my own account if possible rather than having to ask the other account owner to make changes on their side.
If it's not possible with Glue, is there some other easy way to do it with a different AWS service?
Thanks!
(I've had a series of tries but I keep getting it wrong - my attempts are so far from being right that there's no point in me posting the details here).
Yes, you can automate your scenario with Glue by following these steps:
Create an IAM role in your AWS account. This role's name must start with AWSGlueServiceRole but you can append whatever you want. Add a trust relationship for Glue, such as:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": {
"Service": "glue.amazonaws.com"
},
"Action": "sts:AssumeRole"
}
]
}
Attach two IAM policies to your IAM role. The AWS managed policy named AWSGlueServiceRole and a custom policy that provides the access needed to all the target cross account S3 buckets, such as:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "BucketAccess",
"Effect": "Allow",
"Action": [
"s3:ListBucket",
"s3:GetBucketLocation"
],
"Resource": [
"arn:aws:s3:::examplebucket1",
"arn:aws:s3:::examplebucket2",
"arn:aws:s3:::examplebucket3"
]
},
{
"Sid": "ObjectAccess",
"Effect": "Allow",
"Action": "s3:GetObject",
"Resource": [
"arn:aws:s3:::examplebucket1/*",
"arn:aws:s3:::examplebucket2/*",
"arn:aws:s3:::examplebucket3/*"
]
}
]
}
Add S3 bucket policies to each target bucket that allows your IAM role the same S3 access that you granted it in your account, such as:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "BucketAccess",
"Effect": "Allow",
"Principal": {
"AWS": "arn:aws:iam::your_account_number:role/AWSGlueServiceRoleDefault"
},
"Action": [
"s3:ListBucket",
"s3:GetBucketLocation"
],
"Resource": "arn:aws:s3:::examplebucket1"
},
{
"Sid": "ObjectAccess",
"Effect": "Allow",
"Principal": {
"AWS": "arn:aws:iam::your_account_number:role/AWSGlueServiceRoleDefault"
},
"Action": "s3:GetObject",
"Resource": "arn:aws:s3:::examplebucket1/*"
}
]
}
Finally, create Glue crawlers and jobs in your account (in the same regions as the target cross account S3 buckets) that will ETL the data from the cross account S3 buckets to your account.
Using the AWS CLI, you can create named profiles for each of the roles you want to switch to, then refer to them from the CLI. You can then chain these calls, referencing the named profile for each role, and include them in a script to automate the process.
From Switching to an IAM Role (AWS Command Line Interface)
A role specifies a set of permissions that you can use to access AWS
resources that you need. In that sense, it is similar to a user in AWS
Identity and Access Management (IAM). When you sign in as a user, you
get a specific set of permissions. However, you don't sign in to a
role, but once signed in as a user you can switch to a role. This
temporarily sets aside your original user permissions and instead
gives you the permissions assigned to the role. The role can be in
your own account or any other AWS account. For more information about
roles, their benefits, and how to create and configure them, see IAM
Roles, and Creating IAM Roles.
You can achieve this with AWS lambda and Cloudwatch Rules.
You can create a lambda function that has a role attached to it, lets call this role - Role A, depending on the number of accounts you can either create 1 function per account and create one rule in cloudwatch to trigger all functions or you can create 1 function for all the accounts (be cautious to the limitations of AWS Lambda).
Creating Role A
Create an IAM Role (Role A) with the following policy allowing it to assume the role given to you by the other accounts containing the data.
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "Stmt1509358389000",
"Effect": "Allow",
"Action": [
"sts:AssumeRole"
],
"Resource": [
"",
"",
....
"
]// all the IAM Role ARN's from the accounts containing the data or if you have 1 function for each account you can opt to have separate roles
}
]
}
Also you will need to make sure that a trust relationship with all the accounts are present in Role A's Trust Relationship policy document.
Attach Role A to the lambda functions you will be running. you can use serverless for development.
Now your lambda function has Role A attached to it and Role A has sts:AssumeRole permissions over the role's created in the other accounts.
Assuming that you have created 1 function for 1 account in you lambda's code you will have to first use STS to switch to the role of the other account and obtain temporary credentials and pass these to S3 options before fetching the required data.
if you have created 1 function for all the accounts you can have the role ARN's in an array and iterate over it, again when doing this be aware of the limits of AWS lambda.
I have a static website hosted on S3, I have set all files to be public.
Also, I have an EC2 instance with nginx that acts as a reverse proxy and can access the static website, so S3 plays the role of the origin.
What I would like to do now is set all files on S3 to be private, so that the website can only be accessed by traffic coming from the nginx (EC2).
So far I have tried the following. I have created and attached a new policy role to the EC2 instance with
Policies Granting Permission: AmazonS3ReadOnlyAccess
And have rebooted the EC2 instance.
I then created a policy in my S3 bucket console > Permissions > Bucket Policy
{
"Version": "xxxxx",
"Id": "xxxxxxx",
"Statement": [
{
"Sid": "xxxxxxx",
"Effect": "Allow",
"Principal": {
"AWS": "arn:aws:iam::XXXXXXXXXX:role/MyROLE"
},
"Action": "s3:GetObject",
"Resource": "arn:aws:s3:::XXX-bucket/*"
}
]
}
As principal I have set the ARN I got when I created the role for the EC2 instance.
"Principal": {
"AWS": "arn:aws:iam::XXXXXXXXXX:role/MyROLE"
},
However, this does not work, any help is appreciated.
If the Amazon EC2 instance with nginx is merely making generic web requests to Amazon S3, then the question becomes how to identify requests coming from nginx as 'permitted', while rejecting all other requests.
One method is to use a VPC Endpoint for S3, which allows direct communication from a VPC to Amazon S3 (rather than going out an Internet Gateway).
A bucket policy can then restrict access to the bucket such that it can only be accessed via that endpoint.
Here is a bucket policy from Example Bucket Policies for VPC Endpoints for Amazon S3:
The following is an example of an S3 bucket policy that allows access to a specific bucket, examplebucket, only from the VPC endpoint with the ID vpce-1a2b3c4d. The policy uses the aws:sourceVpce condition key to restrict access to the specified VPC endpoint.
{
"Version": "2012-10-17",
"Id": "Policy",
"Statement": [
{
"Sid": "Access-to-specific-VPCE-only",
"Action": "s3:*",
"Effect": "Allow",
"Resource": ["arn:aws:s3:::examplebucket",
"arn:aws:s3:::examplebucket/*"],
"Condition": {
"StringEquals": {
"aws:sourceVpce": "vpce-1a2b3c4d"
}
},
"Principal": "*"
}
]
}
So, the complete design would be:
Object ACL: Private only (remove any current public permissions)
Bucket Policy: As above
IAM Role: Not needed
Route Table configured for VPC Endpoint
Permissions in Amazon S3 can be granted in several ways:
Directly on an object (known as an Access Control List or ACL)
Via a Bucket Policy (which applies to the whole bucket, or a directory)
To an IAM User/Group/Role
If any of the above grant access, then the object can be accessed publicly.
Your scenario requires the following configuration:
The ACL on each object should not permit public access
There should be no Bucket Policy
You should assign permissions in the Policy attached to the IAM Role
Whenever you have permissions relating to a User/Group/Role, it is better to assign the permission in IAM rather than on the Bucket. Use Bucket Policies for general access to all users.
The policy on the Role would be:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "AllowBucketAccess",
"Effect": "Allow",
"Action": [
"s3:GetObject"
],
"Resource": [
"arn:aws:s3:::my-bucket/*"
]
}
]
}
This policy is directly applied to the IAM Role, so there is no need for a principal field.
Please note that this policy only allows GetObject -- it does not permit listing of buckets, uploading objects, etc.
You also mention that "I have set all files to be public". If you did this by making each individual object publicly readable, then anyone will still be able to access the objects. There are two ways to prevent this -- either remove the permissions from each object, or create a Bucket Policy with a Deny statement that stops access, but still permits the Role to get access.
That's starting to get a bit tricky and hard to maintain, so I'd recommend removing the permissions from each object. This can be done via the management console by editing the permissions on each object, or by using the AWS Command-Line Interface (CLI) with a command like:
aws s3 cp s3://my-bucket s3://my-bucket --recursive --acl private
This copies the files in-place but changes the access settings.
(I'm not 100% sure whether to use --acl private or --acl bucket-owner-full-control, so play around a bit.)
In our environment, all IAM user accounts are assigned a customer-managed policy that grants read-only access to a lot of AWS services. Here's what I want to do:
Migrate a sql server 2012 express database from on-prem to a RDS instance
Limit access to the S3 bucket containing the database files
Here's the requirements according to AWS:
A S3 bucket to store the .bak database file
A role with access to the bucket
SQLSERVER_BACKUP_RESTORE option attached to RDS instance
So far, I've done the following:
Created a bucket under the name "test-bucket" (and uploaded the .bak file here)
Created a role under the name "rds-s3-role"
Created a policy under the name "rds-s3-policy" with these settings:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"s3:ListBucket",
"s3:GetBucketLocation"
],
"Resource": "arn:aws:s3:::test-bucket/"
},
{
"Effect": "Allow",
"Action": [
"s3:GetObjectMetaData",
"s3:GetObject",
"s3:PutObject",
"s3:ListMultipartUploadParts",
"s3:AbortMultipartUpload"
],
"Resource": "arn:aws:s3:::test-bucket/*"
}
]
}
Assigned the policy to the role
Gave the AssumeRole permissions to the RDS service to assume the role created above
Created a new option group in RDS with the SQLSERVER_BACKUP_RESTORE option and linked it to my RDS instance
With no restrictions on my S3 bucket, I can perform the restore just fine; however, I can't find a solid way of restricting access to the bucket without hindering the RDS service from doing the restore.
In terms of my attempts to restrict access to the S3 bucket, I found a few posts online recommending using an explicit Deny statement to deny access to all types of principals and grant access based on some conditional statements.
Here's the contents of my bucket policy:
{
"Version": "2012-10-17",
"Id": "Policy1486769843194",
"Statement": [
{
"Sid": "Stmt1486769841856",
"Effect": "Deny",
"Principal": "*",
"Action": "s3:*",
"Resource": [
"arn:aws:s3:::test-bucket",
"arn:aws:s3:::test-bucket/*"
],
"Condition": {
"StringNotLike": {
"aws:userid": [
"<root_id>",
"<user1_userid>",
"<user2_userid>",
"<user3_userid>",
"<role_roleid>:*"
]
}
}
}
]
}
I can confirm the bucket policy does restrict access to only the IAM users that I specified, but I am not sure how it treats IAM roles. I used the :* syntax above per a document I found on the aws forums where the author stated the ":*" is a catch-all for every principal that assumes the specified role.
The only thing I'm having a problem with is, with this bucket policy in place, when I attempt to do the database restore, I get an access denied error. Has anyone ever done something like this? I've been going at it all day and haven't been able to find a working solution.
The following, admittedly, is guesswork... but reading between the lines of the somewhat difficult to navigate IAM documentation and elsewhere, and taking into account the way I originally interpreted it (incorrectly), I suspect that you are using the role's name rather than the role's ID in the policy.
Role IDs look similar to AWSAccessKeyIds except that they begin with AROA....
For the given role, find RoleId in the output from this:
$ aws iam get-role --role-name ROLE-NAME
https://aws.amazon.com/blogs/security/how-to-restrict-amazon-s3-bucket-access-to-a-specific-iam-role/
Use caution when creating a broad Deny policy. You can end up denying s3:PutBucketPolicy to yourself, which leaves you in a situation where your policy prevents you from changing the policy... in which case, your only recourse is presumably to persuade AWS support to remove the bucket policy. A safer configuration would be to use this to deny only the object-level permissions.
I am looking to lock down an S3 bucket for security purposes - i'm storing deployment images in the bucket.
What I want to do is create a bucket policy that supports anonymous downloads over http only from EC2 instances in my account.
Is there a way to do this?
An example of a policy that I'm trying to use (it won't allow itself to be applied):
{
"Statement": [
{
"Effect": "Allow",
"Principal": {
"AWS": "*"
},
"Action": "s3:GetObject",
"Resource": "arn:aws:s3:::[my bucket name]",
"Condition": {
"ArnEquals": {
"aws:SourceArn": "arn:aws:ec2:us-east-1:[my account id]:instance/*"
}
}
}
]
}
Just to clarify how this is normally done. You create a IAM policy, attach it to a new or existing role, and decorate the ec2 instance with the role. You can also provide access through bucket policies, but that is less precise.
Details below:
S3 buckets are default deny except for my the owner. So you create your bucket and upload the data. You can verify with a browser that the files are not accessible by trying https://s3.amazonaws.com/MyBucketName/file.ext. Should come back with error code "Access Denied" in the xml. If you get an error code of "NoSuchBucket", you have the url wrong.
Create an IAM policy based on arn:aws:iam::aws:policy/AmazonS3ReadOnlyAccess. Starts out looking like the snip below. Take a look at the "Resource" key, and note that it is set to a wild card. You just modify this to be the arn of your bucket. You have to do one for the bucket and its contents so it becomes: "Resource": ["arn:aws:s3:::MyBucketName", "arn:aws:s3:::MyBucketName/*"]
Now that you have a policy, what you want to do is to decorate your instances with a IAM Role that automatically grants it this policy. All without any authentication keys having to be in the instance. So go to Role, create new role, make an Amazon EC2 role, find the policy you just created, and your Role is ready.
Finally you create your instance, and add the IAM role you just created. If the machine already has its own role, you just have to merge the two roles into a new one for the machine. If the machine is already running, it wont get the new role until you restart.
Now you should be good to go. The machine has the rights to access the s3 share. Now you can use the following command to copy files to your instance. Note you have to specify the region
aws s3 cp --region us-east-1 s3://MyBucketName/MyFileName.tgz /home/ubuntu
Please Note, the term "Security through obscurity" is only a thing in the movies. Either something is provably secure, or it is insecure.
I used something like
{
"Version": "2012-10-17",
"Id": "Allow only My VPC",
"Statement": [
{
"Sid": "Allow only My VPC",
"Effect": "Allow",
"Principal": "*",
"Action": "s3:GetObject", "s3:ListBucket",
"Resource": [
"arn::s3:::{BUCKET_NAME}",
"arn::s3:::{BUCKET_NAME}/*"
],
"Condition": {
"StringLike": {
"aws:sourceVpc": "{VPC_ID}" OR "aws:sourceVpce": "{VPCe_ENDPOINT}"
}
}
}
]
}