I have a sub directory under a bucket with ~7000 sub directories. And then each of those sub directories may have 1-100 files.
I need the files to be public, but I don't want anyone to be able to see the list of subdirectories, or even the list of files under a given directory.
I know I can set the ACL for the files to read-only, and then i think I can set the directory to private. But for this many files, I'm hoping there is a much easier solution?
To allow everyone to get objects, but not allow anyone to list objects, you can apply a bucket policy:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "AddPerm",
"Effect": "Allow",
"Principal": "*",
"Action": "s3:GetObject",
"Resource": [
"arn:aws:s3:::mybucket/myfolder1/*",
"arn:aws:s3:::mybucket/myfolder2/*"
]
}
]
}
Note that anyone who discovers the URL of an object can retrieve that object.
The short answer is that you don't need to do anything.
Just make your bucket public and give out links to individual files.
S3 does not actually have directories and files. It's just a key -> object mapping. The "directories" is just a convention to help people, but internally there is no structure.
2 scenarios:
Users not going through AWS auth (hitting the public URL for the object) will not be able to see the structure. Disable Read access for the Everyone group for the bucket itself, and then enable Read access for the individual files within the bucket
if you need to provide AWS credentials, only give the GetObject permission (http://docs.aws.amazon.com/AmazonS3/latest/dev/using-with-s3-actions.html)
For people with this issue that are still working with an empty bucket, what worked for me was to allow public ACLs for that bucket, from the public access configuration tab, and then pass the property { ACL: "public-read" } when uploading the file with the upload method of the SDK. This way new files have public links, but the bucket is still restricted. The bad part is that previous files remain without that public-read ACL. The documentation says you can assign ACLs in batches so maybe that's an option for non empty buckets too.
Related
I've created a unique bucket for my private files on S3. This bucket is configured to block all public access. My application is configured to upload files to this s3 bucket with no public read access and I can confirm that the permissions on the objects reflect that this is working (i.e. there are no permissions given to the public on the objects that are uploaded).
Despite all of these measures to restrict public access to these files, these files are still visible to the public. I think that my IAM settings may be overriding the ACL setting as well as the bucket settings. I'm not sure which IAM setting to change or if changes may negatively impact other parts of my application, so I'd like to restrict access to this 'private bucket' with a bucket policy if possible.
This is what I've started with for a bucket policy:
{
"Version": "2012-10-17",
"Id": "My Special Bucket Policy",
"Statement": [
{
"Sid": "DenyAccesstoAllFiles",
"Effect": "Deny",
"Principal": "*",
"Action": "s3:GetObject",
"Resource": "arn:aws:s3:::my_private_bucket/*"
}
]
}
Unfortunately, this blocks access to objects in this 'private bucket' even with a signed url.
Please note that I've been able to generate signed urls successfully. They expire in 60 seconds just as I've configured them.
Thanks for your help!
Edit: All my files are being uploaded like this:
All buckets and objects are private by default. So normally you don't need any policy on them. In your case any access is denied, because Deny always wins over any Allow:
Remember, an explicit deny in any of these policies overrides the allow.
Thus, there is no way to enable any public access to your objects due to your Deny, and no pre-signed url will change that.
Normally what you do is that you get rid of your policy, and rely on default behavior that the buckets and objects are private. In that case, the pre-signed url will work.
Two things to note:
Buckets created in AWS in default settings are always private and their objects are not accessible via their links. I think you have mixed up some links that make you believe that your objects are still visible :)
You do not need to have an explicit policy to deny all the access to
your S3 objects.
I would recommend you to remove the policy that you have attached to your bucket and then test again if the public links to your objects work (they shouldn't if your bucket is made via default settings). Once that part is clear, your pre-signed URLs should work!
I have an Amazon S3 bucket with several files with randomized file names. The file names are very difficult to guess (for example: id84hBDs4g0a73nb0Ms9.png) and I would only want users who know the file name to access them. This means that the Amazon S3 bucket is technically public, but I have to restrict users from "scanning" / "listing" the folder. The user should only be able to access the files they know the file name to and not other files. Is this a possible setting in Amazon S3?
You are wanting to implement Security through obscurity - Wikipedia. Please note that it is not a form of complete security, as anyone who knows the names of the objects can access them.
You can simply add a Bucket Policy that makes all objects in the bucket (or a path within the bucket) 'public'. This policy allows access to the objects, but not listing of the bucket.
From Bucket policy examples - Amazon Simple Storage Service:
{
"Version":"2012-10-17",
"Statement":[
{
"Effect":"Allow",
"Principal": "*",
"Action": "s3:GetObject",
"Resource": "arn:aws:s3:::YOUR-BUCKET/*"
}
]
}
You will first need to disable Block Public Access on the bucket to be able to store this bucket policy.
I have a S3 bucket on AWS to which I am uploading images from the frontend.
After successfully uploading an image to S3, this is the URL I get -
https://cewa-foundation-2020.s3.amazonaws.com/image8_%281%29.webp-1628768330444.webp
I want to make this URL public so that anyone with this link can view the image.
How can I achieve this?
To make every object public you should add a Bucket Policy to the bucket.
Go to the bucket's Permissions tab
Go to the Block public access options
Turn off the two options that mention Bucket Policies:
Below that, add a Bucket Policy that grants access to anonymous users:
{
"Version":"2012-10-17",
"Statement":[
{
"Sid": "PublicRead",
"Effect": "Allow",
"Principal": "*",
"Action": "s3:GetObject",
"Resource": "arn:aws:s3:::YOUR-BUCKET-NAME/*"
}
]
}
All objects in the bucket can now be accessed by anyone on the Internet. However, they will not be able to list the contents of the bucket, so they will need to know the exact name of the object they want to access.
You can make an object public by doing these below steps:
Open the object by choosing the link on the object name.
Choose the Permissions tab.
Choose Edit.
In the Everyone section, select Objects Read.
Select I understand the effects of these changes on this object.
Choose Save changes.
This is just one of the ways of doing it. Check the below link for more such ways.
Source: https://aws.amazon.com/premiumsupport/knowledge-center/read-access-objects-s3-bucket/
My web app allows different user to upload different files. Currently putting them all in one bucket, something like:
A12345-Something.zip
B67890-Lorem.zip
A12345-... is file uploaded by user id A12345.
B67890-... is file uploaded by user id B67890.
This is my S3 bucket policy:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "PublicRead",
"Effect": "Allow",
"Principal": "*",
"Action": "s3:GetObject",
"Resource": "arn:aws:s3:::xxxx/*"
}
]
}
So far, this is all good, user A12345 can download the zip file by accessing https://xxxx.s3.ap-south-1.amazonaws.com/A12345-Something.zip
But the AWS interface gives me a warning that this bucket is a public bucket and it is highly recommended to not set it to public.
I am not sure but it is indeed very wrong if the policy above allows someone to list all objects from all users in my bucket and then access them one by one.
I think I need a policy that only allows reading a specific object if the full path is provided (assuming only that user will have access to that full path), but disallow listing of objects?
How should the policy looks like?
The policy you've specified allows someone to get all objects which means if they have the path they can retrieve that file publicly in the browser.
The permission ListObjects would be the permission that allows people to list all of the objects in your S3 bucket, this is not included.
If only specific users should be accessing this content, you should take a look at using signed URLs instead, this would prevent someone guessing or somehow gaining access to a link you do not want them to have.
This warning is in place to protect sensitive data being left exposed to the world, which is recent times has caused large volumes of private company data to be leaked.
I have a static website hosted on an aws s3 bucket. I am using a few different api's like google, trello etc. I am not sure how to keep some of these keys private as I set up my bucket to use PublicReadForGetBucketObjects which makes the entire website public. I have looked into AssumeRoleWithWebIdentity and permissions to restrict access but still cannot figure out how to make one of my files private. It seems to me that this is probably something easy but I cannot find a way.
Here is what my bucket policy looks like
{
"Version": "2008-10-17",
"Statement": [
{
"Sid": "PublicReadForGetBucketObjects",
"Effect": "Allow",
"Principal": {
"AWS": "*"
},
"Action": "s3:GetObject",
"Resource": "arn:aws:s3:::[my bucket]/*"
}
]
}
Thanks
The policy you have listed can apply permissions based on path. For example, setting the Resource to arn:aws:s3:::[my bucket]/public/* would only make the public sub-directory public (or more accurately, any path that starts with /public/).
Similarly, a policy can also define a path to specifically Deny, which will override the Allow (so you could make everything public but then specifically deny certain files and paths)
However, you mention that you would like to keep some files private, yet this is a static website, with no compute component. It would not be possible for only 'some' of your website to access the desired objects, since all the logic is taking place in your users' browsers rather than on your web server. Therefore, a file would either be public or private, but the private files could not be accessed as part of the static website. This might not be what you are trying to achieve.