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A number of unbiased software program distributors (ISVs) and software program as a service (SaaS) suppliers must entry their prospects’ Amazon Net Companies (AWS) accounts, particularly if the SaaS product accesses information from buyer environments. SaaS suppliers have adopted a number of variations of this third-party entry state of affairs. In some circumstances, the suppliers ask the shopper for an entry key and a secret key, which isn’t really useful as a result of these are long-term consumer credentials and require processes to be constructed for periodic rotation. Nevertheless, normally, the supplier has an integration information with particular particulars on making a cross-account AWS Id and Entry Administration (IAM) position.
In all these eventualities, as a SaaS vendor, you must add the mandatory protections to your SaaS implementation. At AWS, safety is the highest precedence and we advocate that prospects observe greatest practices and incorporate safety of their product design. On this weblog submit meant for SaaS suppliers, I describe 3 ways to enhance your cross-account entry implementation in your merchandise.
Why is that this necessary?
As a safety specialist, I’ve labored with a number of ISV prospects on enhancing the safety of their merchandise, particularly on this third-party cross-account entry state of affairs. Shoppers of your SaaS merchandise don’t need to give extra entry permissions than are mandatory for the product’s correct functioning. On the similar time, you must preserve and supply a safe SaaS product to guard your prospects’ and your personal AWS accounts from unauthorized entry or privilege escalations.
Let’s think about a hypothetical state of affairs with a easy SaaS implementation the place a buyer is planning to make use of a SaaS product. In Determine 1, you possibly can see that the SaaS product has a number of totally different elements performing separate features, for instance, a SaaS product with separate elements performing compute evaluation, storage evaluation, and log evaluation. The SaaS supplier asks the shopper to offer IAM consumer credentials and makes use of these of their product to entry buyer sources. Let’s take a look at three methods for enhancing the cross-account entry for this state of affairs. Every approach builds on the earlier one, so you might undertake an incremental method to implement these methods.
![Figure 1: SaaS architecture using customer IAM user credentials](https://d2908q01vomqb2.cloudfront.net/22d200f8670dbdb3e253a90eee5098477c95c23d/2023/11/14/img1-5.png)
Determine 1: SaaS structure utilizing buyer IAM consumer credentials
Method 1 – Utilizing IAM roles and an exterior ID
As said beforehand, IAM consumer credentials are long-term, so prospects would want to implement processes to rotate these periodically and share them with the ISV.
As a greater choice, SaaS product elements can use IAM roles, which give short-term credentials to the part assuming the position. These credentials must be refreshed relying on the position’s session length setting (the default is 1 hour) to proceed accessing the sources. IAM roles additionally present a bonus for auditing functions as a result of every time an IAM principal assumes a task, a brand new session is created, and this can be utilized to establish and audit exercise for separate classes.
When utilizing IAM roles for third-party entry, an necessary consideration is the confused deputy drawback, the place an unauthorized entity might coerce the product elements into performing an motion in opposition to one other prospects’ sources. To mitigate this drawback, a extremely really useful method is to make use of the exterior ID parameter when assuming roles in prospects’ accounts. It’s necessary and really useful that you just generate these exterior ID parameters to verify they’re distinctive for every of your prospects, for instance, utilizing a buyer ID or related attribute. For exterior ID character restrictions, see the IAM quotas web page. Your prospects will use this exterior ID of their IAM position’s belief coverage, and your product elements will move this as a parameter in all AssumeRole API calls to buyer environments. An instance of the belief coverage principal and situation blocks for the position to be assumed within the buyer’s account follows:
![Figure 2: SaaS architecture using an IAM role and external ID](https://d2908q01vomqb2.cloudfront.net/22d200f8670dbdb3e253a90eee5098477c95c23d/2023/11/14/img2-4.png)
Determine 2: SaaS structure utilizing an IAM position and exterior ID
Method 2 – Utilizing least-privilege IAM insurance policies and position chaining
As an IAM greatest observe, we advocate that an IAM position ought to solely have the minimal set of permissions as required to carry out its features. When your prospects create an IAM position in Method 1, they may inadvertently present extra permissions than mandatory to make use of your product. The position might have permissions related to a number of AWS companies and may change into overly permissive. Should you present granular permissions for separate AWS companies, you may attain the coverage measurement quota or insurance policies per position quota. See IAM quotas for extra data. That’s why, along with Method 1, we advocate that every part have a separate IAM position within the buyer’s account with solely the minimal permissions required for its features.
As part of your integration information to the shopper, you must ask them to create acceptable IAM insurance policies for these IAM roles. There must be a transparent separation of duties and least privilege entry for the product elements. For instance, an account-monitoring SaaS supplier may use a separate IAM position for Amazon Elastic Compute Cloud (Amazon EC2) monitoring and one other one for AWS CloudTrail monitoring. Your elements may also use separate IAM roles in your personal AWS account. Nevertheless, you may need to present a single integration IAM position to prospects to determine the belief relationship with every part position of their account. In impact, you’ll be utilizing the idea of position chaining to entry your buyer’s accounts. The auditing mechanisms on the shopper’s finish will solely show the combination IAM position classes.
When utilizing position chaining, it’s essential to pay attention to sure caveats and limitations. Your elements will every have separate roles: Position A, which can assume the combination position (Position B), after which use the Position B credentials to imagine the shopper position (Position C) in buyer’s accounts. It is advisable correctly outline the proper permissions for every of those roles, as a result of the permissions of the earlier position aren’t handed whereas assuming the position. Optionally, you possibly can move an IAM coverage doc often known as a session coverage as a parameter whereas assuming the position, and the efficient permissions will likely be a logical intersection of the handed coverage and the hooked up permissions for the position. To be taught extra about these session insurance policies, see session insurance policies.
One other consideration of utilizing position chaining is that it limits your AWS Command Line Interface (AWS CLI) or AWS API position session length to a most of 1 hour. Because of this it’s essential to monitor the classes and carry out credential refresh actions each hour to proceed accessing the sources.
![Figure 3: SaaS architecture with role chaining](https://d2908q01vomqb2.cloudfront.net/22d200f8670dbdb3e253a90eee5098477c95c23d/2023/11/14/img3-3.png)
Determine 3: SaaS structure with position chaining
Method 3 – Utilizing position tags and session tags for attribute-based entry management
While you create your IAM roles for position chaining, you outline which entity can assume the position. You have to so as to add every component-specific IAM position to the combination position’s belief relationship. Because the variety of elements inside your product will increase, you may attain the utmost size of the position belief coverage. See IAM quotas for extra data.
That’s why, along with the above two methods, we advocate utilizing attribute-based entry management (ABAC), which is an authorization technique that defines permissions primarily based on tag attributes. You need to tag all of the part IAM roles with position tags and use these position tags as situations within the belief coverage for the combination position as proven within the following instance. Optionally, you might additionally embody directions within the product integration information for tagging prospects’ IAM roles with sure position tags and modify the IAM coverage of the combination position to permit it to imagine solely roles with these position tags. This helps in lowering IAM coverage size and minimizing the chance of reaching the IAM quota.
One other consideration for enhancing the auditing and traceability in your product is IAM position session tags. These could possibly be useful for those who use CloudTrail log occasions for alerting on particular position classes. In case your SaaS product additionally operates on CloudTrail logs, you might use these session tags to establish the totally different classes out of your product. Versus position tags, that are tags hooked up to an IAM position, session tags are key-value pair attributes that you just move if you assume an IAM position. These can be utilized to establish a session and additional management or limit entry to sources primarily based on the tags. Session tags may also be used together with position chaining. While you use session tags with position chaining, you possibly can set the keys as transitive to just be sure you move them to subsequent classes. CloudTrail log occasions for these position classes will include the session tags, transitive tags, and position (additionally known as principal) tags.
Conclusion
On this submit, we mentioned three incremental methods that construct on one another and are necessary for SaaS suppliers to enhance safety and entry management whereas implementing cross-account entry to their prospects. As a SaaS supplier, it’s necessary to confirm that your product adheres to safety greatest practices. While you enhance safety in your product, you’re additionally enhancing safety in your prospects.
To see extra tutorials about cross-account entry ideas, go to the AWS documentation on IAM Roles, ABAC, and session tags.
In case you have suggestions about this submit, submit feedback within the Feedback part under. In case you have questions on this submit, begin a brand new thread on the AWS Id and Entry Administration re:Put up or contact AWS Assist.
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