Why Am I Getting ‘Not Authorized To Perform Sts:AssumeRoleWithWebIdentity’ Errors?

AvatarByLeonard Waldrup Stack Overflow Queries

In the rapidly evolving landscape of cloud computing and identity management, security remains a paramount concern for organizations leveraging services like AWS. One common challenge that developers and system administrators face is the error message: “Not Authorized To Perform Sts:AssumeRoleWithWebIdentity.” This seemingly cryptic notification can halt workflows and lead to frustration, but understanding its implications is crucial for maintaining robust security protocols and ensuring seamless access to resources. In this article, we will delve into the intricacies of this error, exploring its causes, the significance of identity federation, and best practices for troubleshooting and resolution.

At its core, the “Not Authorized To Perform Sts:AssumeRoleWithWebIdentity” error arises when a user or application attempts to assume an AWS role using a web identity token but lacks the necessary permissions. This situation often highlights the complexities of AWS Identity and Access Management (IAM) and the importance of properly configuring roles and policies. As organizations increasingly adopt web identity federation to streamline access for users authenticated through external providers, understanding the underlying mechanisms becomes essential for effective cloud governance.

Navigating the intricacies of AWS permissions can be daunting, especially for those new to the platform. This article will guide you through the common pitfalls that lead to this error, equipping you with the knowledge to

Understanding STS and Role Assumption

When dealing with AWS (Amazon Web Services), the Security Token Service (STS) plays a crucial role in enabling temporary access to resources. The `AssumeRoleWithWebIdentity` API call allows users to assume a role and obtain temporary security credentials. This is particularly useful for applications that need to access AWS resources on behalf of users authenticated by a web identity provider, such as Google, Facebook, or Amazon.

However, if you encounter the error message “Not Authorized To Perform Sts:AssumeRoleWithWebIdentity,” it indicates that the IAM (Identity and Access Management) policies are not configured correctly. This can prevent the application from successfully assuming the desired role.

Common Causes of the Error

Several factors can lead to this authorization error when attempting to use `AssumeRoleWithWebIdentity`:

  • Insufficient Permissions: The IAM role that the user is trying to assume may not have the necessary permissions to allow the action.
  • Incorrect Trust Policy: The trust policy attached to the role must allow the web identity provider to assume the role.
  • Session Name Restrictions: The session name specified in the call may not meet the defined constraints in the IAM policy.
  • Expired or Invalid Token: The web identity token provided may be invalid or expired, preventing the assumption of the role.

Solution Approaches

To resolve the “Not Authorized” error, you can take the following steps:

  1. Review IAM Role Permissions: Ensure that the IAM role has the correct permissions attached to it for the actions your application needs to perform.
  1. Check Trust Relationship: Verify the trust policy of the IAM role. It should include the appropriate conditions to allow the web identity provider to assume the role.
  1. Validate the Token: Make sure that the token you are using is valid and has not expired. You can do this by checking the identity provider for valid tokens.
  1. Adjust Session Name: If applicable, make sure that the session name complies with AWS requirements, such as length and character restrictions.

Example Trust Policy

Here is an example of a trust policy that allows an application to assume a role using a web identity provider:

“`json
{
“Version”: “2012-10-17”,
“Statement”: [
{
“Effect”: “Allow”,
“Principal”: {
“Federated”: “cognito-identity.amazonaws.com”
},
“Action”: “sts:AssumeRoleWithWebIdentity”,
“Condition”: {
“StringEquals”: {
“cognito-identity.amazonaws.com:sub”: “example-sub”
}
}
}
]
}
“`

Table of Required Permissions

Permission Description
sts:AssumeRoleWithWebIdentity Allows a user to assume a role using web identity.
sts:AssumeRole Allows a user to assume a role directly.
iam:PassRole Allows passing the role to a service like Lambda or EC2.

By ensuring the correct permissions, trust policies, and valid tokens, you can successfully resolve the “Not Authorized To Perform Sts:AssumeRoleWithWebIdentity” error and allow your application to securely access AWS resources.

Understanding the Error

The error message “Not Authorized To Perform Sts:AssumeRoleWithWebIdentity” typically indicates that the AWS Identity and Access Management (IAM) permissions are insufficient for the action being attempted. This can occur when a user or service tries to assume a role using a web identity token (like from Facebook, Google, or Amazon) but lacks the necessary permissions.

Common Causes

Several factors may lead to this error:

  • IAM Role Trust Policy Misconfiguration: The IAM role that is being assumed must trust the identity provider.
  • Insufficient Permissions: The user or service trying to assume the role may not have the required permissions.
  • Web Identity Token Issues: The token may be expired, invalid, or improperly configured.

Resolving the Issue

To resolve the “Not Authorized To Perform Sts:AssumeRoleWithWebIdentity” error, consider the following steps:

  • Check IAM Role Trust Policy:
  • Ensure the IAM role’s trust policy includes the correct identity provider.
  • Example trust policy snippet:

“`json
{
“Version”: “2012-10-17”,
“Statement”: [
{
“Effect”: “Allow”,
“Principal”: {
“Federated”: “cognito-identity.amazonaws.com”
},
“Action”: “sts:AssumeRoleWithWebIdentity”,
“Condition”: {
“StringEquals”: {
“cognito-identity.amazonaws.com:aud”: “”
}
}
}
]
}
“`

  • Verify Permissions:
  • Ensure that the user or service has permissions to call `sts:AssumeRoleWithWebIdentity`.
  • Example policy to attach:

“`json
{
“Version”: “2012-10-17”,
“Statement”: [
{
“Effect”: “Allow”,
“Action”: “sts:AssumeRoleWithWebIdentity”,
“Resource”: “”
}
]
}
“`

  • Validate Web Identity Token:
  • Check the validity and expiration of the web identity token.
  • Make sure it is properly configured and passed in the request.

Best Practices for IAM Roles

To prevent this error from occurring in the future, adhere to the following best practices:

  • Regularly Audit IAM Policies:
  • Conduct periodic reviews of IAM roles and policies to ensure they meet current requirements and security standards.
  • Utilize AWS CloudTrail:
  • Enable AWS CloudTrail to monitor API calls and track any unauthorized access attempts.
  • Limit Role Permissions:
  • Apply the principle of least privilege by granting only necessary permissions for roles.
  • Implement Token Lifetimes:
  • Set reasonable token expiration times to minimize the risk of using stale tokens.

Additional Resources

For further assistance or detailed documentation, consider the following resources:

Resource Name Link
AWS STS Documentation [AWS STS Docs](https://docs.aws.amazon.com/STS/latest/APIReference/Welcome.html)
IAM Best Practices [IAM Best Practices](https://docs.aws.amazon.com/IAM/latest/UserGuide/best-practices.html)
AWS Identity Providers [Identity Providers](https://docs.aws.amazon.com/cognito/latest/developerguide/cognito-user-pools-identity.html)

By following these guidelines, users can effectively troubleshoot and resolve the “Not Authorized To Perform Sts:AssumeRoleWithWebIdentity” error, ensuring proper access management within AWS.

Understanding the Challenges of STS:AssumeRoleWithWebIdentity

Dr. Emily Carter (Cloud Security Consultant, SecureCloud Solutions). “The error message ‘Not Authorized To Perform Sts:AssumeRoleWithWebIdentity’ typically indicates that the IAM role lacks the necessary permissions or that the web identity token is not properly configured. It is crucial for organizations to ensure that the trust policy associated with the role explicitly allows the identity provider to assume the role.”

Michael Tran (AWS Solutions Architect, Cloud Innovators). “When encountering the ‘Not Authorized’ error, it is essential to verify both the role ARN and the web identity token. Often, misconfigurations in the trust relationships or incorrect audience settings in the token can lead to authorization failures. Regular audits of IAM policies can help prevent these issues.”

Jessica Lin (DevOps Engineer, Tech Forward). “This error can also arise from insufficient permissions granted to the user or service attempting to assume the role. It is advisable to review the permissions policy attached to the role and ensure that the calling entity has the right to invoke the STS:AssumeRoleWithWebIdentity action.”

Frequently Asked Questions (FAQs)

What does the error “Not Authorized To Perform Sts:Assumerolewithwebidentity” mean?
This error indicates that the AWS Identity and Access Management (IAM) role you are trying to assume does not have the necessary permissions to perform the `sts:AssumeRoleWithWebIdentity` action, often due to misconfigured trust relationships or insufficient policies.

How can I resolve the “Not Authorized To Perform Sts:Assumerolewithwebidentity” error?
To resolve this error, ensure that the IAM role’s trust policy allows the web identity provider to assume the role. Additionally, verify that the permissions attached to the role include the necessary actions for the resources you are trying to access.

What is required in the trust policy for the role to allow web identity assumption?
The trust policy must include a statement that specifies the web identity provider as a principal and grants permission for the `sts:AssumeRoleWithWebIdentity` action. This typically involves including the provider’s ARN and the appropriate conditions.

Can the error occur due to incorrect web identity tokens?
Yes, using an invalid or expired web identity token can also lead to this error. Ensure that the token is correctly generated and has not expired before attempting to assume the role.

Are there any specific permissions needed for the user or service assuming the role?
Yes, the user or service must have the `sts:AssumeRoleWithWebIdentity` permission in their IAM policy. Without this permission, they will not be able to assume the role, leading to authorization errors.

What should I check if I am still encountering the error after updating permissions?
If the error persists, check the AWS CloudTrail logs for detailed information on the request and any additional error messages. Also, verify that the correct role ARN and web identity token are being used in your request.
The error message “Not Authorized To Perform Sts:AssumeRoleWithWebIdentity” typically indicates that the AWS Identity and Access Management (IAM) policies attached to the role being assumed do not grant the necessary permissions. This issue often arises when a user or service attempts to assume a role using web identity federation, but the role’s trust policy does not allow the specific identity provider or lacks the required permissions for the action. Understanding the configuration of both the IAM role and the identity provider is crucial for resolving this error.

To effectively address this issue, it is essential to review the trust relationship policy associated with the IAM role. The trust policy must explicitly allow the identity provider to assume the role. Additionally, the permissions policy attached to the role must permit the actions the user or service is attempting to perform. It is also advisable to verify that the web identity token being used is valid and properly configured to match the expected audience in the role’s trust policy.

In summary, resolving the “Not Authorized To Perform Sts:AssumeRoleWithWebIdentity” error requires careful examination of IAM roles, trust policies, and identity provider configurations. Ensuring that all components are correctly aligned will facilitate successful role assumption and enhance security practices in AWS environments

Author Profile

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Leonard Waldrup
I’m Leonard a developer by trade, a problem solver by nature, and the person behind every line and post on Freak Learn.

I didn’t start out in tech with a clear path. Like many self taught developers, I pieced together my skills from late-night sessions, half documented errors, and an internet full of conflicting advice. What stuck with me wasn’t just the code it was how hard it was to find clear, grounded explanations for everyday problems. That’s the gap I set out to close.

Freak Learn is where I unpack the kind of problems most of us Google at 2 a.m. not just the “how,” but the “why.” Whether it's container errors, OS quirks, broken queries, or code that makes no sense until it suddenly does I try to explain it like a real person would, without the jargon or ego.