For cross-account access from EC2 in Account A to a Kinesis data stream in Account B, the recommended secure pattern is to use STS AssumeRole into a role in the resource-owning account (Account B). This ensures Account B retains control over what permissions are granted to external principals and allows Account A workloads to obtain temporary credentials scoped to the required actions.
First, create an IAM role in Account B that has the necessary Kinesis read permissions (such as kinesis:GetRecords, kinesis:GetShardIterator, kinesis:DescribeStream, and related read actions as required). That corresponds to option B. This role represents the permission boundary controlled by Account B for accessing its stream.
Second, configure the role’s trust policy in Account B to allow the instance profile role (or another IAM principal) from Account A to assume it. In practice, the trust relationship is defined on the Account B role and specifies the Account A role as the trusted principal, enabling sts:AssumeRole. This corresponds to option C (the intent is “allow the instance profile role to assume the IAM role in Account B”).
Option A alone is insufficient because permissions in Account A do not grant access to resources owned by Account B without an explicit cross-account authorization path. Option D is incorrect because trust policies do not “allow reads from the stream”; they allow principals to assume roles, and permissions policies allow service actions. Option E (resource-based policy) is not the primary mechanism for Kinesis Data Streams cross-account access in this scenario compared with the standard role assumption model; the secure and common approach is to assume a role in the owning account.
Therefore, the correct actions are B (create the role with read permissions in Account B) and C (configure trust to allow Account A’s instance role to assume it).
