A guide on Aws Security Token Service

A service provided by AWS to enhance the Security Measures for your resources (STS - Security Token Service )

1. Security Token Service (AWS STS)
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~ KaushikMohanraj

2. Blazeclan
Agenda
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•What is STS and what it has to offer…
•Recap on AWS IAM as prerequisite
•Why STS ????
•Brief information on its Details
•Use cases

3. Blazeclan
What is STS ??
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•AWS STS : Security Token Service
•The AWS Security Token Service is a web service that enables you to request
temporary, limited-privilege credentials for AWS Identity and Access Management
(IAM) users or for users that you authenticate (federated users).

4. Blazeclan
And what was IAM …???
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•AWS Identity and Access Management (IAM) enables you to securely control
accessto AWS services and resources for your users.
•IAM enables you to create and manage users in AWS and access AWS
resources.
•IAM offers greater security, flexibility, and control when using AWS.
•IAM enables you to:
Manage IAM users and their access
Manage access for federated users

5. Blazeclan
A brush up on IAM Role, IAM User and IAM Group is…
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•IAM User:
A user is an individual, system, or application that interacts with AWS
programmatically
•IAM Group:
A group is a collection of users. Groups don't directly interact with AWS; only
users do
•IAM Role:
A role is an entity that has a set of permissions, and that another entity assumes
to make calls to access your AWS resources.
GET http://169.254.169.254/latest/meta-data/iam/security-credentials/[role]

6. Blazeclan
Why STS…
When requested for Access through an STS API call it would typically return
Temporary Security credentials consisting of :
•Security Token
•An Access Key ID
•A Secret Access Key
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•The access Key ID & Secret Access Key generated with the token cannot be used
without the token.
•There are No limits on the number of “Sets” that we can create.
•STS service is designed to have limited access on a couple of Services.(Link)

7. Blazeclan
Ways to Access STS
•API Calls
•AWS offers SDK’s for selected languages, namely
•Java
•PHP
•.Net
•Ruby
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Link for any further
reference

8. Blazeclan
Types of User for whom you would Enable Access..
•Enable Access for IAM Users
•Enable Access for Federated Users
•Delegating API Access to Services
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9. Blazeclan
Creating Temporary Security Credentials to Enable Access for
IAM Users
•IAM users can use the AWS Security Token Service
GetSessionTokenAPI action to create temporary security
credentials for themselves
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Example Request:
https://sts.amazonaws.com/
?Version=2011-06-15
&Action=GetSessionToken
&DurationSeconds=3600
&AUTHPARAMS
Action
Validity

10. Blazeclan
GetSessionTokenRequest Description
•Request Parameters
•DurationSeconds
•SerialNumber
•The identification number of the MFA device for
the user.
•TokenCode
•The value provided by the MFA device.
(Non of them are mandatory)
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Note: You can specify the duration of the temporary security credentials to be from 15
minutesto 36 hours. By default, the credentials are valid for 12 hours.
Linkfor further Details

11. Blazeclan
Continued….
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Expiration Time
Secret Access Key
Access Key ID

12. Blazeclan
You Still think you account would be compromised ??
Temporary Security Credentials for IAM Users with Multi-Factor
Authentication (MFA)
•The following is an example of aGetSessionTokenrequest with an MFA verification
code and device serial number using the STS Query API.
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13. Blazeclan
Creating Temporary Security Credentials to Enable Access for
Federated Users
So who is a Federated User ?
A Non-AWS user whose identity can be authenticated.
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Creating Temporary Security Credentials to Enable Access for
Federated Users
Grant temporary access to a non-AWS user whose identity you
can authenticate (a federated user) use the AWS
STSGetFederationTokenaction
Action
Validity
Authentication From the Identity Broker

15. Blazeclan
GetFederationTokenRequest Description
•Request Parameters
•DurationSeconds–
(Optional)
•Name –(Mandatory)
•Policy –(Optional)
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Note: You can specify the duration of the temporary security credentials to be from 15 minutesto 36
hours. By default, the credentials are valid for 12 hours only if created by IAM USERs; credentials
created using account credentials have a maximum duration of one hour.
Linkfor further Details

16. Blazeclan
Continued…..
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Expiration Time
Secret Access Key
Access Key ID
Federated User ID

17. Blazeclan
GetFederationTokenResponse Description
•Response Parameters
•Credentials
•FederatedUser
•Identifiers for the federated user associated with the
credentials. You can use the federated user's ARN in your
resource policies.
•PackedPolicySize
•A percentage value indicating the size of the policy in packed
form. Policies for which the packed size is greater than 100%
of the allowed value are rejected by the service.
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18. Blazeclan
Creating Temporary Security Credentials for Delegating API
Access
•We Know that we can delegate access to our AWS resources by
using IAM roles.
•IAM roles allow you to establish trusted relationships with other
AWS accounts (trusted entities)
•IAM users from trusted entities can use the AWS Security Token
ServiceAssumeRoleaction to obtain temporary security
credentials
•With the temporary security credentials, callers are granted the
permissions that are defined in the role.(only)
Note: You can specify the duration of the temporary security credentials to be from 15
minutesto one hour. By default, the credentials are valid for one hour.
Linkfor further Details
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19. Blazeclan
Continued…
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Requirements for assuming a role
To assume a role, the caller must meet the following
requirements:
•The caller must have permission to callAssumeRolefor the
specific role.
•The role defines the caller's AWS account ID as a trusted entity.
•The caller must use IAM user credentials to assume a role.
•If the role has an external ID defined, the caller must pass that
external ID when calling AssumeRole

20. Blazeclan
External ID (Use-case Specific)
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•Anexternal IDis an additional piece of information that you can
specify when assuming an IAM role.
•As a third party, you might have multiple customers who use your
service to access or manage their AWS resources. You assign an
external ID that is associated with each customer. Customers
include this ID when they create a role that you can assume.
•Then each time you assume a role, you include the external ID as
part of the request.
•The external ID can be any identifier that is used to identify each
customer (it doesn't have to be a secret value). The only
requirement is that the external ID must be unique for each
customer.

21. Blazeclan
AssumeRoleRequest Description
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Action
Validity
External ID

22. Blazeclan
AssumeRoleRequest Description
Request Parameters
•DurationSeconds–(Optional)
•ExternalId–(Optional)
•Policy –(Optional)
•RoleArn–(Mandatory)
•The ARN of the role that the caller is assuming.
•RoleSessionName–(Mandatory)
•An identifier for the assumed role session. The session name is
included as part of the AssumedRoleUser
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23. Blazeclan
AssumeRoleResponse Description
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Expiration Time
Packed Policy Size
Assumed Role
ARN

24. Blazeclan
AssumeRoleResponse Description
•Response Parameters
•AssumedRoleUser
•Credentials
•PackedPolicySize
•A percentage value indicating the size of the policy in packed
form. Policies for which the packed size is greater than 100%
of the allowed value are rejected by the service.
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25. Blazeclan
How Permissions Work ?
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Source : http://docs.aws.amazon.com/STS/latest/UsingSTS/FederationPermissions.html

26. Blazeclan
Use Cases
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Source: http://docs.aws.amazon.com/STS/latest/UsingSTS/STSUseCases.html

27. Blazeclan
Use Cases
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Source: http://docs.aws.amazon.com/STS/latest/UsingSTS/STSUseCases.html

28. Blazeclan
Cross Account Delegation(ClouldlyticsScenario)
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Source : http://docs.aws.amazon.com/IAM/latest/UserGuide/Delegation.html

29. Blazeclan
Content References and Suggested Pages:
AWS Documentation -Using Temporary Security Credentials
AWS Documentation -AWS Security Token Service
AWS Documentation -Using Temporary Security Credentials
AWS Documentation -AWS Identity and Access Management
AWS Documentation -Using Temporary Security Credentials
AWS Documentation -AWS Identity and Access Management
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30. Thank you
Thank You