AWS AWSEC2 high security documentation change
Summary
Rewrote documentation to focus on migration tools and recommended transition path to IMDSv2, removing technical implementation details of IMDSv1/v2. Added sections about IMDS Packet Analyzer, CloudWatch metrics, IAM policies, and step-by-step transition guidance.
Security assessment
The changes promote mandatory use of IMDSv2, which was introduced to mitigate SSRF vulnerabilities. References to security tools (IMDS Packet Analyzer), metrics tracking v1 usage, and IAM policy enforcement all relate to strengthening security posture by phasing out the less secure IMDSv1 protocol.
Diff
diff --git a/AWSEC2/latest/UserGuide/instance-metadata-transition-to-version-2.md index b4af12213..777312476 100644 --- a/AWSEC2/latest/UserGuide/instance-metadata-transition-to-version-2.md +++ b/AWSEC2/latest/UserGuide/instance-metadata-transition-to-version-2.md @@ -1 +1 @@ -[](/pdfs/AWSEC2/latest/UserGuide/ec2-ug.pdf#configuring-instance-metadata-service "Open PDF") +[](/pdfs/AWSEC2/latest/UserGuide/ec2-ug.pdf#instance-metadata-transition-to-version-2 "Open PDF") @@ -5 +5 @@ -How IMDSv2 worksSupported SDKsExamples for IMDSv2Examples for IMDSv1 +Tools for helping with the transition to IMDSv2Recommended path to requiring IMDSv2 @@ -7 +7 @@ How IMDSv2 worksSupported SDKsExamples for IMDSv2Examples for IMDSv1 -# Use the Instance Metadata Service to access instance metadata +# Transition to using Instance Metadata Service Version 2 @@ -9,20 +9 @@ How IMDSv2 worksSupported SDKsExamples for IMDSv2Examples for IMDSv1 -You can access instance metadata from a running instance using one of the following methods: - - * Instance Metadata Service Version 2 (IMDSv2) – a session-oriented method - -For examples, see Examples for IMDSv2. - - * Instance Metadata Service Version 1 (IMDSv1) – a request/response method - -For examples, see Examples for IMDSv1. - - - - -By default, you can use either IMDSv1 or IMDSv2, or both. - -You can configure the Instance Metadata Service (IMDS) on each instance so that local code or users must use IMDSv2. When you specify that IMDSv2 must be used, IMDSv1 no longer works. For information about how to configure your instance to use IMDSv2, see [Configure the Instance Metadata Service options](./configuring-instance-metadata-options.html). - -The `PUT` or `GET` headers are unique to IMDSv2. If these headers are present in the request, then the request is intended for IMDSv2. If no headers are present, it is assumed the request is intended for IMDSv1. - -For an extensive review of IMDSv2, see [Add defense in depth against open firewalls, reverse proxies, and SSRF vulnerabilities with enhancements to the EC2 Instance Metadata Service](https://aws.amazon.com/blogs/security/defense-in-depth-open-firewalls-reverse-proxies-ssrf-vulnerabilities-ec2-instance-metadata-service/). +If you want to migrate your instances so that local code or users must use Instance Metadata Service Version 2 (IMDSv2), we recommend that you use the following tools and transition path. @@ -32,479 +13 @@ For an extensive review of IMDSv2, see [Add defense in depth against open firewa - * How Instance Metadata Service Version 2 works - - * Use a supported AWS SDK - - * Examples for IMDSv2 - - * Examples for IMDSv1 - - - - -## How Instance Metadata Service Version 2 works - -IMDSv2 uses session-oriented requests. With session-oriented requests, you create a session token that defines the session duration, which can be a minimum of one second and a maximum of six hours. During the specified duration, you can use the same session token for subsequent requests. After the specified duration expires, you must create a new session token to use for future requests. - -###### Note - -The examples in this section use the IPv4 address of the Instance Metadata Service (IMDS): `169.254.169.254`. If you are retrieving instance metadata for EC2 instances over the IPv6 address, ensure that you enable and use the IPv6 address instead: `[fd00:ec2::254]`. The IPv6 address of the IMDS is compatible with IMDSv2 commands. The IPv6 address is only accessible on [Nitro-based instances](./instance-types.html#instance-hypervisor-type) in an [IPv6-supported subnet](https://docs.aws.amazon.com/vpc/latest/userguide/configure-subnets.html#subnet-ip-address-range) (dual stack or IPv6 only). - -The following examples use a shell script and IMDSv2 to retrieve the top-level instance metadata items. Each example: - - * Creates a session token lasting six hours (21,600 seconds) using the `PUT` request - - * Stores the session token header in a variable named `TOKEN` (Linux instances) or `token` (Windows instances) - - * Requests the top-level metadata items using the token - - - - -You can run two separate commands, or combine them. - -**Separate commands** - -First, generate a token using the following command. - - - [ec2-user ~]$ TOKEN=`curl -X PUT "http://169.254.169.254/latest/api/token" -H "X-aws-ec2-metadata-token-ttl-seconds: 21600"` - -Then, use the token to generate top-level metadata items using the following command. - - - [ec2-user ~]$ curl -H "X-aws-ec2-metadata-token: $TOKEN" http://169.254.169.254/latest/meta-data/ - -**Combined commands** - -You can store the token and combine the commands. The following example combines the above two commands and stores the session token header in a variable named TOKEN. - -###### Note - -If there is an error in creating the token, instead of a valid token, an error message is stored in the variable, and the command will not work. - - - [ec2-user ~]$ TOKEN=`curl -X PUT "http://169.254.169.254/latest/api/token" -H "X-aws-ec2-metadata-token-ttl-seconds: 21600"` \ - && curl -H "X-aws-ec2-metadata-token: $TOKEN" http://169.254.169.254/latest/meta-data/ - -After you've created a token, you can reuse it until it expires. In the following example command, which gets the ID of the AMI used to launch the instance, the token that is stored in `$TOKEN` in the previous example is reused. - - - [ec2-user ~]$ curl -H "X-aws-ec2-metadata-token: $TOKEN" http://169.254.169.254/latest/meta-data/ami-id - - - PS C:\> [string]$token = Invoke-RestMethod -Headers @{"X-aws-ec2-metadata-token-ttl-seconds" = "21600"} -Method PUT -Uri http://169.254.169.254/latest/api/token - - - PS C:\> Invoke-RestMethod -Headers @{"X-aws-ec2-metadata-token" = $token} -Method GET -Uri http://169.254.169.254/latest/meta-data/ - -After you've created a token, you can reuse it until it expires. In the following example command, which gets the ID of the AMI used to launch the instance, the token that is stored in `$token` in the previous example is reused. - - - PS C:\> Invoke-RestMethod -Headers @{"X-aws-ec2-metadata-token" = $token} ` - -Method GET -uri http://169.254.169.254/latest/meta-data/ami-id - -When you use IMDSv2 to request instance metadata, the request must include the following: - - 1. Use a `PUT` request to initiate a session to the instance metadata service. The `PUT` request returns a token that must be included in subsequent `GET` requests to the instance metadata service. The token is required to access metadata using IMDSv2. - - 2. Include the token in all `GET` requests to the IMDS. When token usage is set to `required`, requests without a valid token or with an expired token receive a `401 - Unauthorized` HTTP error code. - - * The token is an instance-specific key. The token is not valid on other EC2 instances and will be rejected if you attempt to use it outside of the instance on which it was generated. - - * The `PUT` request must include a header that specifies the time to live (TTL) for the token, in seconds, up to a maximum of six hours (21,600 seconds). The token represents a logical session. The TTL specifies the length of time that the token is valid and, therefore, the duration of the session. - - * After a token expires, to continue accessing instance metadata, you must create a new session using another `PUT`. - - * You can choose to reuse a token or create a new token with every request. For a small number of requests, it might be easier to generate and immediately use a token each time you need to access the IMDS. But for efficiency, you can specify a longer duration for the token and reuse it rather than having to write a `PUT` request every time you need to request instance metadata. There is no practical limit on the number of concurrent tokens, each representing its own session. IMDSv2 is, however, still constrained by normal IMDS connection and throttling limits. For more information, see [Query throttling](./instancedata-data-retrieval.html#instancedata-throttling). - - - - -HTTP `GET` and `HEAD` methods are allowed in IMDSv2 instance metadata requests. `PUT` requests are rejected if they contain an X-Forwarded-For header. - -By default, the response to `PUT` requests has a response hop limit (time to live) of `1` at the IP protocol level. If you need a bigger hop limit, you can adjust it by using the [modify-instance-metadata-options](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/ec2/modify-instance-metadata-options.html) AWS CLI command. For example, you might need a bigger hop limit for backward compatibility with container services running on the instance. For more information, see [Modify instance metadata options for existing instances](./configuring-IMDS-existing-instances.html). - -## Use a supported AWS SDK - -To use IMDSv2, your EC2 instances must use an AWS SDK version that supports using IMDSv2. The latest versions of all the AWS SDKs support using IMDSv2. - -###### Important - -We recommend that you to stay up to date with SDK releases to keep up with the latest features, security updates, and underlying dependencies. Continued use of an unsupported SDK version is not recommended and is done at your discretion. For more information, see the [AWS SDKs and Tools maintenance policy](https://docs.aws.amazon.com/sdkref/latest/guide/maint-policy.html) in the _AWS SDKs and Tools Reference Guide_. - -The following are the minimum versions that support using IMDSv2: - - * [AWS CLI](https://github.com/aws/aws-cli) – 1.16.289 - - * [AWS Tools for Windows PowerShell](https://github.com/aws/aws-tools-for-powershell) – 4.0.1.0 - - * [AWS SDK for .NET](https://github.com/aws/aws-sdk-net) – 3.3.634.1 - - * [AWS SDK for C++](https://github.com/aws/aws-sdk-cpp) – 1.7.229 - - * [AWS SDK for Go](https://github.com/aws/aws-sdk-go) – 1.25.38 - - * [AWS SDK for Go v2](https://github.com/aws/aws-sdk-go-v2) – 0.19.0 - - * [AWS SDK for Java](https://github.com/aws/aws-sdk-java) – 1.11.678 - - * [AWS SDK for Java 2.x](https://github.com/aws/aws-sdk-java-v2) – 2.10.21 - - * [AWS SDK for JavaScript in Node.js](https://github.com/aws/aws-sdk-js) – 2.722.0 - - * [AWS SDK for Kotlin](https://github.com/awslabs/aws-sdk-kotlin) – 1.1.4 - - * [AWS SDK for PHP](https://github.com/aws/aws-sdk-php) – 3.147.7 - - * [AWS SDK for Python (Botocore)](https://github.com/boto/botocore) – 1.13.25 - - * [AWS SDK for Python (Boto3)](https://github.com/boto/boto3) – 1.12.6 - - * [AWS SDK for Ruby](https://github.com/aws/aws-sdk-ruby) – 3.79.0 - - - - -## Examples for IMDSv2 - -Run the following examples on your Amazon EC2 instance to retrieve the instance metadata for IMDSv2. - -On Windows instances, you can use Windows PowerShell or you can install cURL or wget. If you install a third-party tool on a Windows instance, ensure that you read the accompanying documentation carefully, as the calls and the output might be different from what is described here. - -###### Examples - - * Get the available versions of the instance metadata - - * Get the top-level metadata items - - * Get the values for metadata items - - * Get the list of available public keys - - * Show the formats in which public key 0 is available - - * Get public key 0 (in the OpenSSH key format) - - * Get the subnet ID for an instance - - * Get the instance tags for an instance - - - - -### Get the available versions of the instance metadata -