IAM policy conditions are powerful elements that allow you to specify when a policy statement should take effect. They add granular control over AWS resource access by evaluating specific criteria before granting or denying permissions.
Conditions use a key-value structure with condition operators…IAM policy conditions are powerful elements that allow you to specify when a policy statement should take effect. They add granular control over AWS resource access by evaluating specific criteria before granting or denying permissions.
Conditions use a key-value structure with condition operators. The basic syntax includes three components: the condition operator (like StringEquals, NumericLessThan, or Bool), the condition key (such as aws:SourceIp or s3:prefix), and the value to compare against.
Common condition operators include:
- StringEquals/StringNotEquals: For exact string matching
- StringLike: Supports wildcards (* and ?)
- NumericEquals/NumericGreaterThan: For number comparisons
- DateEquals/DateLessThan: For time-based conditions
- Bool: For boolean values
- IpAddress/NotIpAddress: For IP range restrictions
Global condition keys are available across all AWS services:
- aws:SourceIp: Restricts access based on IP address
- aws:CurrentTime: Enables time-based access control
- aws:SecureTransport: Requires HTTPS connections
- aws:PrincipalTag: Checks tags on the requesting principal
- aws:RequestedRegion: Limits actions to specific AWS regions
Service-specific condition keys exist for individual services. For example, S3 offers s3:x-amz-acl for ACL conditions, while EC2 provides ec2:InstanceType for instance restrictions.
Multiple conditions can be combined using AND logic (all conditions must be true) or within the same operator using OR logic (any value can match). The IfExists suffix allows conditions to pass when the key is not present in the request context.
Practical use cases include restricting API calls to specific VPCs, enforcing MFA for sensitive operations, limiting access during business hours, requiring encryption for data transfers, and implementing tag-based access control.
Understanding conditions is essential for implementing least-privilege access and meeting compliance requirements in AWS environments.
IAM Policy Conditions - AWS Developer Associate Guide
Why IAM Policy Conditions Are Important
IAM policy conditions are a critical security feature that allows you to add fine-grained access control to your AWS resources. They enable you to specify when a policy should be applied, not just what actions are allowed or denied. This granular control is essential for implementing the principle of least privilege and meeting compliance requirements.
What Are IAM Policy Conditions?
Conditions are optional elements in IAM policies that let you specify circumstances under which a policy grants or denies permission. They use condition operators to compare keys and values, determining whether the policy statement applies to a given request.
A condition block contains: - Condition Operator: Defines how to compare values (e.g., StringEquals, DateGreaterThan) - Condition Key: The attribute to evaluate (e.g., aws:SourceIp, s3:prefix) - Condition Value: The value to compare against
How IAM Policy Conditions Work
Basic Syntax:{ "Condition": { "ConditionOperator": { "ConditionKey": "ConditionValue" } }} Common Condition Operators: - StringEquals / StringNotEquals: Case-sensitive exact string matching - StringLike / StringNotLike: Case-sensitive matching with wildcards (* and ?) - NumericEquals / NumericLessThan: Numeric comparisons - DateEquals / DateLessThan: Date/time comparisons - Bool: Boolean matching - IpAddress / NotIpAddress: IP address or range matching - ArnEquals / ArnLike: ARN pattern matching - Null: Checks if a key exists
Global Condition Keys (aws: prefix): - aws:SourceIp: Restrict by IP address - aws:CurrentTime: Time-based restrictions - aws:SecureTransport: Require HTTPS - aws:MultiFactorAuthPresent: Require MFA - aws:PrincipalTag: Match principal tags - aws:RequestedRegion: Restrict by region - aws:username: Match IAM username
Multiple Conditions: - Multiple conditions within the same operator block use AND logic - Multiple operators in the same condition block also use AND logic - To achieve OR logic, create separate statements
Practical Examples:
1. Restrict S3 access to specific IP range: "Condition": {"IpAddress": {"aws:SourceIp": "192.168.1.0/24"}} 2. Require MFA for sensitive operations: "Condition": {"Bool": {"aws:MultiFactorAuthPresent": "true"}} 3. Enforce HTTPS only: "Condition": {"Bool": {"aws:SecureTransport": "true"}} 4. Time-based access: "Condition": {"DateGreaterThan": {"aws:CurrentTime": "2024-01-01T00:00:00Z"}} Exam Tips: Answering Questions on IAM Policy Conditions
1. Know the common condition keys: Focus on aws:SourceIp, aws:MultiFactorAuthPresent, aws:SecureTransport, and aws:PrincipalTag as these appear frequently in exam scenarios.
2. Understand operator behavior: StringEquals is case-sensitive while StringEqualsIgnoreCase is not. StringLike supports wildcards but StringEquals does not.
3. Remember AND vs OR logic: All conditions within a single statement must be true (AND). For OR logic, use multiple statements.
4. MFA scenarios: When a question asks about requiring additional authentication for sensitive actions, look for aws:MultiFactorAuthPresent condition.
5. IP restriction questions: Use IpAddress/NotIpAddress operators with aws:SourceIp key for network-based access control.
6. S3 fine-grained access: Look for s3:prefix conditions when questions involve restricting access to specific folders or object paths.
7. DynamoDB row-level security: dynamodb:LeadingKeys is used for partition key-based access control in DynamoDB.
8. Null condition check: Use {"Null": {"aws:TokenIssueTime": "true"}} to check if temporary credentials were used.
9. Read conditions carefully: Pay attention to whether the condition uses Allow or Deny effect, as this changes the outcome significantly.
10. ForAllValues vs ForAnyValue: ForAllValues requires all request values to match; ForAnyValue requires at least one match. These set operators are commonly tested.