feat(CKV_AWS_341): ensure IAM role max session duration does not exceed 1 hour

Author: Sage-Canty

checkov/terraform/checks/resource/aws/IAMRoleMaxSessionDuration.py

@@ -0,0 +1,47 @@
+from checkov.common.models.enums import CheckCategories, CheckResult
+from checkov.terraform.checks.resource.base_resource_check import BaseResourceCheck
+
+MAX_SESSION_DURATION = 3600  # 1 hour in seconds
+
+
+class IAMRoleMaxSessionDuration(BaseResourceCheck):
+    def __init__(self):
+        name = "Ensure IAM role max session duration does not exceed 1 hour"
+        id = "CKV_AWS_341"
+        supported_resources = ["aws_iam_role"]
+        categories = [CheckCategories.IAM]
+        super().__init__(name=name, id=id, categories=categories, supported_resources=supported_resources)
+
+    def scan_resource_conf(self, conf):
+        """
+        Looks for max_session_duration in aws_iam_role resources.
+        https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/iam_role
+
+        The default value in AWS is 3600 seconds (1 hour).
+        Allowing sessions longer than 1 hour increases the blast radius
+        of a compromised credential.
+
+        Pass: max_session_duration is not set (defaults to 3600) or is <= 3600
+        Fail: max_session_duration is set to a value > 3600
+        """
+        max_session_duration = conf.get("max_session_duration")
+
+        # not set — defaults to 3600, passes
+        if not max_session_duration:
+            return CheckResult.PASSED
+
+        # handle list wrapping from Terraform parser
+        if isinstance(max_session_duration, list):
+            max_session_duration = max_session_duration[0]
+
+        # skip if variable reference (can't evaluate at scan time)
+        if not isinstance(max_session_duration, int):
+            return CheckResult.UNKNOWN
+
+        if max_session_duration <= MAX_SESSION_DURATION:
+            return CheckResult.PASSED
+
+        return CheckResult.FAILED
+
+
+scanner = IAMRoleMaxSessionDuration()

tests/terraform/checks/resource/aws/test_IAMRoleMaxSessionDuration.py

@@ -0,0 +1,71 @@
+import unittest
+from pathlib import Path
+
+from checkov.terraform.checks.resource.aws.IAMRoleMaxSessionDuration import scanner
+from checkov.common.models.enums import CheckResult
+
+
+class TestIAMRoleMaxSessionDuration(unittest.TestCase):
+
+    def test_success_no_max_session_duration(self):
+        """Role with no max_session_duration set — defaults to 3600, should pass."""
+        resource_conf = {
+            "name": ["test_role"],
+            "assume_role_policy": ['{"Version":"2012-10-17"}'],
+        }
+        result = scanner.scan_resource_conf(conf=resource_conf)
+        self.assertEqual(result, CheckResult.PASSED)
+
+    def test_success_max_session_duration_3600(self):
+        """Role with max_session_duration exactly 3600 — should pass."""
+        resource_conf = {
+            "name": ["test_role"],
+            "assume_role_policy": ['{"Version":"2012-10-17"}'],
+            "max_session_duration": [3600],
+        }
+        result = scanner.scan_resource_conf(conf=resource_conf)
+        self.assertEqual(result, CheckResult.PASSED)
+
+    def test_success_max_session_duration_1800(self):
+        """Role with max_session_duration below 3600 — should pass."""
+        resource_conf = {
+            "name": ["test_role"],
+            "assume_role_policy": ['{"Version":"2012-10-17"}'],
+            "max_session_duration": [1800],
+        }
+        result = scanner.scan_resource_conf(conf=resource_conf)
+        self.assertEqual(result, CheckResult.PASSED)
+
+    def test_failure_max_session_duration_7200(self):
+        """Role with max_session_duration of 7200 (2 hours) — should fail."""
+        resource_conf = {
+            "name": ["test_role"],
+            "assume_role_policy": ['{"Version":"2012-10-17"}'],
+            "max_session_duration": [7200],
+        }
+        result = scanner.scan_resource_conf(conf=resource_conf)
+        self.assertEqual(result, CheckResult.FAILED)
+
+    def test_failure_max_session_duration_43200(self):
+        """Role with max_session_duration of 43200 (12 hours, AWS max) — should fail."""
+        resource_conf = {
+            "name": ["test_role"],
+            "assume_role_policy": ['{"Version":"2012-10-17"}'],
+            "max_session_duration": [43200],
+        }
+        result = scanner.scan_resource_conf(conf=resource_conf)
+        self.assertEqual(result, CheckResult.FAILED)
+
+    def test_unknown_variable_reference(self):
+        """Role with max_session_duration as a variable reference — should be UNKNOWN."""
+        resource_conf = {
+            "name": ["test_role"],
+            "assume_role_policy": ['{"Version":"2012-10-17"}'],
+            "max_session_duration": ["${var.max_session_duration}"],
+        }
+        result = scanner.scan_resource_conf(conf=resource_conf)
+        self.assertEqual(result, CheckResult.UNKNOWN)
+
+
+if __name__ == "__main__":
+    unittest.main()