IAM deny policies in GCP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the effect of the deny policy.

GCP

{
  "denyRule": {
    "deniedPermissions": ["storage.buckets.delete"],
    "denialCondition": {
      "expression": "request.time < timestamp('2025-01-01T00:00:00Z')"
    },
    "[1]": "DENY"
  }
}

Drag options to blanks, or click blank then click option'

Aaction

Beffect

Cpermission

Drole

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'action' instead of 'effect' causes the policy to be invalid.

Confusing 'role' with the effect key.

The key effect defines whether the policy denies or allows the specified permissions. For deny policies, it must be set to DENY.

2fill in blank

medium

Complete the code to specify the permissions to deny in the deny rule.

GCP

{
  "denyRule": {
    "[1]": ["compute.instances.delete", "compute.instances.stop"]
  }
}

Drag options to blanks, or click blank then click option'

AallowedPermissions

Bpermissions

CdeniedPermissions

DblockedActions

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'allowedPermissions' which is for allow policies.

Using 'permissions' which is too generic and invalid here.

The key deniedPermissions lists the permissions that the deny policy blocks.

3fill in blank

hard

Fix the error in the condition expression to correctly deny before 2024-12-31.

GCP

{
  "denyRule": {
    "deniedPermissions": ["storage.objects.delete"],
    "denialCondition": {
      "expression": "request.time [1] timestamp('2024-12-31T23:59:59Z')"
    }
  }
}

Drag options to blanks, or click blank then click option'

A<

B!=

C==

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' which denies after the date instead of before.

Using '==' which only denies at the exact time.

The expression uses < to deny actions before the specified timestamp.

4fill in blank

hard

Fill both blanks to create a deny policy that blocks deleting buckets and objects.

GCP

{
  "denyRule": {
    "[1]": ["storage.buckets.delete"],
    "[2]": ["storage.objects.delete"]
  }
}

Drag options to blanks, or click blank then click option'

AdeniedPermissions

BallowedPermissions

Dpermissions

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'allowedPermissions' which is incorrect for deny rules.

Using 'permissions' which is not a valid key here.

Both blanks require the key deniedPermissions to specify the permissions to deny.

5fill in blank

hard

Fill all three blanks to create a deny policy with a condition that denies stopping and deleting compute instances before 2025.

GCP

{
  "denyRule": {
    "[1]": ["compute.instances.stop"],
    "[2]": ["compute.instances.delete"],
    "denialCondition": {
      "expression": "request.time [3] timestamp('2025-01-01T00:00:00Z')"
    }
  }
}

Drag options to blanks, or click blank then click option'

AdeniedPermissions

BallowedPermissions

C<

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'allowedPermissions' which is invalid for deny rules.

Using '>' operator which denies after the date.

Both permission lists use deniedPermissions and the condition uses < to deny before the date.

Practice

1. What is the main purpose of an IAM deny policy in Google Cloud?

easy

A. To monitor user activities without changing permissions

B. To grant additional permissions to users or groups

C. To explicitly block certain permissions even if other policies allow them

D. To automatically delete unused resources

Solution

1. Step 1: Understand IAM deny policy function and compare with other policy types

   An IAM deny policy explicitly blocks permissions, overriding any allow policies. Unlike allow policies that grant access, deny policies prevent actions even if allowed elsewhere.

2. Final Answer:

   To explicitly block certain permissions even if other policies allow them -> Option C

3. Quick Check:

   IAM deny policy blocks permissions [OK]

Hint: Deny policies block permissions regardless of other allows [OK]

Common Mistakes:

• Confusing deny policies with allow policies
• Thinking deny policies grant permissions
• Assuming deny policies only monitor actions

2. Which of the following is the correct way to specify a deny rule in an IAM policy JSON snippet?

easy

A. "denyRules": [{"deniedPermissions": ["storage.buckets.delete"]}]

B. "allowRules": [{"allowedPermissions": ["storage.buckets.delete"]}]

C. "denyRules": [{"allowedPermissions": ["storage.buckets.delete"]}]

D. "denyRules": [{"deniedPermissions": "storage.buckets.delete"}]

Solution

1. Step 1: Identify correct deny rule syntax and check each option

   Deny rules use "denyRules" with "deniedPermissions" as a list of strings. "denyRules": [{"deniedPermissions": ["storage.buckets.delete"]}] correctly uses a list for "deniedPermissions". "allowRules": [{"allowedPermissions": ["storage.buckets.delete"]}] uses allowRules, which is incorrect. "denyRules": [{"allowedPermissions": ["storage.buckets.delete"]}] mixes denyRules with allowedPermissions, which is invalid. "denyRules": [{"deniedPermissions": "storage.buckets.delete"}] uses a string instead of a list, which is invalid.

2. Final Answer:

   "denyRules": [{"deniedPermissions": ["storage.buckets.delete"]}] -> Option A

3. Quick Check:

   Deny rules need deniedPermissions as list [OK]

Hint: Deny permissions must be in a list under deniedPermissions [OK]

Common Mistakes:

• Using allowRules instead of denyRules
• Providing deniedPermissions as a string instead of list
• Mixing allowedPermissions inside denyRules

3. Given this deny policy snippet:

{"denyRules": [{"deniedPermissions": ["compute.instances.start"]}]}

What happens if a user has an allow policy for compute.instances.start but this deny policy is applied?

medium

A. The user can start instances because allow policies override deny policies

B. The deny policy has no effect unless combined with a condition

C. The user can start instances only during business hours

D. The user cannot start instances because deny policies block the permission

Solution

1. Step 1: Understand deny policy precedence and apply to the example

   Deny policies always override allow policies for the specified permissions. Even if the user has an allow for starting instances, the deny rule blocks it.

2. Final Answer:

   The user cannot start instances because deny policies block the permission -> Option D

3. Quick Check:

   Deny overrides allow for blocked permissions [OK]

Hint: Deny always beats allow for the same permission [OK]

Common Mistakes:

• Thinking allow policies override deny policies
• Assuming deny policies need conditions to work
• Believing deny policies only log actions

4. You wrote this deny policy JSON but it does not block the intended permission:

{"denyRules": [{"deniedPermissions": "storage.objects.delete"}]}

What is the error?

medium

A. denyRules should be named allowRules

B. deniedPermissions should be a list, not a string

C. storage.objects.delete is not a valid permission

D. The policy must include a condition to work

Solution

1. Step 1: Check deniedPermissions data type and identify the error in the JSON

   deniedPermissions must be a list of strings, not a single string. The policy uses a string instead of a list, so it is invalid and won't block the permission.

2. Final Answer:

   deniedPermissions should be a list, not a string -> Option B

3. Quick Check:

   deniedPermissions requires a list [OK]

Hint: Use brackets [] for deniedPermissions list [OK]

Common Mistakes:

• Using string instead of list for deniedPermissions
• Confusing denyRules with allowRules
• Thinking conditions are mandatory

5. You want to deny the permission storage.buckets.delete only for requests made after 2024-01-01T00:00:00Z. Which IAM deny policy condition should you use?

hard

A. Use a condition with request.time > '2024-01-01T00:00:00Z'

B. Use a condition with resource.name == 'storage.buckets.delete'

C. No condition is needed; deny applies to all users

D. Use a condition with request.ip != 'company-network-ip-range'

Solution

1. Step 1: Identify the condition to restrict by time and match condition syntax

   To deny only for requests after the date, use a condition checking request.time > '2024-01-01T00:00:00Z'. Use a condition with request.time > '2024-01-01T00:00:00Z' uses request.time with inequality to apply after the date, which is correct.

2. Final Answer:

   Use a condition with request.time > '2024-01-01T00:00:00Z' -> Option A

3. Quick Check:

   Condition on request.time restricts deny by time [OK]

Hint: Use request.time condition to limit deny by time [OK]

Common Mistakes:

• Using resource.name instead of request.time for time check
• Using IP condition unrelated to time
• Applying deny without condition blocks all users