DataDog · xathrya · Mar 5, 2025
diff --git a/docs/attack-techniques/GCP/gcp.exfiltration.gcs-backdoor-bucket-policy.md b/docs/attack-techniques/GCP/gcp.exfiltration.gcs-backdoor-bucket-policy.md
@@ -0,0 +1,82 @@
+---
+title: Backdoor a Cloud Storage bucket via its bucket policy
+---
+
+# Backdoor a Cloud Storage bucket via its bucket policy
+
+<span class="smallcaps w3-badge w3-blue w3-round w3-text-white" title="This attack technique can be detonated multiple times">idempotent</span> 
+
+Platform: GCP
+
+## MITRE ATT&CK Tactics
+
+
+- Exfiltration
+
+## Description
+
+
+Exfiltrates data from a Cloud Storage bucket by backdooring its policy to allow access from an external, fictitious GCP account.
+
+<span style="font-variant: small-caps;">Warm-up</span>:
+
+- Create a Cloud Storage bucket
+
+<span style="font-variant: small-caps;">Detonation</span>:
+
+- Backdoor the IAM policy of the bucket to grant the role `storage.objectAdmin` to a fictitious attacker
+
+!!! info
+
+  Since the target e-mail must exist for this attack simulation to work, Stratus Red Team grants the role to [email protected] 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:
+
+  ```bash
+  export STRATUS_RED_TEAM_ATTACKER_EMAIL="[email protected]"
+  stratus detonate gcp.exfiltration.gcs-backdoor-bucket-policy
+  ```
+
+
+## Instructions
+
+```bash title="Detonate with Stratus Red Team"
+stratus detonate gcp.exfiltration.gcs-backdoor-bucket-policy
+```
+## Detection
+
+
+Granting IAM role to account is detected as 'storage.setIamPolicy' in Cloud Logging.
+
+Data Access logging for GCS bucket is disabled by default, thus we need to enable it (if not enabled).
+
+- Go to "IAM & Admin" -> "Audit Logs"
+- Locate "Google Cloud Storage"
+- on "Permission Types", check the "Admin read"
+
+You can use following query to filter the events:
+
+```
+resource.type="gcs_bucket"
+protoPayload.serviceName="storage.googleapis.com"
+protoPayload.methodName="storage.setIamPermissions"
+```
+
+Sample event (shortened for readability):
+
+```json
+{
+  "logName": "projects/my-project-id/logs/cloudaudit.googleapis.com%2Factivity",
+  "protoPayload": {
+    "authenticationInfo": {
+      "principalEmail": "[email protected]",
+    },
+    "methodName": "storage.setIamPermissions",
+    "resourceName": "projects/_/buckets/my-bucket-id",
+    "serviceName": "storage.googleapis.com",
+  },
+  "resource": {
+    "type": "gcs_bucket"
+  },
+  "severity": "NOTICE"
+}
diff --git a/docs/attack-techniques/GCP/index.md b/docs/attack-techniques/GCP/index.md
@@ -11,6 +11,8 @@ Note that some Stratus attack techniques may correspond to more than a single AT
 
 ## Exfiltration
 
+- [Backdoor an S3 Bucket via its Bucket Policy](./gcp.exfiltration.gcs-backdoor-bucket-policy.md)
+
 - [Exfiltrate Compute Disk by sharing it](./gcp.exfiltration.share-compute-disk.md)
 
 - [Exfiltrate Compute Image by sharing it](./gcp.exfiltration.share-compute-image.md)

diff --git a/docs/attack-techniques/list.md b/docs/attack-techniques/list.md
@@ -64,6 +64,7 @@ This page contains the list of all Stratus Attack Techniques.
 | [Create Application](./entra-id/entra-id.persistence.new-application.md) | [Entra ID](./entra-id/index.md) | Persistence, Privilege Escalation |
 | [Create Sticky Backdoor User Through Restricted Management AU](./entra-id/entra-id.persistence.restricted-au.md) | [Entra ID](./entra-id/index.md) | Persistence |
 | [Retrieve a High Number of Secret Manager secrets](./GCP/gcp.credential-access.secretmanager-retrieve-secrets.md) | [GCP](./GCP/index.md) | Credential Access |
+| [Backdoor a Cloud Storage Bucket via its bucket policy](./GCP/gcp.exfiltration.gcs-backdoor-bucket-policy.md) | [GCP](./GCP/index.md) | Exfiltration |
 | [Exfiltrate Compute Disk by sharing it](./GCP/gcp.exfiltration.share-compute-disk.md) | [GCP](./GCP/index.md) | Exfiltration |
 | [Exfiltrate Compute Image by sharing it](./GCP/gcp.exfiltration.share-compute-image.md) | [GCP](./GCP/index.md) | Exfiltration |
 | [Exfiltrate Compute Disk by sharing a snapshot](./GCP/gcp.exfiltration.share-compute-snapshot.md) | [GCP](./GCP/index.md) | Exfiltration |

diff --git a/docs/index.yaml b/docs/index.yaml
@@ -394,6 +394,13 @@ GCP:
           platform: GCP
           isIdempotent: true
     Exfiltration:
+        - id: gcp.exfiltration.gcs-backdoor-bucket-policy
+          name: Backdoor a Cloud Storage bucket via its bucket policy
+          isSlow: false
+          mitreAttackTactics:
+            - Exfiltration
+          platform: GCP
+          isIdempotent: true
         - id: gcp.exfiltration.share-compute-disk
           name: Exfiltrate Compute Disk by sharing it
           isSlow: false

diff --git a/v2/go.mod b/v2/go.mod
@@ -51,12 +51,19 @@ require (
 )
 
 require (
+	cel.dev/expr v0.19.0 // indirect
+	cloud.google.com/go v0.118.0 // indirect
 	cloud.google.com/go/auth v0.14.0 // indirect
 	cloud.google.com/go/auth/oauth2adapt v0.2.7 // indirect
 	cloud.google.com/go/compute/metadata v0.6.0 // indirect
 	cloud.google.com/go/iam v1.3.1 // indirect
+	cloud.google.com/go/monitoring v1.23.0 // indirect
+	cloud.google.com/go/storage v1.50.0 // indirect
 	github.com/Azure/azure-sdk-for-go/sdk/internal v1.10.0 // indirect
 	github.com/AzureAD/microsoft-authentication-library-for-go v1.2.2 // indirect
+	github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.25.0 // indirect
+	github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/metric v0.48.1 // indirect
+	github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapping v0.48.1 // indirect
 	github.com/ProtonMail/go-crypto v1.1.0-alpha.2 // indirect
 	github.com/PuerkitoBio/purell v1.1.1 // indirect
 	github.com/PuerkitoBio/urlesc v0.0.0-20170810143723-de5bf2ad4578 // indirect
@@ -73,10 +80,14 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/internal/s3shared v1.18.13 // indirect
 	github.com/aws/aws-sdk-go-v2/service/sso v1.24.15 // indirect
 	github.com/aws/aws-sdk-go-v2/service/ssooidc v1.28.14 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/cjlapao/common-go v0.0.39 // indirect
 	github.com/cloudflare/circl v1.3.7 // indirect
+	github.com/cncf/xds/go v0.0.0-20240905190251-b4127c9b8d78 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/emicklei/go-restful/v3 v3.8.0 // indirect
+	github.com/envoyproxy/go-control-plane/envoy v1.32.4 // indirect
+	github.com/envoyproxy/protoc-gen-validate v1.2.1 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
 	github.com/go-logr/logr v1.4.2 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
@@ -112,16 +123,20 @@ require (
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c // indirect
+	github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/rivo/uniseg v0.2.0 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
 	github.com/std-uritemplate/std-uritemplate/go v0.0.57 // indirect
 	github.com/stretchr/objx v0.5.2 // indirect
 	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
+	go.opentelemetry.io/contrib/detectors/gcp v1.32.0 // indirect
 	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.58.0 // indirect
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.58.0 // indirect
 	go.opentelemetry.io/otel v1.34.0 // indirect
 	go.opentelemetry.io/otel/metric v1.34.0 // indirect
+	go.opentelemetry.io/otel/sdk v1.34.0 // indirect
+	go.opentelemetry.io/otel/sdk/metric v1.32.0 // indirect
 	go.opentelemetry.io/otel/trace v1.34.0 // indirect
 	golang.org/x/mod v0.17.0 // indirect
 	golang.org/x/net v0.34.0 // indirect

diff --git a/v2/go.sum b/v2/go.sum
@@ -1,3 +1,5 @@
+cel.dev/expr v0.19.0 h1:lXuo+nDhpyJSpWxpPVi5cPUwzKb+dsdOiw6IreM5yt0=
+cel.dev/expr v0.19.0/go.mod h1:MrpN08Q+lEBs+bGYdLxxHkZoUSsCp0nSKTs0nTymJgw=
 cloud.google.com/go v0.26.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
 cloud.google.com/go v0.118.0 h1:tvZe1mgqRxpiVa3XlIGMiPcEUbP1gNXELgD4y/IXmeQ=
 cloud.google.com/go v0.118.0/go.mod h1:zIt2pkedt/mo+DQjcT4/L3NDxzHPR29j5HcclNH+9PM=
@@ -11,8 +13,12 @@ cloud.google.com/go/compute/metadata v0.6.0 h1:A6hENjEsCDtC1k8byVsgwvVcioamEHvZ4
 cloud.google.com/go/compute/metadata v0.6.0/go.mod h1:FjyFAW1MW0C203CEOMDTu3Dk1FlqW3Rga40jzHL4hfg=
 cloud.google.com/go/iam v1.3.1 h1:KFf8SaT71yYq+sQtRISn90Gyhyf4X8RGgeAVC8XGf3E=
 cloud.google.com/go/iam v1.3.1/go.mod h1:3wMtuyT4NcbnYNPLMBzYRFiEfjKfJlLVLrisE7bwm34=
+cloud.google.com/go/monitoring v1.23.0 h1:M3nXww2gn9oZ/qWN2bZ35CjolnVHM3qnSbu6srCPgjk=
+cloud.google.com/go/monitoring v1.23.0/go.mod h1:034NnlQPDzrQ64G2Gavhl0LUHZs9H3rRmhtnp7jiJgg=
 cloud.google.com/go/secretmanager v1.14.4 h1:SMWQMsUcACsdIuVhIBAw+QfKY4Xseiaa8qDnunjmhcM=
 cloud.google.com/go/secretmanager v1.14.4/go.mod h1:pjwFw8+A6B4AcWrVXruLfz1QykkpMr8T/VT+zXB91iw=
+cloud.google.com/go/storage v1.50.0 h1:3TbVkzTooBvnZsk7WaAQfOsNrdoM8QHusXA1cpk6QJs=
+cloud.google.com/go/storage v1.50.0/go.mod h1:l7XeiD//vx5lfqE3RavfmU9yvk5Pp0Zhcv482poyafY=
 dario.cat/mergo v1.0.0 h1:AGCNq9Evsj31mOgNPcLyXc+4PNABt905YmuqPYYpBWk=
 dario.cat/mergo v1.0.0/go.mod h1:uNxQE+84aUszobStD9th8a29P2fMDhsBdgRYvZOxGmk=
 github.com/Azure/azure-sdk-for-go/sdk/azcore v1.14.0 h1:nyQWyZvwGTvunIMxi1Y9uXkcyr+I7TeNrr/foo4Kpk8=
@@ -40,6 +46,12 @@ github.com/Azure/azure-sdk-for-go/sdk/resourcemanager/resources/armresources v1.
 github.com/AzureAD/microsoft-authentication-library-for-go v1.2.2 h1:XHOnouVk1mxXfQidrMEnLlPk9UMeRtyBTnEFtxkV0kU=
 github.com/AzureAD/microsoft-authentication-library-for-go v1.2.2/go.mod h1:wP83P5OoQ5p6ip3ScPr0BAq0BvuPAvacpEuSzyouqAI=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.25.0 h1:3c8yed4lgqTt+oTQ+JNMDo+F4xprBf+O/il4ZC0nRLw=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.25.0/go.mod h1:obipzmGjfSjam60XLwGfqUkJsfiheAl+TUjG+4yzyPM=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/metric v0.48.1 h1:UQ0AhxogsIRZDkElkblfnwjc3IaltCm2HUMvezQaL7s=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/metric v0.48.1/go.mod h1:jyqM3eLpJ3IbIFDTKVz2rF9T/xWGW0rIriGwnz8l9Tk=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapping v0.48.1 h1:8nn+rsCvTq9axyEh382S0PFLBeaFwNsT43IrPWzctRU=
+github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapping v0.48.1/go.mod h1:viRWSEhtMZqz1rhwmOVKkWl6SwmVowfL9O2YR5gI2PE=
 github.com/Microsoft/go-winio v0.6.1 h1:9/kr64B9VUZrLm5YYwbGtUJnMgqWVOdUAXu6Migciow=
 github.com/Microsoft/go-winio v0.6.1/go.mod h1:LRdKpFKfdobln8UmuiYcKPot9D2v6svN5+sAH+4kjUM=
 github.com/ProtonMail/go-crypto v1.1.0-alpha.2 h1:bkyFVUP+ROOARdgCiJzNQo2V2kiB97LyUpzH9P6Hrlg=
@@ -121,11 +133,15 @@ github.com/aws/smithy-go v1.22.2/go.mod h1:irrKGvNn1InZwb2d7fkIRNucdfwR8R+Ts3wxY
 github.com/cenkalti/backoff/v4 v4.2.1 h1:y4OZtCnogmCPw98Zjyt5a6+QwPLGkiQsYW5oUqylYbM=
 github.com/cenkalti/backoff/v4 v4.2.1/go.mod h1:Y3VNntkOUPxTVeUxJ/G5vcM//AlwfmyYozVcomhLiZE=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
+github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
+github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/cjlapao/common-go v0.0.39 h1:bAAUrj2B9v0kMzbAOhzjSmiyDy+rd56r2sy7oEiQLlA=
 github.com/cjlapao/common-go v0.0.39/go.mod h1:M3dzazLjTjEtZJbbxoA5ZDiGCiHmpwqW9l4UWaddwOA=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
 github.com/cloudflare/circl v1.3.7 h1:qlCDlTPz2n9fu58M0Nh1J/JzcFpfgkFHHX3O35r5vcU=
 github.com/cloudflare/circl v1.3.7/go.mod h1:sRTcRWXGLrKw6yIGJ+l7amYJFfAXbZG0kBSc8r4zxgA=
+github.com/cncf/xds/go v0.0.0-20240905190251-b4127c9b8d78 h1:QVw89YDxXxEe+l8gU8ETbOasdwEV+avkR75ZzsVV9WI=
+github.com/cncf/xds/go v0.0.0-20240905190251-b4127c9b8d78/go.mod h1:W+zGtBO5Y1IgJhy4+A9GOqVhqLpfZi+vwmdNXUehLA8=
 github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/cyphar/filepath-securejoin v0.2.4 h1:Ugdm7cg7i6ZK6x3xDF1oEu1nfkyfH53EtKeQYTC3kyg=
@@ -141,7 +157,13 @@ github.com/emicklei/go-restful/v3 v3.8.0/go.mod h1:6n3XBCmQQb25CM2LCACGz8ukIrRry
 github.com/emirpasic/gods v1.18.1 h1:FXtiHYKDGKCW2KzwZKx0iC0PQmdlorYgdFG9jPXJ1Bc=
 github.com/emirpasic/gods v1.18.1/go.mod h1:8tpGGwCnJ5H4r6BWwaV6OrWmMoPhUl5jm/FMNAnJvWQ=
 github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
+github.com/envoyproxy/go-control-plane v0.13.4 h1:zEqyPVyku6IvWCFwux4x9RxkLOMUL+1vC9xUFv5l2/M=
+github.com/envoyproxy/go-control-plane v0.13.4/go.mod h1:kDfuBlDVsSj2MjrLEtRWtHlsWIFcGyB2RMO44Dc5GZA=
+github.com/envoyproxy/go-control-plane/envoy v1.32.4 h1:jb83lalDRZSpPWW2Z7Mck/8kXZ5CQAFYVjQcdVIr83A=
+github.com/envoyproxy/go-control-plane/envoy v1.32.4/go.mod h1:Gzjc5k8JcJswLjAx1Zm+wSYE20UrLtt7JZMWiWQXQEw=
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
+github.com/envoyproxy/protoc-gen-validate v1.2.1 h1:DEo3O99U8j4hBFwbJfrz9VtgcDfUKS7KJ7spH3d86P8=
+github.com/envoyproxy/protoc-gen-validate v1.2.1/go.mod h1:d/C80l/jxXLdfEIhX1W2TmLfsJ31lvEjwamM4DxlWXU=
 github.com/fatih/color v1.16.0 h1:zmkK9Ngbjj+K0yRhTVONQh1p/HknKYSlNT+vZCzyokM=
 github.com/fatih/color v1.16.0/go.mod h1:fL2Sau1YI5c0pdGEVCbKQbLXB6edEj1ZgiY4NijnWvE=
 github.com/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2Wg=
@@ -296,6 +318,8 @@ github.com/pjbgf/sha1cd v0.3.0/go.mod h1:nZ1rrWOcGJ5uZgEEVL1VUM9iRQiZvWdbZjkKyFz
 github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c h1:+mdjkGKdHQG3305AYmdv1U2eRNDiU2ErMBj1gwrq8eQ=
 github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c/go.mod h1:7rwL4CYBLnjLxUqIJNnCWiEdr3bn6IUYi15bNlnbCCU=
 github.com/pkg/profile v1.6.0/go.mod h1:qBsxPvzyUincmltOk6iyRVxHYg4adc0OFOv72ZdLa18=
+github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 h1:GFCKgmp0tecUJ0sJuv4pzYCqS9+RGSn52M3FUwPs+uo=
+github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10/go.mod h1:t/avpk3KcrXxUnYOhZhMXJlSEyie6gQbtLq5NM3loB8=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
@@ -337,6 +361,8 @@ go.opencensus.io v0.24.0 h1:y73uSU6J157QMP2kn2r30vwW1A2W2WFwSCGnAVxeaD0=
 go.opencensus.io v0.24.0/go.mod h1:vNK8G9p7aAivkbmorf4v+7Hgx+Zs0yY+0fOtgBfjQKo=
 go.opentelemetry.io/auto/sdk v1.1.0 h1:cH53jehLUN6UFLY71z+NDOiNJqDdPRaXzTel0sJySYA=
 go.opentelemetry.io/auto/sdk v1.1.0/go.mod h1:3wSPjt5PWp2RhlCcmmOial7AvC4DQqZb7a7wCow3W8A=
+go.opentelemetry.io/contrib/detectors/gcp v1.32.0 h1:P78qWqkLSShicHmAzfECaTgvslqHxblNE9j62Ws1NK8=
+go.opentelemetry.io/contrib/detectors/gcp v1.32.0/go.mod h1:TVqo0Sda4Cv8gCIixd7LuLwW4EylumVWfhjZJjDD4DU=
 go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.58.0 h1:PS8wXpbyaDJQ2VDHHncMe9Vct0Zn1fEjpsjrLxGJoSc=
 go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.58.0/go.mod h1:HDBUsEjOuRC0EzKZ1bSaRGZWUBAzo+MhAcUUORSr4D0=
 go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.58.0 h1:yd02MEjBdJkG3uabWP9apV+OuWRIXGDuJEUJbOHmCFU=