cloud-bucket-brute

Contents

• Scope & authorization
• Name permutation scheme
• Probe logic
• Runnable snippets
• Output
• Reference file: references/cloud-storage-endpoints.md

Scope & authorization

Run only against organizations you own or are contractually engaged to test. This is an aggressive-3rdparty check: it does not touch the target's own infrastructure, but it fires a high volume of requests at third-party cloud providers (AWS/GCP/DigitalOcean/Alibaba/Oracle/Vultr) about the target. Expect provider-side rate-limiting and logging. Keep the candidate list scoped to the org actually in scope.

Input is the set of the target's domains. Output is any bucket name that resolves to an anonymously reachable object store.

Name permutation scheme

Turn each in-scope domain into candidate bucket names (this is the valuable part - carry it exactly):

1. Reduce the domain to its registrable root label (tldextract(...).domain, e.g. foo-bar.co.uk -> foo-bar) and seed the variation set with the raw name.
2. If the root contains -, split into name + second_name, and also add the initials name[0]+second_name[0].
3. For each "common company word" that appears inside the root (company, group, tech, solutions, international, services, world, global, ai, io, team, inc, ask, digital, data, bits, bit, open, edu, educaiton, learning, auto, stack), add the name with that word stripped out, plus the initials of the two parts around it. (So bugcrowd yields bugcrowd, bug/crowd fragments, bc, etc.)
4. Expand every variation through the permutation templates against the suffix wordlist. Bare {name} is always tried; multi-word templates ({name}_{word}, {word}-{name}, {word}_{name}, {name}{word}, {name}{second_name}, {name}{second_name}-{word}, {name}{second_name}_{word}, {name}-{second_name}-{word}, {name}_{second_name}_{word}, {name}{second_name}{word}) are only applied to non-domain-looking single/two-part variations.

The full provider endpoint templates, per-provider fail indications, region lists, the 40-word suffix list, and the permutation templates are in references/cloud-storage-endpoints.md.

Probe logic

For each candidate: GET the endpoint (5s timeout). Parse the body as XML/JSON/text by Content-Type. By default pick one random region per region-templated endpoint (set an "iterate all regions" flag only for a deep, much slower pass). Discard any response containing that provider's fail indications (e.g. AWS AccessDenied, NoSuchBucket, IllegalLocationConstraintException, AllAccessDisabled, PermanentRedirect; GCP The specified bucket does not exist / Anonymous caller does not have storage.buckets.get; Oracle AnonymousUserSubject; Vultr/DO NoSuchBucket), and discard any body containing Burp Suite Professional (interception artifact).

Report a finding when: an endpoint returns a body with none of its fail indications - the bucket exists and is anonymously reachable. Severity: Information Disclosure (verify listability/read of objects before rating impact).

Runnable snippets

# single candidate, AWS virtual-host + GCP JSON API
NAME=acme-backups
curl -s "https://$NAME.s3.amazonaws.com" | grep -qiE 'AccessDenied|NoSuchBucket|IllegalLocationConstraint|AllAccessDisabled' \
  && echo "aws: not public" || echo "aws: PUBLIC/exists -> https://$NAME.s3.amazonaws.com"
curl -s "https://www.googleapis.com/storage/v1/b/$NAME" | grep -qiE 'does not exist|does not have storage.buckets.get' \
  && echo "gcp: not public" || echo "gcp: PUBLIC/exists"

# generate candidate names (permutation scheme) for a domain
python3 - <<'PY'
import tldextract
words=["archive","artifacts","assets","backup","bin","bucket","data","dev","dev-data","dev_data","devops","files","git","it","logs","media","mediauploads","onboarding","ops","proj","project","prod","prod-data","prod_data","prod-files","prod_files","reports","scripts","stage","staging","static","storage","temp","terraform","tf","tf-files","tf_files","terraformbinaries","test","tmp","user-files","user_files","uploads"]
common={"company","group","tech","solutions","international","services","world","global","ai","io","team","inc","ask","digital","data","bits","bit","open","edu","educaiton","learning","auto","stack"}
name=tldextract.extract("acme-corp.com").domain
variations=[(name,)]
if "-" in name:
    a,b=name.split("-",1); variations+=[(a,b),(a[0]+b[0],)]
for w in common:
    if w in name:
        variations+=[(name.replace(w,""),)]
tmpl_base=["{name}"]
tmpl_multi=["{name}_{word}","{word}-{name}","{word}_{name}","{name}{word}","{name}{second_name}","{name}{second_name}-{word}","{name}{second_name}_{word}","{name}-{second_name}-{word}","{name}_{second_name}_{word}","{name}{second_name}{word}"]
out=[]
for v in variations:
    tmpls=tmpl_base+(tmpl_multi if len(v)<=2 else [])
    for w in words:
        for t in tmpls:
            if "{second_name}" in t and len(v)!=2: continue
            s=t.replace("{name}",v[0]).replace("{word}",w)
            if len(v)==2: s=s.replace("{second_name}",v[1])
            if s not in out: out.append(s)
print("\n".join(out))
PY

Output

Finish with a candidate / provider / reachable? ledger (or just the confirmed hits when the candidate list is large), then a verdict:

• Clean - candidates generated and probed across all six providers, nothing anonymously reachable.
• Exposed - list each public bucket URL, its provider, and whether objects are listable/readable. Fix: make buckets private, require authentication, and audit bucket-policy/ACL for anonymous grants.

Report whether the sweep was rate-limited or partial (e.g. one-region-only), so an incomplete run is not reported as clean.