F-01 — Cross-tenant file disclosure via shared /tmp on alwaysdata SSH host `ssh1`
METADATA-ONLY scope evidence.  Collected 2026-07-02.

IMPORTANT ETHICS NOTE
=====================
The ONLY file content read during this research was the researcher's own
canary file, written by Account A (steve-william) and read by Account B
(test-domain) — both accounts owned by the researcher. Everything below
about OTHER customers is METADATA ONLY: filename, owner, mode, size, and
the readability bit from `[ -r "$f" ]`. No third-party file CONTENT was
read, exfiltrated, or retained, per the program's "do not exfiltrate /
do not retain sensitive information" rule.


HOST / KERNEL
=============
Physical SSH host : ssh1
Kernel            : 6.18.30-alwaysdata
Reached via       : ssh-<slug>.alwaysdata.net
  Account A (writer) : ssh-steve-william.alwaysdata.net  slug steve-william  uid 530469  -> ssh1
  Account B (reader) : ssh-test-domain.alwaysdata.net    slug test-domain    uid 530478  -> ssh1
                       (Account B is a DIFFERENT customer / UID from Account A)


ISOLATION BOUNDARIES THAT ARE INTACT (narrows finding to /tmp only)
===================================================================
/home directory    : mode 711  -> cannot be listed
per-account home   : mode 770  -> NOT readable by other accounts (home isolation OK)
882 account home directories present on ssh1 (from `ls /home | wc -l` count only)
process isolation  : hidepid in effect -> an account sees only its own processes
/proc environ leak : 0 (no cross-account /proc/<pid>/environ leakage)


THE BROKEN BOUNDARY — SHARED /tmp
=================================
/tmp mode          : drwxrwxrwt (1777) — shared by ALL accounts, NOT polyinstantiated
platform umask     : 0022  (observed from Account B: `umask` -> 0022)
new-file mode      : a freshly created /tmp file lands mode 644 (world-readable)
                     e.g. Account B's own new /tmp file: owner test-domain mode 644

/tmp population at test time:
  total files      : 203
  distinct owners  : 48

Readability of OTHER tenants' /tmp files, from Account B
(verified via `[ -r "$f" ]` — a permission test, NOT a content read):
  READABLE files   : 65
  distinct OTHER live customer accounts owning those readable files : 12

  Owner breakdown of the 65 readable files (owner -> file count where noted):
    clariback              20
    attatcn                19
    storioscope_ssh        11
    dhiaa_Admin             5
    lycotech                (readable)
    yes                     (readable)
    xtn                     (readable)
    orbitechmaintanance     (readable)
    nerudaarchives_codex    (readable)
    indio                   (readable)
    ( + additional owners rounding out the 12 distinct accounts / 65 files )


CANARY PROOF (researcher-owned, cross-tenant read)
==================================================
Step 1 (as Account A, steve-william, uid 530469):
  echo "CANARY_A_secret_9f2b7c1e_ONLY_A_WROTE_THIS :: written by account steve-william(A) at <date> uid=530469" \
    > /tmp/CANARY_A_secret_9f2b7c1e_ONLY_A_WROTE_THIS.txt
  chmod 644 /tmp/CANARY_A_secret_9f2b7c1e_ONLY_A_WROTE_THIS.txt
  -> file created: owner steve-william, mode 644

Step 2 (as Account B, test-domain, uid 530478 — different tenant):
  stat /tmp/CANARY_A_secret_9f2b7c1e_ONLY_A_WROTE_THIS.txt
    -> owner=steve-william  mode=644   (B sees a file it does not own)
  cat  /tmp/CANARY_A_secret_9f2b7c1e_ONLY_A_WROTE_THIS.txt
    -> "CANARY_A_secret_9f2b7c1e_ONLY_A_WROTE_THIS :: written by account
        steve-william(A) at Thu Jul  2 12:45:53 UTC 2026 uid=530469"
  => Account B read Account A's file across the tenant boundary. CONFIRMED.


/tmp LISTING SAMPLE — filenames + owners + perms ONLY (no content read)
======================================================================
Sensitive filename CLASSES observed on other tenants (metadata only):

  owner attatcn:
    -rw-r--r-- attatcn  inject_config.py                 (config script)

  owner storioscope_ssh:
    -rw-r--r-- storioscope_ssh  storioscope-security-*.tgz       (~41-108 KB source archive)
    -rw-r--r-- storioscope_ssh  storioscope-pre-security-*.tgz   (source archive)

  owner nerudaarchives_codex:
    -rw-r--r-- nerudaarchives_codex  omeka_db_env_2388891         (database env file)

  owner benech:
    -rw-r--r-- benech   att_fin_798.pdf                  (financial PDF)
    -rw-r--r-- benech   att_fin_839.pdf                  (financial PDF)

  owner avioeroon:
    -rw-r--r-- avioeroon  bitcoin-local-backup-*          (crypto wallet backup)
    -rw-r--r-- avioeroon  bitcoin-next.log                (crypto log)

NOTE: all lines above are `ls -l` / `stat` metadata (name, owner, mode, size).
No byte of any of these third-party files was ever read or stored.


ESCALATION (identified, NOT exploited against real victims)
===========================================================
A world-readable DB `.env` / config file in /tmp would yield DB credentials.
alwaysdata DB endpoints are remotely reachable:
    mysql-<account>.alwaysdata.net:3306
    postgresql-<account>.alwaysdata.net:5432
=> passive /tmp read could pivot into another tenant's database.
This escalation was NOT performed against any real victim.


PRIOR ART CHECK
===============
Not present in the public Flyspray tracker (FS#333–362).