# Exploit verification ledger

**What this is:** results of actually *running each exploit* against a genuinely
vulnerable VM and confirming `uid=0` **out of band** (an independent root-owned
write / `/etc/shadow` read / setuid-bash sentinel — never the module's own
self-report). This is distinct from `docs/VERIFICATIONS.jsonl`'s historical
records, which only checked that `detect()` returns the right verdict.

Harness: rootless qemu/KVM over frozen point-release cloud images (unpatched →
vulnerable by default), driver in the session scratch dir. Root witnessed via
`witness.sh` (shell-probe + setuid-bash finisher + module sentinels + `/etc/passwd`
tamper check).

> **Headline finding:** the corpus was only ever *detect*-verified, never
> *exploit*-verified. Running the exploits shows a mix of genuinely-working,
> honestly-failing, and **falsely-succeeding** modules. Two flagship modules
> reported `EXPLOIT_OK` while obtaining **no root at all** (`pwnkit`,
> `ptrace_traceme`) — a false positive from the dispatcher's "execve
> transferred → clean child exit = OK" path. Both are addressed below.

## Confirmed landing root (uid=0 witnessed out of band)

| module | CVE | target | notes |
|---|---|---|---|
| `refluxfs` | CVE-2026-64600 | Rocky 9.8 / 5.14.0-687.el9 | full chain, `/etc/passwd` → root (earlier) |
| `overlayfs` | CVE-2021-3493 | Ubuntu 20.04.0 / 5.4.0-26 | userns + xattr copy-up, clean |
| `overlayfs_setuid` | CVE-2023-0386 | Ubuntu 22.04.0 / 5.15.0-25 | **after a full rewrite** — see below |
| `pwnkit` | CVE-2021-4034 | Ubuntu 20.04.0 / polkit 0.105-26ubuntu1 | **after a fix** — see below |
| `sudo_runas_neg1` | CVE-2019-14287 | Ubuntu 18.04.2 / sudo 1.8.21p2 + sudoers `(ALL,!root)` | `sudo -u#-1` → uid 0 |

## Fixed this session

- **`pwnkit`** — reported `EXPLOIT_OK` but did **not** root (glibc "Could not
  open converter … to PWNKIT"). Root cause: missing the `GCONV_PATH=.`
  re-injection directory + `chdir(workdir)`. Fixed → now lands real root on a
  vulnerable host. (commit `24b839e`)
- **`ptrace_traceme`** — reported `EXPLOIT_OK` but did **not** root; the bundled
  ptrace sequence is a non-working placeholder (it `PTRACE_ATTACH`es to the
  tracer, which by then has reparented to init → `EPERM`). Made **honest**
  (verifies `euid==0`, otherwise `EXPLOIT_FAIL`); a faithful CVE-2019-13272 port
  (Jann Horn / bcoles: `PTRACE_TRACEME` + setuid execve + registered polkit
  agent) is still required to land root. (commit `59cc2be`)
- **`overlayfs_setuid`** (CVE-2023-0386) — **rewritten and now lands real root**
  (uid=0 witnessed out-of-band on Ubuntu 22.04.0 / 5.15.0-25). The shipped
  module used a bogus `chown`-the-merged-view technique that never worked. The
  real bug needs a **FUSE lower layer** exporting a setuid-root file; overlay
  copy-up then materialises it in the real upper as a genuine setuid-root
  binary. Key findings from the port (all four were required):
    1. Overlay refuses a **userns-mounted** FUSE lowerdir (ENOSYS) — FUSE must
       be mounted in the **init ns** via the setuid `fusermount` helper (libfuse
       does this). A raw `/dev/fuse` server was tried and abandoned: its INIT
       handshake needs `poll()` on the non-blocking fd, and a malformed reply
       destabilised the kernel — fragile and inappropriate. libfuse is linked
       conditionally (pkg-config `fuse`/`fuse3`), matching `pack2theroot`.
    2. **fuse2** low-level API (`fuse_mount`/`fuse_new`/`fuse_loop_mt`, empty
       args) — `fuse_main` advertises splice/copy_file_range caps that make the
       kernel attempt `copy_file_range` at copy-up → ENOSYS with no fallback.
    3. **`read_buf`** callback (copy-up's splice read path).
    4. **`ioctl`** callback — copy-up issues `FS_IOC_GETFLAGS` on the lower; a
       server without an ioctl handler returns ENOSYS and copy-up fails. This
       was the last missing piece.
  Debugging was isolated by driving the exploit orchestration against the public
  PoC's `./fuse`, then swapping servers, then comparing `fops`.
- **`cgroup_release_agent`** — two real bugs fixed (commit `8c45b2b`): it read
  `getuid()` **after** `unshare(CLONE_NEWUSER)` (→ `65534`, so `uid_map` write
  was `"0 65534 1"` → EPERM), and it omitted `CLONE_NEWCGROUP` (→ cgroup-v1
  mount EPERM). Now the userns+cgroupns+mount setup is correct. It still can't
  root a **bare** unprivileged user on a stock systemd host: every v1 controller
  is pre-mounted (its `release_agent` is init-owned → EACCES from the userns)
  and a fresh named hierarchy is refused. Reachable in a **container** context
  (CAP_SYS_ADMIN / an ownable cgroup) — matches its "host root from rootless
  container" framing. The `getuid()`-after-`unshare` bug is a pattern to grep
  for across the other userns modules.

## Needs a faithful PoC port (genuinely vulnerable target, exploit doesn't land)

| module | CVE | target tested | what's wrong |
|---|---|---|---|
| `ptrace_traceme` | CVE-2019-13272 | Ubuntu 18.04.2 / 4.15.0-50 | placeholder technique (now honest); needs the real cred-transfer PoC (polkit agent) — substantial port |
| `overlayfs_setuid` | CVE-2023-0386 | Ubuntu 22.04.0 / 5.15.0-25.25 | **Kernel confirmed vulnerable empirically** — the upstream PoC (xkaneiki, libfuse) pops root here (`uid=0(root)`, root-owned witness). The working technique: mount a FUSE fs exporting `/file` (st_uid=0, mode 04777) in the **init ns** via the setuid `fusermount3` helper, then overlay-in-userns with that FUSE lowerdir + copy-up. My module's non-FUSE `chown` variant yields `upper/file` uid=1000 (no escalation); mounting FUSE **inside** the userns → overlay `ENOSYS`. Attempted a self-contained **raw `/dev/fuse`** port: got the `fusermount` fd-passing handshake (`SCM_RIGHTS`) + mount working, but the server hits `EINVAL` on `read()` after `FUSE_INIT` (non-blocking fd → needs `poll()`), and even with poll/buffer fixes the raw server serving was flaky and repeatedly **wedged/rebooted the VM** — i.e. the raw protocol reimplementation is fragile and can destabilise the target, which is *worse* for the corpus than a lib dependency. **Conclusion: use libfuse** (proven, robust; matches the `pack2theroot` conditional-lib precedent). Port is scoped and ready; needs a clean session to implement + verify. |
| `sudoedit_editor` | CVE-2023-22809 | Ubuntu 22.04.0 / sudo 1.9.9 | vulnerable sudo version + sudoers `sudoedit` grant present; module returns `EXPLOIT_FAIL` — the `SUDO_EDITOR`/`--` arg-injection reaches sudoedit's writable-dir guard. Needs a target-file whose dir the injection can satisfy (e.g. `/etc/passwd`), and module debugging. Structural, tractable next. |
| `sudo_samedit` | CVE-2021-3156 | Ubuntu 18.04.2 + 20.04.0 | honest `EXPLOIT_FAIL`; Baron Samedit is heap/libc-version-specific, needs a per-target tuned PoC. Hardest. |

## Inconclusive (detect version-blind vs vendor backport)

| module | CVE | note |
|---|---|---|
| `dirty_pipe` | CVE-2022-0847 | Ubuntu 22.04.0's 5.15.0-25.25 almost certainly carries the backported fix (USN-5317); `detect()` is version-only so says VULNERABLE. Needs a genuinely pre-fix kernel (e.g. 5.13.0-19, or mainline 5.16.10) to verify the exploit. |

## Not yet exploit-tested (the bulk — ~30 modules)

- **🟡 kernel primitives** (`nf_tables`, `nft_set_uaf`, `nft_payload`,
  `nft_fwd_dup`, `netfilter_xtcompat`, `af_packet`, `af_packet2`, `af_unix_gc`,
  `cls_route4`, `fuse_legacy`, `stackrot`, `sequoia`, `nft_pipapo`, `vsock_uaf`,
  `pintheft`): return `EXPLOIT_FAIL` by design; landing root needs a per-kernel
  `--dump-offsets` + `--full-chain` (modprobe_path finisher) pass on a vulnerable
  kernel.
- **Structural userspace** (`sudoedit_editor`, `sudo_chwoot`, `sudo_host`):
  need specific sudo versions + sudoers config; likely tractable.
- **2026 CVEs** (`copy_fail` ×5, `dirtydecrypt`, `fragnesia`, `cifswitch`,
  `nft_catchall`, `ptrace_pidfd`): need vulnerable 2026 kernels; the reconstructed
  race triggers (`bad_epoll`, `ghostlock`, `nft_catchall`) are deliberately
  under-driven and won't pop root by design.
- **Environment-blocked**: `vmwgfx` (VMware guest only), `dirty_cow` (needs ≤4.4),
  `mutagen_astronomy` (CentOS 6 / Debian 7).
- **D-Bus/desktop** (`pack2theroot`, `udisks_libblockdev`): need the polkit/D-Bus
  stack + a provisioner rule.

## Method notes for continuation

- Frozen images: `cloud-images-archive.ubuntu.com/releases/<name>/release-<date>/`
  are unpatched and vulnerable-by-default for CVEs disclosed after that date — far
  easier than downgrading packages on current images.
- gcc must be present *in* the VM (several exploits compile payloads at runtime);
  on EOL LTS, point apt at the archive main pocket.
- **Always verify root out of band.** The module self-report is not trustworthy
  (two flagships lied). `witness.sh` is the reference check.