SKELETONKEY/README.md

SKELETONKEY

One curated binary. 44 Linux LPE modules covering 39 CVEs from 2016 → 2026. Every year 2016 → 2026 covered. 28 confirmed end-to-end against real Linux VMs via tools/verify-vm/. 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 \
  && export PATH="$HOME/.local/bin:$PATH" \
  && 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 nothing
• auto-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 (schema).
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

44 modules covering 39 distinct CVEs across the 2016 → 2026 LPE timeline. 28 of the 39 CVEs have been empirically verified in real Linux VMs via tools/verify-vm/; the 11 still-pending entries are blocked by their target environment (legacy hypervisor, EOL kernel, or the t64-transition libc rollout) or are brand-new additions awaiting a VM sweep, not by missing code.

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).

🟢 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

Empirical verification (28 of 39 CVEs)

Records in docs/VERIFICATIONS.jsonl prove each verdict against a known-target VM. Coverage:

Distro / kernel	Modules verified
Ubuntu 18.04 (4.15.0, sudo 1.8.21p2)	af_packet · ptrace_traceme · sudo_samedit · sudo_runas_neg1
Ubuntu 20.04 (5.4.0-26 pinned + 5.15 HWE)	af_packet2 · cls_route4 · nft_payload · overlayfs · pwnkit · sequoia · tioscpgrp
Ubuntu 22.04 (5.15 stock + mainline 5.15.5 / 6.1.10 / 6.19.7)	af_unix_gc · dirty_pipe · dirtydecrypt · entrybleed · nf_tables · nft_set_uaf · nft_pipapo · overlayfs_setuid · stackrot · sudoedit_editor · sudo_chwoot
Debian 11 (5.10 stock)	cgroup_release_agent · fuse_legacy · netfilter_xtcompat · nft_fwd_dup
Debian 12 (6.1 stock + udisks2 / polkit allow rule)	pack2theroot · udisks_libblockdev

Not yet verified (11): vmwgfx (VMware-guest-only — no public Vagrant box), dirty_cow (needs ≤ 4.4 kernel — older than every supported box), mutagen_astronomy (mainline 4.14.70 kernel-panics on Ubuntu 18.04 rootfs — needs CentOS 6 / Debian 7), pintheft & vsock_uaf (kernel modules not loaded on common Vagrant boxes), fragnesia (mainline 7.0.5 kernel .debs depend on the t64-transition libs from Ubuntu 24.04+/Debian 13+; no Parallels-supported box has those yet), ptrace_pidfd (brand-new 2026-05 Qualys disclosure — added this cycle, VM sweep pending), sudo_host (brand-new 2025-06 Stratascale disclosure — added this cycle, VM sweep pending), cifswitch (detect + add_key primitive VM-verified; full chain

• patched-kernel discriminator pending), nft_catchall (reconstructed kernel-UAF trigger, not VM-verified), bad_epoll (reconstructed epoll race trigger — deliberately under-driven, not VM-verified). All eleven are flagged in tools/verify-vm/targets.yaml with rationale.

See CVES.md for per-module CVE, kernel range, and detection status. Run skeletonkey --module-info <name> for the embedded verification records per module.

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

# One-page operator briefing for a single CVE: CWE / MITRE ATT&CK /
# CISA KEV status, live detect() trace, OPSEC footprint, detection
# coverage. Useful for triage tickets and SOC analyst handoffs.
skeletonkey --explain nf_tables

# 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 44 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:

• --scan walks every module's detect() against the running host
• --exploit <name> --i-know runs the named module's exploit (the --i-know flag is the authorization gate)
• --auto --i-know does 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-offsets reads /proc/kallsyms + /boot/System.map and emits a ready-to-paste C entry for the --full-chain offset 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

v0.9.12 cut 2026-07-04. 44 modules across 39 CVEs — every year 2016 → 2026 now covered. Newest: bad_epoll (CVE-2026-46242, Jaeyoung Chung's "Bad Epoll" — a race use-after-free in fs/eventpoll.c where ep_remove() clears file->f_ep under f_lock but keeps using the file while a concurrent __fput() frees the still-referenced struct eventpoll; reachable by any unprivileged user with no user namespace, weaponised via cross-cache + /proc/self/fdinfo arb-read; kernelCTF public PoC — shipped as a deliberately under-driven, reconstructed reachability trigger with the corpus's lowest --auto safety rank), nft_catchall (CVE-2026-23111, the nf_tables nft_map_catchall_activate abort-path UAF — an inverted condition frees a chain still referenced by a catch-all GOTO map element; public reproduction by FuzzingLabs), cifswitch (CVE-2026-46243, Asim Manizada's "CIFSwitch" — the cifs.spnego key type trusts userspace-forged authority fields, coercing the root cifs.upcall helper into loading an attacker NSS module as root), and ptrace_pidfd (CVE-2026-46333, Qualys's __ptrace_may_access / pidfd_getfd credential-steal). v0.9.0 added 5 gap-fillers (mutagen_astronomy / sudo_runas_neg1 / tioscpgrp / vsock_uaf / nft_pipapo); v0.8.0 added 3 (sudo_chwoot / udisks_libblockdev / pintheft). v0.9.1 and v0.9.2 are verification-only sweeps that took the verified count from 22 → 28 by booting real vulnerable kernels (Ubuntu mainline 5.4.0-26, 5.15.5, 6.19.7 + provisioner-built sudo 1.9.16p1 + Debian 12 + polkit allow rule for udisks). 28 empirically verified against real Linux VMs (Ubuntu 18.04 / 20.04 / 22.04 + Debian 11 / 12 + mainline kernels from kernel.ubuntu.com). 88-test unit harness + ASan/UBSan + clang-tidy on every push. 4 prebuilt binaries (x86_64 + arm64, each in dynamic + static-musl flavors).

Reliability + accuracy work in v0.7.x:

• Shared host fingerprint (core/host.{h,c}) populated once at startup — kernel/distro/userns gates/sudo+polkit versions — exposed to every module via ctx->host.
• Test harness (tests/, make test) — 88 tests: 33 kernel_range unit tests + 55 detect() integration tests over mocked host fingerprints. Runs in CI on every push.
• VM verifier (tools/verify-vm/) — Vagrant + Parallels scaffold that boots known-vulnerable kernels (stock distro + mainline via kernel.ubuntu.com), runs --explain --active per module, records match/MISMATCH/PRECOND_FAIL as JSON. 28 modules confirmed end-to-end.
• --explain <module> — single-page operator briefing: CVE / CWE / MITRE ATT&CK / CISA KEV status, host fingerprint, live detect() trace, OPSEC footprint, detection-rule coverage, verified-on records. Paste-into-ticket ready.
• CVE metadata pipeline (tools/refresh-cve-metadata.py) — fetches CISA KEV catalog + NVD CWE; 13 of 39 modules cover KEV-listed CVEs.
• 151 detection rules across auditd / sigma / yara / falco; one command exports the corpus to your SIEM.
• --auto upgrades: per-detect 15s timeout, fork-isolated detect + exploit, structured verdict table, scan summary, --dry-run.

Not yet verified (11 of 39 CVEs): vmwgfx (VMware-guest only), dirty_cow (needs ≤ 4.4 kernel), mutagen_astronomy (mainline 4.14.70 panics on Ubuntu 18.04 rootfs — needs CentOS 6 / Debian 7), pintheft + vsock_uaf (kernel modules not autoloaded on common Vagrant boxes), fragnesia (mainline 7.0.5 .debs need t64-transition libs from Ubuntu 24.04+ / Debian 13+), ptrace_pidfd + sudo_host

• cifswitch (cifswitch detect + primitive VM-verified; full chain pending) + nft_catchall (reconstructed kernel-UAF trigger, not VM-verified) + bad_epoll (reconstructed epoll race trigger, deliberately under-driven, not VM-verified). Rationale in tools/verify-vm/targets.yaml.

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.

Keeping kernel_range tables current. tools/refresh-kernel-ranges.py polls Debian's security tracker and reports drift between each module's hardcoded kernel_patched_from thresholds and the fixed-versions Debian actually ships. Run periodically (or in CI) to catch new backports that need to land in the corpus:

tools/refresh-kernel-ranges.py            # human report
tools/refresh-kernel-ranges.py --json     # machine-readable
tools/refresh-kernel-ranges.py --patch    # proposed C-source edits

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.