Files
SKELETONKEY/skeletonkey.c
T
leviathan d84b3b0033 release v0.9.0: 5 gap-fillers — every year 2016 → 2026 now covered
Five new modules close the 2018 gap entirely and thicken
2019 / 2020 / 2024. All five carry the full 4-format detection-rule
corpus + opsec_notes + arch_support + register helpers.

CVE-2018-14634 — mutagen_astronomy (Qualys, closes 2018)
  create_elf_tables() int wrap → SUID-execve stack corruption.
  CISA KEV-listed Jan 2026 despite the bug's age; legacy RHEL 7 /
  CentOS 7 / Debian 8 fleets still affected. 🟡 PRIMITIVE.
  arch_support: x86_64+unverified-arm64.

CVE-2019-14287 — sudo_runas_neg1 (Joe Vennix)
  sudo -u#-1 → uid_t underflow → root despite (ALL,!root) blacklist.
  Pure userspace logic bug; the famous Apple Information Security
  finding. detect() looks for a (ALL,!root) grant in sudo -ln output;
  PRECOND_FAIL when no such grant exists for the invoking user.
  arch_support: any (4 -> 5 userspace 'any' modules).

CVE-2020-29661 — tioscpgrp (Jann Horn / Project Zero)
  TTY TIOCSPGRP ioctl race on PTY pairs → struct pid UAF in
  kmalloc-256. Affects everything through Linux 5.9.13. 🟡 PRIMITIVE
  (race-driver + msg_msg groom). Public PoCs from grsecurity /
  spender + Maxime Peterlin.

CVE-2024-50264 — vsock_uaf (a13xp0p0v / Pwnie Award 2025 winner)
  AF_VSOCK connect-race UAF in kmalloc-96. Pwn2Own 2024 + Pwnie
  2025 winner. Reachable as plain unprivileged user (no userns
  required — unusual). Two public exploit paths: @v4bel+@qwerty
  kernelCTF (BPF JIT spray + SLUBStick) and Alexander Popov / PT
  SWARM (msg_msg). 🟡 PRIMITIVE.

CVE-2024-26581 — nft_pipapo (Notselwyn II, 'Flipping Pages')
  nft_set_pipapo destroy-race UAF. Sibling to nf_tables
  (CVE-2024-1086) from the same Notselwyn paper. Distinct bug in
  the pipapo set substrate. Same family signature. 🟡 PRIMITIVE.

Plumbing changes:

  core/registry.h + registry_all.c — 5 new register declarations
    + calls.
  Makefile — 5 new MUT/SRN/TIO/VSK/PIP module groups in MODULE_OBJS.
  tests/test_detect.c — 7 new test rows covering the new modules
    (above-fix OK, predates-the-bug OK, sudo-no-grant PRECOND_FAIL).
  tools/verify-vm/targets.yaml — verifier entries for all 5 with
    honest 'expect_detect' values based on what Vagrant boxes can
    realistically reach (mutagen_astronomy gets OK on stock 18.04
    since 4.15.0-213 is post-fix; sudo_runas_neg1 gets PRECOND_FAIL
    because no (ALL,!root) grant on default vagrant user; tioscpgrp
    + nft_pipapo VULNERABLE with kernel pins; vsock_uaf flagged
    manual because vsock module rarely available on CI runners).
  tools/refresh-cve-metadata.py — added curl fallback for the CISA
    KEV CSV fetch (urlopen times out intermittently against CISA's
    HTTP/2 endpoint).

Corpus growth across v0.8.0 + v0.9.0:

                v0.7.1    v0.8.0    v0.9.0
  Modules          31        34        39
  Distinct CVEs    26        29        34
  KEV-listed       10        10        11 (mutagen_astronomy)
  arch 'any'        4         6         7 (sudo_runas_neg1)
  Years 2016-2026:  10/11     10/11     **11/11**

Year-by-year coverage:

  2016: 1   2017: 1   2018: 1   2019: 2   2020: 2
  2021: 5   2022: 5   2023: 8   2024: 3   2025: 2   2026: 4

CVE-2018 gap → CLOSED. Every year from 2016 through 2026 now has
at least one module.

Surfaces updated:
  - README.md: badge → 22 VM-verified / 34, Status section refreshed
  - docs/index.html: hero eyebrow + footer → v0.9.0, hero tagline
    'every year 2016 → 2026', stats chips → 39 / 22 / 11 / 151
  - docs/RELEASE_NOTES.md: v0.9.0 entry added on top with year
    coverage matrix + per-module breakdown; v0.8.0 + v0.7.1 entries
    preserved below
  - docs/og.svg + og.png: regenerated with new numbers + 'Every
    year 2016 → 2026' tagline

CVE metadata refresh (tools/refresh-cve-metadata.py) deferred to
follow-up — CISA KEV CSV + NVD CVE API were timing out during the
v0.9.0 push window. The 5 new CVEs will return NULL from
cve_metadata_lookup() until the refresh runs (—module-info simply
skips the WEAKNESS/THREAT INTEL header for them; no functional
impact). Re-run 'tools/refresh-cve-metadata.py' when network
cooperates.

Tests: macOS local 33/33 kernel_range pass; detect-test stubs (88
total) build clean; ASan/UBSan + clang-tidy CI jobs still green
from the v0.7.x setup.
2026-05-23 22:15:44 -04:00

1488 lines
61 KiB
C

/*
* SKELETONKEY — top-level dispatcher
*
* Usage:
* skeletonkey --scan # run every module's detect()
* skeletonkey --scan --json # machine-readable output
* skeletonkey --scan --active # invasive probes (still no /etc/passwd writes)
* skeletonkey --list # list registered modules
* skeletonkey --exploit <name> --i-know # run a named module's exploit
* skeletonkey --mitigate <name> # apply a temporary mitigation
* skeletonkey --cleanup <name> # undo --exploit or --mitigate side effects
*
* Phase 1 scope: thin dispatcher over the copy_fail_family bridge.
* Future phases add: --detect-rules export, multi-family registry,
* fingerprint pre-pass, etc.
*/
#include "core/module.h"
#include "core/registry.h"
#include "core/offsets.h"
#include "core/host.h"
#include "core/cve_metadata.h"
#include "core/verifications.h"
#include <time.h>
#include <sys/utsname.h>
#include <sys/wait.h>
#include <signal.h>
#include <fcntl.h>
#include <getopt.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define SKELETONKEY_VERSION "0.9.0"
static const char BANNER[] =
"\n"
"SKELETONKEY — Curated Linux kernel LPE corpus — v" SKELETONKEY_VERSION "\n"
"AUTHORIZED TESTING ONLY — see docs/ETHICS.md\n"
"\n";
static void usage(const char *prog)
{
fprintf(stderr,
"Usage: %s [MODE] [OPTIONS]\n"
"\n"
"Modes (default: --scan):\n"
" --scan run every module's detect() across the host\n"
" --list list registered modules and exit\n"
" --exploit <name> run named module's exploit (REQUIRES --i-know)\n"
" --mitigate <name> apply named module's mitigation\n"
" --cleanup <name> undo named module's exploit/mitigate side effects\n"
" --detect-rules dump detection rules for every module\n"
" (combine with --format=auditd|sigma|yara|falco)\n"
" --module-info <name> full metadata + rule bodies for one module\n"
" (combine with --json for machine-readable output)\n"
" --explain <name> one-page operator briefing: CVE / CWE / ATT&CK /\n"
" KEV, host fingerprint, live detect() trace + verdict,\n"
" OPSEC footprint, detection coverage, mitigation.\n"
" Useful for triage tickets and SOC analyst handoffs.\n"
" --auto scan host, rank vulnerable modules by safety, run the\n"
" safest exploit. Requires --i-know. The 'one command\n"
" that gets you root' mode — picks structural exploits\n"
" (no kernel state touched) over page-cache writes over\n"
" kernel primitives over races.\n"
" --audit system-hygiene scan: setuid binaries, world-writable\n"
" files in /etc, file capabilities, sudo NOPASSWD\n"
" (complements --scan; answers 'is this box\n"
" generally privesc-exposed?')\n"
" --dump-offsets walk /proc/kallsyms + /boot/System.map and emit a\n"
" C struct-entry ready to paste into core/offsets.c's\n"
" kernel_table[] for the --full-chain finisher.\n"
" Needs root (or kernel.kptr_restrict=0) to read\n"
" kallsyms. See docs/OFFSETS.md.\n"
" --version print version\n"
" --help this message\n"
"\n"
"Options:\n"
" --i-know authorization gate for --exploit modes\n"
" --active in --scan, do invasive sentinel probes (no /etc/passwd writes)\n"
" --no-shell in --exploit modes, prepare but don't drop to shell\n"
" --dry-run preview only — do the scan + pick, never call exploit/\n"
" mitigate/cleanup. Useful with --auto to see what would\n"
" fire before authorizing it.\n"
" --full-chain in --exploit modes, attempt full root-pop after primitive\n"
" (the 🟡 modules return primitive-only by default; with\n"
" --full-chain they continue to leak → arb-write →\n"
" modprobe_path overwrite. Requires resolvable kernel\n"
" offsets — env vars, /proc/kallsyms, or /boot/System.map.\n"
" See docs/OFFSETS.md.)\n"
" --json machine-readable output (for SIEM/CI)\n"
" --no-color disable ANSI color codes\n"
" --format <f> with --detect-rules: auditd (default), sigma, yara, falco\n"
"\n"
"Exit codes:\n"
" 0 not vulnerable / OK 2 vulnerable 5 exploit succeeded\n"
" 1 test error 3 exploit failed 4 preconditions missing\n",
prog);
}
enum mode {
MODE_SCAN,
MODE_LIST,
MODE_EXPLOIT,
MODE_MITIGATE,
MODE_CLEANUP,
MODE_DETECT_RULES,
MODE_MODULE_INFO,
MODE_AUDIT,
MODE_AUTO,
MODE_DUMP_OFFSETS,
MODE_HELP,
MODE_VERSION,
MODE_EXPLAIN,
};
enum detect_format {
FMT_AUDITD,
FMT_SIGMA,
FMT_YARA,
FMT_FALCO,
};
static const char *result_str(skeletonkey_result_t r)
{
switch (r) {
case SKELETONKEY_OK: return "OK";
case SKELETONKEY_TEST_ERROR: return "ERROR";
case SKELETONKEY_VULNERABLE: return "VULNERABLE";
case SKELETONKEY_EXPLOIT_FAIL: return "EXPLOIT_FAIL";
case SKELETONKEY_PRECOND_FAIL: return "PRECOND_FAIL";
case SKELETONKEY_EXPLOIT_OK: return "EXPLOIT_OK";
}
return "?";
}
/* JSON-escape a string for inclusion in stdout output. Quick + safe:
* escapes \" and \\ and newlines; passes through ASCII printable.
* Caller must call json_escape_done() to free the result. */
static char *json_escape(const char *s)
{
if (s == NULL) return NULL;
size_t n = strlen(s);
char *out = malloc(n * 2 + 1); /* worst case: every char doubles */
if (!out) return NULL;
char *p = out;
for (size_t i = 0; i < n; i++) {
unsigned char c = (unsigned char)s[i];
if (c == '"' || c == '\\') { *p++ = '\\'; *p++ = c; }
else if (c == '\n') { *p++ = '\\'; *p++ = 'n'; }
else if (c == '\r') { *p++ = '\\'; *p++ = 'r'; }
else if (c == '\t') { *p++ = '\\'; *p++ = 't'; }
else if (c < 0x20) { /* skip — should be rare in our strings */ }
else *p++ = c;
}
*p = 0;
return out;
}
static void emit_module_json(const struct skeletonkey_module *m, bool include_rules)
{
char *name = json_escape(m->name);
char *cve = json_escape(m->cve);
char *summary = json_escape(m->summary);
char *family = json_escape(m->family);
char *krange = json_escape(m->kernel_range);
fprintf(stdout,
"{\"name\":\"%s\",\"cve\":\"%s\",\"family\":\"%s\","
"\"kernel_range\":\"%s\",\"summary\":\"%s\","
"\"has\":{\"detect\":%s,\"exploit\":%s,\"mitigate\":%s,\"cleanup\":%s,"
"\"auditd\":%s,\"sigma\":%s,\"yara\":%s,\"falco\":%s}",
name ? name : "",
cve ? cve : "",
family ? family : "",
krange ? krange : "",
summary ? summary : "",
m->detect ? "true" : "false",
m->exploit ? "true" : "false",
m->mitigate ? "true" : "false",
m->cleanup ? "true" : "false",
m->detect_auditd ? "true" : "false",
m->detect_sigma ? "true" : "false",
m->detect_yara ? "true" : "false",
m->detect_falco ? "true" : "false");
/* CVE-keyed triage metadata (CWE, ATT&CK, KEV). Sourced from CISA
* + NVD via tools/refresh-cve-metadata.py; lookup is O(corpus). */
const struct cve_metadata *md = cve_metadata_lookup(m->cve);
if (md) {
char *cwe = json_escape(md->cwe);
char *tech = json_escape(md->attack_technique);
char *sub = json_escape(md->attack_subtechnique);
char *kdate = json_escape(md->kev_date_added);
fprintf(stdout,
",\"triage\":{\"cwe\":%s%s%s,"
"\"attack_technique\":%s%s%s,"
"\"attack_subtechnique\":%s%s%s,"
"\"in_kev\":%s,"
"\"kev_date_added\":\"%s\"}",
cwe ? "\"" : "", cwe ? cwe : "null", cwe ? "\"" : "",
tech ? "\"" : "", tech ? tech : "null", tech ? "\"" : "",
sub ? "\"" : "", sub ? sub : "null", sub ? "\"" : "",
md->in_kev ? "true" : "false",
kdate ? kdate : "");
free(cwe); free(tech); free(sub); free(kdate);
}
/* Per-module OPSEC notes — telemetry footprint of this exploit. */
if (m->opsec_notes) {
char *op = json_escape(m->opsec_notes);
fprintf(stdout, ",\"opsec_notes\":\"%s\"", op ? op : "");
free(op);
}
/* Architecture support for the exploit body. */
if (m->arch_support) {
char *a = json_escape(m->arch_support);
fprintf(stdout, ",\"arch_support\":\"%s\"", a ? a : "");
free(a);
}
/* Empirical verification records: (distro, kernel, date) tuples
* where the module's detect() was confirmed against a real target. */
size_t nv = 0;
const struct verification_record *vrs = verifications_for_module(m->name, &nv);
if (nv > 0) {
fprintf(stdout, ",\"verified_on\":[");
for (size_t i = 0; i < nv; i++) {
char *vat = json_escape(vrs[i].verified_at);
char *vkr = json_escape(vrs[i].host_kernel);
char *vds = json_escape(vrs[i].host_distro);
char *vbx = json_escape(vrs[i].vm_box);
char *vst = json_escape(vrs[i].status);
char *vac = json_escape(vrs[i].actual_detect);
fprintf(stdout,
"%s{\"verified_at\":\"%s\",\"host_kernel\":\"%s\","
"\"host_distro\":\"%s\",\"vm_box\":\"%s\","
"\"actual_detect\":\"%s\",\"status\":\"%s\"}",
i ? "," : "",
vat ? vat : "", vkr ? vkr : "", vds ? vds : "",
vbx ? vbx : "", vac ? vac : "", vst ? vst : "");
free(vat); free(vkr); free(vds); free(vbx); free(vst); free(vac);
}
fprintf(stdout, "]");
}
if (include_rules) {
/* Embed the actual rule text. Useful for --module-info. */
char *aud = json_escape(m->detect_auditd);
char *sig = json_escape(m->detect_sigma);
char *yar = json_escape(m->detect_yara);
char *fal = json_escape(m->detect_falco);
fprintf(stdout,
",\"detect_rules\":{\"auditd\":%s%s%s,\"sigma\":%s%s%s,"
"\"yara\":%s%s%s,\"falco\":%s%s%s}",
aud ? "\"" : "", aud ? aud : "null", aud ? "\"" : "",
sig ? "\"" : "", sig ? sig : "null", sig ? "\"" : "",
yar ? "\"" : "", yar ? yar : "null", yar ? "\"" : "",
fal ? "\"" : "", fal ? fal : "null", fal ? "\"" : "");
free(aud); free(sig); free(yar); free(fal);
}
fprintf(stdout, "}");
free(name); free(cve); free(summary); free(family); free(krange);
}
static int cmd_list(const struct skeletonkey_ctx *ctx)
{
size_t n = skeletonkey_module_count();
if (ctx->json) {
fprintf(stdout, "{\"version\":\"%s\",\"modules\":[", SKELETONKEY_VERSION);
for (size_t i = 0; i < n; i++) {
if (i) fputc(',', stdout);
emit_module_json(skeletonkey_module_at(i), false);
}
fprintf(stdout, "]}\n");
return 0;
}
/* The ARCH column shows where exploit() is known/expected to work:
* "any" → userspace or arch-agnostic kernel primitive
* "x64" → x86_64 only (entrybleed)
* "x64?" → x86_64 verified, arm64 untested (the honest default
* for kernel modules that haven't been arm64-confirmed) */
fprintf(stdout, "%-20s %-18s %-3s %-3s %-5s %-25s %s\n",
"NAME", "CVE", "KEV", "VFY", "ARCH", "FAMILY", "SUMMARY");
fprintf(stdout, "%-20s %-18s %-3s %-3s %-5s %-25s %s\n",
"----", "---", "---", "---", "----", "------", "-------");
size_t n_kev = 0, n_vfy = 0, n_any = 0;
for (size_t i = 0; i < n; i++) {
const struct skeletonkey_module *m = skeletonkey_module_at(i);
const struct cve_metadata *md = cve_metadata_lookup(m->cve);
bool in_kev = md && md->in_kev;
bool verified = verifications_module_has_match(m->name);
const char *arch_abbr = "?";
if (m->arch_support) {
if (strcmp(m->arch_support, "any") == 0) { arch_abbr = "any"; n_any++; }
else if (strcmp(m->arch_support, "x86_64") == 0) { arch_abbr = "x64"; }
else { arch_abbr = "x64?"; }
}
if (in_kev) n_kev++;
if (verified) n_vfy++;
fprintf(stdout, "%-20s %-18s %-3s %-3s %-5s %-25s %s\n",
m->name, m->cve,
in_kev ? "" : "",
verified ? "" : "",
arch_abbr,
m->family, m->summary);
}
fprintf(stdout, "\n%zu modules registered · %zu in CISA KEV (★) · "
"%zu empirically verified in real VMs (✓) · "
"%zu arch-independent (any)\n",
n, n_kev, n_vfy, n_any);
fprintf(stdout, "ARCH key: 'any' = userspace or arch-agnostic; "
"'x64' = x86_64 only; 'x64?' = x86_64 verified, "
"arm64 untested\n");
return 0;
}
/* --audit: system-hygiene scan beyond per-CVE detect. Inventories
* setuid binaries, world-writable system files, capability-bound
* non-standard binaries, NOPASSWD sudo entries. Complements --scan;
* answers "is this box generally exposed to privesc?" beyond
* "does it have any of the known kernel CVEs?".
*
* Output is structured findings. --json switches to a single JSON
* object with arrays per category. Side-effect-free: read-only
* filesystem walks. */
struct finding {
const char *category; /* "setuid", "world_writable", "capability", "sudo" */
char path[512];
char note[256];
};
static void print_finding_human(const struct finding *f)
{
fprintf(stdout, "[%-15s] %-50s %s\n",
f->category, f->path, f->note);
}
/* Walk one filesystem path looking for setuid-root binaries. Bounded
* via find(1) for portability (every distro ships find). */
static int audit_setuid(int *count_out, bool json,
bool *first_json_emitted)
{
/* Use popen() on `find` rather than recursive opendir() — much
* simpler, every distro ships find. Limit to common
* binary-bearing dirs to keep runtime reasonable. */
static const char *cmd =
"find /usr/bin /usr/sbin /bin /sbin /usr/local/bin /usr/local/sbin "
"-xdev -perm -4000 -type f 2>/dev/null";
FILE *p = popen(cmd, "r");
if (!p) return -1;
char line[1024];
int n = 0;
/* Set of suspicious binaries — these are notable in the LPE world.
* The full setuid inventory is informational; this list flags
* specific items as "review this". */
static const struct { const char *path; const char *note; } SUSP[] = {
{"/usr/bin/pkexec", "Pwnkit CVE-2021-4034 history; tightly audit polkit policy"},
{"/usr/bin/mount.cifs", "historically setuid-root; check distro hardening"},
{"/usr/bin/fusermount3", "historically setuid; userns-related LPE history"},
{"/usr/bin/passwd", "expected setuid; verify integrity"},
{"/usr/bin/sudo", "expected setuid; verify integrity + sudoers"},
{"/usr/bin/su", "expected setuid; verify integrity"},
{"/usr/lib/snapd/snap-confine", "Ubuntu snap sandbox-escape history"},
{NULL, NULL},
};
while (fgets(line, sizeof line, p)) {
size_t L = strlen(line);
while (L && (line[L-1] == '\n' || line[L-1] == '\r')) line[--L] = 0;
const char *note = "setuid binary — review";
for (size_t i = 0; SUSP[i].path; i++) {
if (strcmp(line, SUSP[i].path) == 0) { note = SUSP[i].note; break; }
}
if (json) {
char *p_esc = json_escape(line);
char *n_esc = json_escape(note);
fprintf(stdout, "%s{\"category\":\"setuid\",\"path\":\"%s\",\"note\":\"%s\"}",
*first_json_emitted ? "," : "",
p_esc ? p_esc : "", n_esc ? n_esc : "");
*first_json_emitted = true;
free(p_esc); free(n_esc);
} else {
struct finding f = { .category = "setuid" };
snprintf(f.path, sizeof f.path, "%s", line);
snprintf(f.note, sizeof f.note, "%s", note);
print_finding_human(&f);
}
n++;
}
pclose(p);
if (count_out) *count_out = n;
return 0;
}
/* Look for world-writable files inside /etc. Catches obviously-broken
* filesystem permissions where any user can edit system config. */
static int audit_world_writable(int *count_out, bool json,
bool *first_json_emitted)
{
static const char *cmd =
"find /etc -xdev -perm -0002 -type f 2>/dev/null";
FILE *p = popen(cmd, "r");
if (!p) return -1;
char line[1024];
int n = 0;
while (fgets(line, sizeof line, p)) {
size_t L = strlen(line);
while (L && (line[L-1] == '\n' || line[L-1] == '\r')) line[--L] = 0;
const char *note = "world-writable in /etc — anyone can edit";
if (json) {
char *p_esc = json_escape(line);
fprintf(stdout, "%s{\"category\":\"world_writable\",\"path\":\"%s\",\"note\":\"%s\"}",
*first_json_emitted ? "," : "", p_esc ? p_esc : "", note);
*first_json_emitted = true;
free(p_esc);
} else {
struct finding f = { .category = "world_writable" };
snprintf(f.path, sizeof f.path, "%s", line);
snprintf(f.note, sizeof f.note, "%s", note);
print_finding_human(&f);
}
n++;
}
pclose(p);
if (count_out) *count_out = n;
return 0;
}
/* Find files with file capabilities set. cap_setuid+ep or
* cap_dac_override+ep on a non-standard binary = potential
* post-exploit persistence or a misconfigured capability grant. */
static int audit_capabilities(int *count_out, bool json,
bool *first_json_emitted)
{
/* getcap is in libcap2-bin / libcap-progs depending on distro;
* skip cleanly if absent. */
if (access("/sbin/getcap", X_OK) != 0
&& access("/usr/sbin/getcap", X_OK) != 0
&& access("/usr/bin/getcap", X_OK) != 0) {
if (!json) {
fprintf(stderr, "[i] audit: getcap not installed — skipping capability scan\n");
}
if (count_out) *count_out = 0;
return 0;
}
static const char *cmd =
"getcap -r /usr/bin /usr/sbin /bin /sbin /usr/local 2>/dev/null";
FILE *p = popen(cmd, "r");
if (!p) return -1;
char line[1024];
int n = 0;
while (fgets(line, sizeof line, p)) {
size_t L = strlen(line);
while (L && (line[L-1] == '\n' || line[L-1] == '\r')) line[--L] = 0;
const char *note = "file capability set — verify legitimacy";
if (strstr(line, "cap_setuid+ep") || strstr(line, "cap_setgid+ep")
|| strstr(line, "cap_dac_override+ep") || strstr(line, "cap_sys_admin+ep")) {
note = "high-power cap+ep — privesc-equivalent if attacker-writable";
}
if (json) {
char *p_esc = json_escape(line);
fprintf(stdout, "%s{\"category\":\"capability\",\"path\":\"%s\",\"note\":\"%s\"}",
*first_json_emitted ? "," : "", p_esc ? p_esc : "", note);
*first_json_emitted = true;
free(p_esc);
} else {
struct finding f = { .category = "capability" };
snprintf(f.path, sizeof f.path, "%s", line);
snprintf(f.note, sizeof f.note, "%s", note);
print_finding_human(&f);
}
n++;
}
pclose(p);
if (count_out) *count_out = n;
return 0;
}
/* Check /etc/sudoers and /etc/sudoers.d for NOPASSWD entries. Many
* setups have legit NOPASSWD for service accounts; flag and let
* operator review. */
static int audit_sudo_nopasswd(int *count_out, bool json,
bool *first_json_emitted)
{
static const char *cmd =
"grep -rIn -E '^[^#].*NOPASSWD' /etc/sudoers /etc/sudoers.d 2>/dev/null";
FILE *p = popen(cmd, "r");
if (!p) return -1;
char line[1024];
int n = 0;
while (fgets(line, sizeof line, p)) {
size_t L = strlen(line);
while (L && (line[L-1] == '\n' || line[L-1] == '\r')) line[--L] = 0;
const char *note = "sudo NOPASSWD entry — verify scope";
if (json) {
char *p_esc = json_escape(line);
fprintf(stdout, "%s{\"category\":\"sudo\",\"path\":\"%s\",\"note\":\"%s\"}",
*first_json_emitted ? "," : "", p_esc ? p_esc : "", note);
*first_json_emitted = true;
free(p_esc);
} else {
struct finding f = { .category = "sudo" };
snprintf(f.path, sizeof f.path, "%s", line);
snprintf(f.note, sizeof f.note, "%s", note);
print_finding_human(&f);
}
n++;
}
pclose(p);
if (count_out) *count_out = n;
return 0;
}
static int cmd_audit(const struct skeletonkey_ctx *ctx)
{
int n_setuid = 0, n_ww = 0, n_cap = 0, n_sudo = 0;
if (ctx->json) {
fprintf(stdout, "{\"version\":\"%s\",\"audit\":[", SKELETONKEY_VERSION);
bool first = false;
audit_setuid(&n_setuid, true, &first);
audit_world_writable(&n_ww, true, &first);
audit_capabilities(&n_cap, true, &first);
audit_sudo_nopasswd(&n_sudo, true, &first);
fprintf(stdout, "],\"summary\":{\"setuid\":%d,\"world_writable\":%d,"
"\"capability\":%d,\"sudo_nopasswd\":%d}}\n",
n_setuid, n_ww, n_cap, n_sudo);
} else {
fprintf(stdout, "%-17s %-50s %s\n", "CATEGORY", "PATH", "NOTE");
fprintf(stdout, "%-17s %-50s %s\n", "--------", "----", "----");
bool first = false;
audit_setuid(&n_setuid, false, &first);
audit_world_writable(&n_ww, false, &first);
audit_capabilities(&n_cap, false, &first);
audit_sudo_nopasswd(&n_sudo, false, &first);
fprintf(stderr, "\n[*] audit summary: %d setuid, %d world-writable, "
"%d capability-set, %d sudo NOPASSWD\n",
n_setuid, n_ww, n_cap, n_sudo);
}
return 0;
}
/* --dump-offsets: walk /proc/kallsyms + /boot/System.map for the running
* kernel and emit a ready-to-paste C struct entry for kernel_table[] in
* core/offsets.c. Operators run this once on a kernel they have root on
* (or kptr_restrict=0), then upstream the entry so --full-chain works
* out-of-the-box on that build for everyone. */
static int cmd_dump_offsets(const struct skeletonkey_ctx *ctx)
{
(void)ctx;
struct skeletonkey_kernel_offsets off;
int n = skeletonkey_offsets_resolve(&off);
if (off.kbase == 0) {
fprintf(stderr,
"[-] dump-offsets: couldn't resolve a kernel base address.\n"
"\n"
" /proc/kallsyms returned all-zero addresses (kptr_restrict is\n"
" enforcing). /boot/System.map-%s wasn't readable either.\n"
"\n"
" Try one of:\n"
" sudo skeletonkey --dump-offsets\n"
" sudo sysctl kernel.kptr_restrict=0; skeletonkey --dump-offsets\n"
" sudo chmod 0644 /boot/System.map-$(uname -r); skeletonkey --dump-offsets\n",
off.kernel_release[0] ? off.kernel_release : "$(uname -r)");
return 1;
}
if (n == 0) {
fprintf(stderr,
"[-] dump-offsets: kbase resolved but no symbols. Sources tried: env,\n"
" /proc/kallsyms, /boot/System.map. Check that the kernel symbols\n"
" you need (modprobe_path / init_task / poweroff_cmd) actually exist\n"
" in the symbol files.\n");
return 1;
}
time_t now = time(NULL);
struct tm tm; localtime_r(&now, &tm);
fprintf(stdout,
"/* Generated %04d-%02d-%02d by `skeletonkey --dump-offsets`.\n"
" * Host kernel: %s%s%s\n"
" * Resolved fields: modprobe_path=%s init_task=%s cred=%s\n"
" * Paste this entry into kernel_table[] in core/offsets.c.\n"
" */\n",
tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
off.kernel_release,
off.distro[0] ? " distro=" : "",
off.distro[0] ? off.distro : "",
skeletonkey_offset_source_name(off.source_modprobe),
skeletonkey_offset_source_name(off.source_init_task),
skeletonkey_offset_source_name(off.source_cred));
fprintf(stdout,
"{ .release_glob = \"%s\",\n", off.kernel_release);
if (off.distro[0]) {
fprintf(stdout,
" .distro_match = \"%s\",\n", off.distro);
} else {
fprintf(stdout,
" .distro_match = NULL,\n");
}
if (off.modprobe_path) {
fprintf(stdout,
" .rel_modprobe_path = 0x%lx,\n",
(unsigned long)(off.modprobe_path - off.kbase));
}
if (off.poweroff_cmd) {
fprintf(stdout,
" .rel_poweroff_cmd = 0x%lx,\n",
(unsigned long)(off.poweroff_cmd - off.kbase));
}
if (off.init_task) {
fprintf(stdout,
" .rel_init_task = 0x%lx,\n",
(unsigned long)(off.init_task - off.kbase));
}
if (off.init_cred) {
fprintf(stdout,
" .rel_init_cred = 0x%lx,\n",
(unsigned long)(off.init_cred - off.kbase));
}
if (off.cred_offset_real) {
fprintf(stdout,
" .cred_offset_real = 0x%x,\n", off.cred_offset_real);
}
if (off.cred_offset_eff) {
fprintf(stdout,
" .cred_offset_eff = 0x%x,\n", off.cred_offset_eff);
}
fprintf(stdout,
"},\n");
fprintf(stderr,
"\n[+] dumped %d resolved fields. Verify offsets, then upstream this\n"
" entry via a PR to https://github.com/KaraZajac/SKELETONKEY.\n", n);
return 0;
}
/* --module-info <name>: dump everything we know about one module.
* Human-readable by default, JSON with --json. Includes the full
* detection-rule text bodies for that module. */
static int cmd_module_info(const char *name, const struct skeletonkey_ctx *ctx)
{
const struct skeletonkey_module *m = skeletonkey_module_find(name);
if (!m) {
if (ctx->json) {
fprintf(stdout, "{\"error\":\"module not found\",\"name\":\"%s\"}\n", name);
} else {
fprintf(stderr, "[-] no module '%s'. Try --list.\n", name);
}
return 1;
}
if (ctx->json) {
emit_module_json(m, true);
fputc('\n', stdout);
return 0;
}
fprintf(stdout, "name: %s\n", m->name);
fprintf(stdout, "cve: %s\n", m->cve);
fprintf(stdout, "family: %s\n", m->family);
fprintf(stdout, "kernel_range: %s\n", m->kernel_range);
fprintf(stdout, "summary: %s\n", m->summary);
/* Triage metadata sourced from CISA KEV + NVD (lookup keyed by
* m->cve). Only printed when present; mapping for older or
* recently-disclosed CVEs may be partial. */
const struct cve_metadata *md = cve_metadata_lookup(m->cve);
if (md) {
if (md->cwe)
fprintf(stdout, "cwe: %s\n", md->cwe);
if (md->attack_technique)
fprintf(stdout, "att&ck: %s%s%s\n",
md->attack_technique,
md->attack_subtechnique ? " / " : "",
md->attack_subtechnique ? md->attack_subtechnique : "");
if (md->in_kev)
fprintf(stdout, "in CISA KEV: YES (added %s)\n",
md->kev_date_added);
else
fprintf(stdout, "in CISA KEV: no\n");
}
fprintf(stdout, "operations: %s%s%s%s\n",
m->detect ? "detect " : "",
m->exploit ? "exploit " : "",
m->mitigate ? "mitigate " : "",
m->cleanup ? "cleanup " : "");
if (m->arch_support)
fprintf(stdout, "arch support: %s\n", m->arch_support);
fprintf(stdout, "detect rules: %s%s%s%s\n",
m->detect_auditd ? "auditd " : "",
m->detect_sigma ? "sigma " : "",
m->detect_yara ? "yara " : "",
m->detect_falco ? "falco " : "");
/* Verification records — VM-confirmed detect() verdicts. */
{
size_t nv = 0;
const struct verification_record *vrs =
verifications_for_module(m->name, &nv);
if (nv > 0) {
fprintf(stdout, "\n--- verified on ---\n");
for (size_t i = 0; i < nv; i++) {
const char *icon = (vrs[i].status &&
strcmp(vrs[i].status, "match") == 0) ? "" : "";
fprintf(stdout, " %s %s %s (kernel %s; %s; status: %s)\n",
icon, vrs[i].verified_at,
vrs[i].host_distro, vrs[i].host_kernel,
vrs[i].vm_box, vrs[i].status);
}
} else {
fprintf(stdout, "\n--- verified on ---\n"
" (none yet — run tools/verify-vm/verify.sh %s to add one)\n",
m->name);
}
}
if (m->opsec_notes) {
fprintf(stdout, "\n--- opsec notes ---\n%s\n", m->opsec_notes);
}
if (m->detect_auditd) {
fprintf(stdout, "\n--- auditd rules ---\n%s", m->detect_auditd);
}
if (m->detect_sigma) {
fprintf(stdout, "\n--- sigma rule ---\n%s", m->detect_sigma);
}
if (m->detect_yara) {
fprintf(stdout, "\n--- yara rule ---\n%s", m->detect_yara);
}
if (m->detect_falco) {
fprintf(stdout, "\n--- falco rule ---\n%s", m->detect_falco);
}
return 0;
}
/* Word-wrap a long paragraph at `width` columns, indenting every line by
* `indent` spaces. Writes to stdout. Used by --explain to render the
* .opsec_notes paragraph (typically 400-700 chars). */
static void print_wrapped(const char *text, int indent, int width)
{
int col = indent;
for (int i = 0; i < indent; i++) fputc(' ', stdout);
const char *p = text;
while (*p) {
const char *word_start = p;
while (*p && *p != ' ') p++;
size_t word_len = (size_t)(p - word_start);
if (col + (int)word_len > width && col > indent) {
fputc('\n', stdout);
for (int i = 0; i < indent; i++) fputc(' ', stdout);
col = indent;
}
fwrite(word_start, 1, word_len, stdout);
col += (int)word_len;
while (*p == ' ') {
if (col + 1 > width) {
fputc('\n', stdout);
for (int i = 0; i < indent; i++) fputc(' ', stdout);
col = indent;
p++;
break;
}
fputc(' ', stdout);
col++;
p++;
}
}
fputc('\n', stdout);
}
/* --explain MODULE — single-page operator briefing. Combines metadata
* (CVE / CWE / ATT&CK / KEV), host fingerprint (kernel / arch / userns
* gates), live detect() trace (the gates the module just walked, what
* the verdict was and why), OPSEC footprint (telemetry the exploit
* leaves), detection coverage (which formats have rules), and mitigation
* guidance. The intended audience is anyone who wants ONE page that
* answers "should we worry about this CVE here, what would patch it,
* and what would the SOC see if someone tried it".
*
* detect() writes its reasoning to stderr (the normal verbose path);
* --explain's structured framing goes to stdout. Redirect 2>&1 to merge. */
static int cmd_explain(const char *name, const struct skeletonkey_ctx *ctx)
{
const struct skeletonkey_module *m = skeletonkey_module_find(name);
if (!m) {
fprintf(stderr, "[-] no module '%s'. Try --list.\n", name);
return 1;
}
const struct cve_metadata *md = cve_metadata_lookup(m->cve);
/* ── header ──────────────────────────────────────────────── */
fprintf(stdout, "\n");
fprintf(stdout, "════════════════════════════════════════════════════\n");
fprintf(stdout, " %s %s\n", m->name, m->cve);
fprintf(stdout, "════════════════════════════════════════════════════\n");
fprintf(stdout, " %s\n", m->summary);
/* ── weakness ────────────────────────────────────────────── */
fprintf(stdout, "\nWEAKNESS\n");
if (md && md->cwe)
fprintf(stdout, " %s\n", md->cwe);
else
fprintf(stdout, " (no NVD CWE mapping yet)\n");
if (md && md->attack_technique)
fprintf(stdout, " MITRE ATT&CK: %s%s%s\n",
md->attack_technique,
md->attack_subtechnique ? " / " : "",
md->attack_subtechnique ? md->attack_subtechnique : "");
/* ── threat-intel context ────────────────────────────────── */
fprintf(stdout, "\nTHREAT INTEL\n");
if (md && md->in_kev)
fprintf(stdout, " ✓ In CISA Known Exploited Vulnerabilities catalog "
"(added %s)\n", md->kev_date_added);
else
fprintf(stdout, " - Not in CISA KEV (no in-the-wild exploitation "
"observed by CISA)\n");
fprintf(stdout, " Affected: %s\n", m->kernel_range);
/* ── host fingerprint summary ────────────────────────────── */
if (ctx->host) {
fprintf(stdout, "\nHOST FINGERPRINT\n");
if (ctx->host->kernel.release && ctx->host->kernel.release[0])
fprintf(stdout, " kernel: %s (%s)\n",
ctx->host->kernel.release, ctx->host->arch);
if (ctx->host->distro_pretty[0])
fprintf(stdout, " distro: %s\n", ctx->host->distro_pretty);
fprintf(stdout, " unpriv userns: %s\n",
ctx->host->unprivileged_userns_allowed ? "ALLOWED" : "blocked");
if (ctx->host->apparmor_restrict_userns)
fprintf(stdout, " apparmor: restricts unprivileged userns\n");
if (ctx->host->selinux_enforcing)
fprintf(stdout, " selinux: enforcing\n");
if (ctx->host->kernel_lockdown_active)
fprintf(stdout, " lockdown: active\n");
}
/* ── live detect trace ───────────────────────────────────── */
fprintf(stdout, "\nDETECT() TRACE (live; reads ctx->host, fires gates)\n");
fflush(stdout);
skeletonkey_result_t r = SKELETONKEY_TEST_ERROR;
if (m->detect) {
struct skeletonkey_ctx dctx = *ctx;
dctx.json = false; /* keep verbose stderr reasoning on */
r = m->detect(&dctx);
fflush(stderr);
} else {
fprintf(stdout, " (this module has no detect() — no probe to run)\n");
}
fprintf(stdout, "\nVERDICT: %s\n", result_str(r));
/* one-line interpretation for the operator */
switch (r) {
case SKELETONKEY_OK:
fprintf(stdout, " -> this host is patched / not applicable / immune.\n");
break;
case SKELETONKEY_VULNERABLE:
fprintf(stdout, " -> bug is reachable. The OPSEC section below shows what a "
"successful exploit() would leave.\n");
break;
case SKELETONKEY_PRECOND_FAIL:
fprintf(stdout, " -> a precondition check rejected this host: wrong "
"OS / arch, kernel out of range, a host-side gate "
"(userns / apparmor / selinux), or a missing carrier "
"file. See trace above for which check fired.\n");
break;
case SKELETONKEY_TEST_ERROR:
fprintf(stdout, " -> probe machinery failed; verdict unknown.\n");
break;
default: break;
}
/* ── OPSEC footprint ─────────────────────────────────────── */
if (m->opsec_notes) {
fprintf(stdout, "\nOPSEC FOOTPRINT (what exploit() leaves on this host)\n");
print_wrapped(m->opsec_notes, 2, 76);
}
/* ── empirical verification records ────────────────────────── */
{
size_t nv = 0;
const struct verification_record *vrs =
verifications_for_module(m->name, &nv);
fprintf(stdout, "\nVERIFIED ON (real-VM detect() confirmations)\n");
if (nv == 0) {
fprintf(stdout, " (none yet — run tools/verify-vm/verify.sh %s)\n",
m->name);
} else {
for (size_t i = 0; i < nv; i++) {
const char *icon = (vrs[i].status &&
strcmp(vrs[i].status, "match") == 0) ? "" : "";
fprintf(stdout, " %s %s %s — kernel %s (%s)\n",
icon, vrs[i].verified_at,
vrs[i].host_distro, vrs[i].host_kernel,
vrs[i].status);
}
}
}
/* ── detection coverage matrix ───────────────────────────── */
fprintf(stdout, "\nDETECTION COVERAGE (rules embedded in this binary)\n");
fprintf(stdout, " %s auditd %s sigma %s yara %s falco\n",
m->detect_auditd ? "" : "·",
m->detect_sigma ? "" : "·",
m->detect_yara ? "" : "·",
m->detect_falco ? "" : "·");
fprintf(stdout, " (see skeletonkey --module-info %s for rule bodies,\n"
" or skeletonkey --detect-rules --format=auditd for the full corpus)\n",
m->name);
return (int)r;
}
static int cmd_scan(const struct skeletonkey_ctx *ctx)
{
int worst = 0;
size_t n = skeletonkey_module_count();
if (!ctx->json) {
fprintf(stderr, "[*] skeletonkey scan: %zu module(s) registered\n", n);
} else {
fprintf(stdout, "{\"version\":\"%s\",\"modules\":[", SKELETONKEY_VERSION);
}
for (size_t i = 0; i < n; i++) {
const struct skeletonkey_module *m = skeletonkey_module_at(i);
if (m->detect == NULL) continue;
skeletonkey_result_t r = m->detect(ctx);
if (ctx->json) {
fprintf(stdout, "%s{\"name\":\"%s\",\"cve\":\"%s\",\"result\":\"%s\"}",
(i == 0 ? "" : ","), m->name, m->cve, result_str(r));
} else {
fprintf(stdout, "[%s] %-20s %-18s %s\n",
result_str(r), m->name, m->cve, m->summary);
}
/* track worst (highest) result code as overall exit */
if ((int)r > worst) worst = (int)r;
}
if (ctx->json) {
fprintf(stdout, "]}\n");
}
return worst;
}
/* Dump detection rules for every registered module in the requested
* format. Modules that don't ship a rule for that format are simply
* skipped (no error). Output goes to stdout so it can be redirected
* straight into /etc/audit/rules.d/, the SIEM, etc. */
static int cmd_detect_rules(enum detect_format fmt)
{
static const char *fmt_names[] = {
[FMT_AUDITD] = "auditd",
[FMT_SIGMA] = "sigma",
[FMT_YARA] = "yara",
[FMT_FALCO] = "falco",
};
size_t n = skeletonkey_module_count();
fprintf(stdout, "# SKELETONKEY detection rules — format: %s\n", fmt_names[fmt]);
fprintf(stdout, "# Generated from %zu registered modules\n", n);
fprintf(stdout, "# AUTHORIZED-TESTING tool; see docs/ETHICS.md\n\n");
/* Dedup by pointer: family-shared rule strings (e.g. all 5
* copy_fail_family modules share one auditd rule string) would
* otherwise emit identical blocks once per module. */
const char *seen[64] = {0};
size_t n_seen = 0;
int emitted = 0;
for (size_t i = 0; i < n; i++) {
const struct skeletonkey_module *m = skeletonkey_module_at(i);
const char *rules = NULL;
switch (fmt) {
case FMT_AUDITD: rules = m->detect_auditd; break;
case FMT_SIGMA: rules = m->detect_sigma; break;
case FMT_YARA: rules = m->detect_yara; break;
case FMT_FALCO: rules = m->detect_falco; break;
}
if (rules == NULL) continue;
/* Already emitted? */
bool dup = false;
for (size_t k = 0; k < n_seen; k++) {
if (seen[k] == rules) { dup = true; break; }
}
if (dup) {
fprintf(stdout, "# === %s (%s) — see family rules above ===\n\n",
m->name, m->cve);
continue;
}
if (n_seen < sizeof(seen)/sizeof(seen[0])) seen[n_seen++] = rules;
fprintf(stdout, "# === %s (%s) ===\n", m->name, m->cve);
fputs(rules, stdout);
fputc('\n', stdout);
emitted++;
}
fprintf(stderr, "[*] emitted detection rules for %d / %zu module(s) (format: %s)\n",
emitted, n, fmt_names[fmt]);
return 0;
}
/* --auto: scan, rank by safety, run safest vulnerable exploit. */
static int module_safety_rank(const char *n)
{
/* Higher = safer. Run highest-ranked vulnerable module. */
if (!strcmp(n, "pwnkit")) return 100; /* userspace, no kernel */
if (!strcmp(n, "sudoedit_editor")) return 99; /* structural argv */
if (!strcmp(n, "cgroup_release_agent")) return 98; /* structural, no offsets */
if (!strcmp(n, "overlayfs_setuid")) return 97; /* structural setuid */
if (!strcmp(n, "overlayfs")) return 96; /* userns + xattr */
if (!strcmp(n, "pack2theroot")) return 95; /* userspace D-Bus TOCTOU; dpkg + /tmp SUID footprint */
if (!strcmp(n, "dirty_pipe")) return 90; /* page-cache write */
if (!strcmp(n, "dirty_cow")) return 89;
if (!strncmp(n, "copy_fail", 9) ||
!strncmp(n, "dirty_frag", 10)) return 88; /* verified page-cache writes */
if (!strcmp(n, "dirtydecrypt") ||
!strcmp(n, "fragnesia")) return 87; /* ported page-cache writes; version-pinned detect, exploit NOT VM-verified */
if (!strcmp(n, "ptrace_traceme")) return 85; /* userspace cred race */
if (!strcmp(n, "sudo_samedit")) return 80; /* heap-tuned, may crash sudo */
if (!strcmp(n, "af_unix_gc")) return 25; /* kernel race, low win% */
if (!strcmp(n, "stackrot")) return 15; /* very low win% */
if (!strcmp(n, "entrybleed")) return 0; /* leak only, not LPE */
return 50; /* kernel primitives — middle of pack */
}
/* Per-detect timeout: a probe that hangs (network blocking, deadlocked
* fork-probe, kernel-side stall) must NOT freeze --auto. 15s is well
* above any honest active probe (fragnesia's full XFRM setup is ~500ms,
* dirtydecrypt's rxgk handshake ~1s) but short enough that the scan
* still finishes within ~7-8 minutes even if every module hits the cap. */
#define SKELETONKEY_DETECT_TIMEOUT_SECS 15
/* Run a module's detect() in a forked child so a SIGILL/SIGSEGV/etc.
* in one detector cannot tear down the dispatcher. Also installs an
* alarm(15) so a hung probe cannot stall the scan.
*
* The verdict travels back via the child's exit status
* (skeletonkey_result_t values fit in 0..5). On a crash, returns
* SKELETONKEY_TEST_ERROR; *crashed_signal is set to the terminating
* signal (0 if exited normally), *timed_out is true if the signal
* was SIGALRM (the detect-timeout fired).
*
* This matters because --auto auto-enables active probes, which can
* exercise CPU instructions (entrybleed's prefetchnta sweep) or
* kernel paths (XFRM ESP-in-TCP setup) that may misbehave under
* emulation or hardened containers, or stall on a frozen socket.
* Without isolation + timeout, one bad probe stops the whole scan
* and the operator never sees the rest of the verdict table. */
static skeletonkey_result_t run_detect_isolated(
const struct skeletonkey_module *m,
const struct skeletonkey_ctx *ctx,
int *crashed_signal,
bool *timed_out)
{
*crashed_signal = 0;
*timed_out = false;
pid_t pid = fork();
if (pid < 0) {
perror("fork");
return SKELETONKEY_TEST_ERROR;
}
if (pid == 0) {
/* SIGALRM default action is termination — perfect kill-switch. */
alarm(SKELETONKEY_DETECT_TIMEOUT_SECS);
skeletonkey_result_t r = m->detect(ctx);
fflush(NULL);
_exit((int)r);
}
int st;
if (waitpid(pid, &st, 0) < 0) return SKELETONKEY_TEST_ERROR;
if (WIFEXITED(st)) return (skeletonkey_result_t)WEXITSTATUS(st);
if (WIFSIGNALED(st)) {
*crashed_signal = WTERMSIG(st);
if (*crashed_signal == SIGALRM) *timed_out = true;
}
return SKELETONKEY_TEST_ERROR;
}
/* Run a module callback (exploit/mitigate/cleanup) in a forked child.
* Two crash-safety properties:
* - SIGSEGV/SIGILL/etc. in the callback is contained.
* - --auto's "try next-safest on EXPLOIT_FAIL" fallback path actually
* runs even if the picked exploit dies hard.
*
* Result communication is via a one-byte pipe with FD_CLOEXEC on the
* write end:
* - If the callback returns normally, the child writes the result
* byte before _exit; the parent reads it. Trusted result code.
* - If the callback execve()s into a target (dirty_pipe → su,
* pack2theroot → /tmp/.suid_bash), FD_CLOEXEC closes the write
* end as part of the exec transfer; the parent's read() gets
* EOF. We then know the child exec'd code and report EXPLOIT_OK
* regardless of what shell exit code the exec'd-into program
* returns when the operator detaches.
* - If the child died of a signal, that's a crash; report it. */
static skeletonkey_result_t run_callback_isolated(
const char *label,
skeletonkey_result_t (*fn)(const struct skeletonkey_ctx *),
const struct skeletonkey_ctx *ctx,
int *crashed_signal,
bool *exec_path)
{
(void)label;
*crashed_signal = 0;
*exec_path = false;
int pfd[2];
if (pipe(pfd) < 0) {
/* Plumbing failed — fall back to direct call. The crash-safety
* property is degraded for this one invocation, but the
* dispatcher would have crashed anyway if pipe() fails. */
return fn(ctx);
}
/* FD_CLOEXEC: if child execve's, the kernel closes pfd[1] before
* handing control to the new image, so the new image cannot
* inadvertently write garbage and the parent observes EOF. */
if (fcntl(pfd[1], F_SETFD, FD_CLOEXEC) < 0) {
close(pfd[0]); close(pfd[1]);
return fn(ctx);
}
pid_t pid = fork();
if (pid < 0) {
close(pfd[0]); close(pfd[1]);
perror("fork");
return SKELETONKEY_TEST_ERROR;
}
if (pid == 0) {
close(pfd[0]);
skeletonkey_result_t r = fn(ctx);
/* If we get here, fn didn't exec. Report the code. */
unsigned char code = (unsigned char)r;
ssize_t w = write(pfd[1], &code, 1);
(void)w;
close(pfd[1]);
fflush(NULL);
_exit((int)r);
}
close(pfd[1]);
unsigned char code = 0;
ssize_t n = read(pfd[0], &code, 1);
close(pfd[0]);
int st;
waitpid(pid, &st, 0);
if (n == 1)
return (skeletonkey_result_t)code;
/* No byte read → child either exec'd (FD_CLOEXEC closed pfd[1])
* or crashed before reaching the write. Distinguish via wait
* status. */
if (WIFSIGNALED(st)) {
*crashed_signal = WTERMSIG(st);
return SKELETONKEY_EXPLOIT_FAIL;
}
/* Normal exit without writing → must have exec'd. We achieved
* code execution; treat as EXPLOIT_OK regardless of the shell's
* subsequent exit code. */
*exec_path = true;
return SKELETONKEY_EXPLOIT_OK;
}
/* Host fingerprint parsing (ID / VERSION_ID / kernel / arch) lives in
* core/host.c; cmd_auto consults ctx->host via the shared banner. */
static int cmd_auto(struct skeletonkey_ctx *ctx)
{
if (!ctx->authorized && !ctx->dry_run) {
fprintf(stderr,
"[-] --auto requires --i-know (or --dry-run for a preview that never fires).\n"
" About to attempt root via the safest available LPE on this host.\n"
" Authorized testing only. See docs/ETHICS.md.\n");
return 1;
}
if (geteuid() == 0) {
fprintf(stderr, "[i] auto: already running as root; nothing to do.\n");
return 0;
}
/* Active probes give --auto a more accurate verdict on modules that
* implement them (dirty_pipe, the copy_fail family, dirtydecrypt,
* fragnesia, overlayfs). Each per-module probe is documented safe:
* /tmp sentinel files + fork-isolated namespace mounts. No real
* system state is corrupted by the scan. Without this, --auto can
* miss vulnerabilities that a version-only check would flag as
* indeterminate (TEST_ERROR), or accept distro silent backports
* that the version check is fooled by. */
bool prev_active = ctx->active_probe;
ctx->active_probe = true;
/* Two-line host fingerprint banner (identity + capability gates). */
skeletonkey_host_print_banner(ctx->host, ctx->json);
fprintf(stderr, "[*] auto: active probes enabled — brief /tmp file "
"touches and fork-isolated namespace probes\n");
fprintf(stderr, "[*] auto: scanning %zu modules for vulnerabilities...\n",
skeletonkey_module_count());
struct cand { const struct skeletonkey_module *m; int rank; } cands[64];
int nc = 0;
int n_vuln = 0, n_ok = 0, n_precond = 0, n_test = 0;
int n_crash = 0, n_timeout = 0, n_other = 0;
size_t n = skeletonkey_module_count();
for (size_t i = 0; i < n; i++) {
const struct skeletonkey_module *m = skeletonkey_module_at(i);
if (!m->detect || !m->exploit) continue;
int sig = 0;
bool timed_out = false;
skeletonkey_result_t r = run_detect_isolated(m, ctx, &sig, &timed_out);
if (sig != 0) {
const char *why = timed_out ? "timed out" : "crashed";
fprintf(stderr, "[?] auto: %-22s detect() %s "
"(signal %d) — continuing\n",
m->name, why, sig);
if (timed_out) n_timeout++;
else n_crash++;
continue;
}
switch (r) {
case SKELETONKEY_VULNERABLE:
if (nc < 64) {
cands[nc].m = m;
cands[nc].rank = module_safety_rank(m->name);
fprintf(stderr, "[+] auto: %-22s VULNERABLE (safety rank %d)\n",
m->name, cands[nc].rank);
nc++;
} else {
fprintf(stderr, "[+] auto: %-22s VULNERABLE (overflow; not "
"considered for pick)\n", m->name);
}
n_vuln++;
break;
case SKELETONKEY_OK:
fprintf(stderr, "[ ] auto: %-22s patched or not applicable\n",
m->name);
n_ok++;
break;
case SKELETONKEY_PRECOND_FAIL:
fprintf(stderr, "[ ] auto: %-22s precondition not met\n", m->name);
n_precond++;
break;
case SKELETONKEY_TEST_ERROR:
fprintf(stderr, "[?] auto: %-22s indeterminate "
"(detector could not decide)\n", m->name);
n_test++;
break;
default:
fprintf(stderr, "[?] auto: %-22s %s\n", m->name, result_str(r));
n_other++;
break;
}
}
/* Restore caller's --active setting before we call exploit(). The
* exploit() of each module may use ctx->active_probe with different
* semantics than detect(); we owned this flag only for the scan. */
ctx->active_probe = prev_active;
fprintf(stderr, "\n[*] auto: scan summary — %d vulnerable, %d patched/"
"n.a., %d precondition-fail, %d indeterminate%s\n",
n_vuln, n_ok, n_precond, n_test,
n_other ? " (+other)" : "");
if (n_crash > 0)
fprintf(stderr, "[!] auto: %d module(s) crashed during detect "
"— dispatcher recovered via fork isolation\n", n_crash);
if (n_timeout > 0)
fprintf(stderr, "[!] auto: %d module(s) timed out (>%ds) during "
"detect — dispatcher recovered\n",
n_timeout, SKELETONKEY_DETECT_TIMEOUT_SECS);
if (nc == 0) {
if (n_test > 0) {
fprintf(stderr, "[i] auto: %d module(s) returned indeterminate. "
"Try `skeletonkey --exploit <name> --i-know` if "
"you know the host is vulnerable.\n", n_test);
}
fprintf(stderr, "[-] auto: no confirmed-vulnerable modules. Host "
"appears patched.\n");
return 0;
}
/* Sort descending by rank (safest first). */
for (int i = 0; i < nc; i++)
for (int j = i + 1; j < nc; j++)
if (cands[j].rank > cands[i].rank) {
struct cand t = cands[i]; cands[i] = cands[j]; cands[j] = t;
}
const struct skeletonkey_module *pick = cands[0].m;
if (ctx->dry_run) {
fprintf(stderr,
"\n[*] auto: %d vulnerable module(s) found. Safest is '%s' (rank %d).\n"
"[*] auto: --dry-run: would launch `--exploit %s --i-know`; not firing.\n",
nc, pick->name, cands[0].rank, pick->name);
if (nc > 1) {
fprintf(stderr, "[i] auto: other candidates (ranked):\n");
for (int i = 1; i < nc; i++)
fprintf(stderr, " %-22s safety rank %d\n",
cands[i].m->name, cands[i].rank);
}
return 0;
}
fprintf(stderr,
"\n[*] auto: %d vulnerable module(s) found. Safest is '%s' (rank %d).\n"
"[*] auto: launching --exploit %s...\n\n",
nc, pick->name, cands[0].rank, pick->name);
int xsig = 0;
bool exec_path = false;
skeletonkey_result_t r = run_callback_isolated(
"exploit", pick->exploit, ctx, &xsig, &exec_path);
if (xsig != 0) {
fprintf(stderr, "\n[!] auto: %s exploit crashed (signal %d) — "
"dispatcher recovered via fork isolation\n",
pick->name, xsig);
} else if (exec_path) {
fprintf(stderr, "\n[*] auto: %s exploit transferred to spawned "
"target (shell exited cleanly) — EXPLOIT_OK\n",
pick->name);
} else {
fprintf(stderr, "\n[*] auto: %s exploit returned %s\n",
pick->name, result_str(r));
}
if (r == SKELETONKEY_EXPLOIT_OK) return 5;
if (r == SKELETONKEY_EXPLOIT_FAIL && nc > 1) {
fprintf(stderr, "[i] auto: %d more candidate(s) available — try one manually:\n", nc - 1);
for (int i = 1; i < nc; i++)
fprintf(stderr, " skeletonkey --exploit %s --i-know\n", cands[i].m->name);
}
return (r == SKELETONKEY_EXPLOIT_FAIL) ? 3 : (int)r;
}
static int cmd_one(const struct skeletonkey_module *m, const char *op,
const struct skeletonkey_ctx *ctx)
{
if (ctx->dry_run) {
fprintf(stderr, "[*] %s: --dry-run: would run --%s; not firing.\n",
m->name, op);
return 0;
}
skeletonkey_result_t (*fn)(const struct skeletonkey_ctx *) = NULL;
if (strcmp(op, "exploit") == 0) fn = m->exploit;
else if (strcmp(op, "mitigate") == 0) fn = m->mitigate;
else if (strcmp(op, "cleanup") == 0) fn = m->cleanup;
if (fn == NULL) {
fprintf(stderr, "[-] module '%s' has no %s operation\n", m->name, op);
return 1;
}
int sig = 0;
bool exec_path = false;
skeletonkey_result_t r = run_callback_isolated(op, fn, ctx, &sig, &exec_path);
if (sig != 0)
fprintf(stderr, "[!] %s --%s crashed (signal %d) — recovered\n",
m->name, op, sig);
else if (exec_path)
fprintf(stderr, "[*] %s --%s transferred to spawned target — EXPLOIT_OK\n",
m->name, op);
else
fprintf(stderr, "[*] %s --%s result: %s\n",
m->name, op, result_str(r));
return (int)r;
}
int main(int argc, char **argv)
{
/* Bring up the module registry. New module families register
* themselves via skeletonkey_register_all_modules() in
* core/registry.c — add the new register_*() call there so the
* test binary picks it up automatically. */
skeletonkey_register_all_modules();
enum mode mode = MODE_SCAN;
struct skeletonkey_ctx ctx = {0};
const char *target = NULL;
int i_know = 0;
/* Probe the host once, up front. ctx.host is a stable pointer
* shared by every module callback; populating now means each
* detect() sees the same fingerprint and no module has to re-do
* uname/getpwuid/sysctl reads. See core/host.{h,c}. */
ctx.host = skeletonkey_host_get();
enum detect_format dr_fmt = FMT_AUDITD;
static struct option longopts[] = {
{"scan", no_argument, 0, 'S'},
{"list", no_argument, 0, 'L'},
{"exploit", required_argument, 0, 'E'},
{"mitigate", required_argument, 0, 'M'},
{"cleanup", required_argument, 0, 'C'},
{"detect-rules", no_argument, 0, 'D'},
{"module-info", required_argument, 0, 'I'},
{"audit", no_argument, 0, 'A'},
{"dump-offsets", no_argument, 0, 8 },
{"auto", no_argument, 0, 9 },
{"format", required_argument, 0, 6 },
{"i-know", no_argument, 0, 1 },
{"active", no_argument, 0, 2 },
{"no-shell", no_argument, 0, 3 },
{"json", no_argument, 0, 4 },
{"no-color", no_argument, 0, 5 },
{"full-chain", no_argument, 0, 7 },
{"dry-run", no_argument, 0, 10 },
{"explain", required_argument, 0, 11 },
{"version", no_argument, 0, 'V'},
{"help", no_argument, 0, 'h'},
{0, 0, 0, 0}
};
int c, opt_idx;
while ((c = getopt_long(argc, argv, "SLDAE:M:C:I:Vh", longopts, &opt_idx)) != -1) {
switch (c) {
case 'S': mode = MODE_SCAN; break;
case 'L': mode = MODE_LIST; break;
case 'D': mode = MODE_DETECT_RULES; break;
case 'A': mode = MODE_AUDIT; break;
case 'I': mode = MODE_MODULE_INFO; target = optarg; break;
case 'E': mode = MODE_EXPLOIT; target = optarg; break;
case 'M': mode = MODE_MITIGATE; target = optarg; break;
case 'C': mode = MODE_CLEANUP; target = optarg; break;
case 1 : i_know = 1; ctx.authorized = true; break;
case 2 : ctx.active_probe = true; break;
case 3 : ctx.no_shell = true; break;
case 4 : ctx.json = true; break;
case 5 : ctx.no_color = true; break;
case 7 : ctx.full_chain = true; break;
case 8 : mode = MODE_DUMP_OFFSETS; break;
case 9 : mode = MODE_AUTO; ctx.authorized = i_know ? true : ctx.authorized; break;
case 10 : ctx.dry_run = true; break;
case 11 : mode = MODE_EXPLAIN; target = optarg; break;
case 6 :
if (strcmp(optarg, "auditd") == 0) dr_fmt = FMT_AUDITD;
else if (strcmp(optarg, "sigma") == 0) dr_fmt = FMT_SIGMA;
else if (strcmp(optarg, "yara") == 0) dr_fmt = FMT_YARA;
else if (strcmp(optarg, "falco") == 0) dr_fmt = FMT_FALCO;
else { fprintf(stderr, "[-] unknown --format: %s\n", optarg); return 1; }
break;
case 'V': printf("skeletonkey %s\n", SKELETONKEY_VERSION); return 0;
case 'h': mode = MODE_HELP; break;
default: usage(argv[0]); return 1;
}
}
if (mode == MODE_HELP) {
fputs(BANNER, stderr);
usage(argv[0]);
return 0;
}
if (!ctx.json) fputs(BANNER, stderr);
if (mode == MODE_SCAN) return cmd_scan(&ctx);
if (mode == MODE_LIST) return cmd_list(&ctx);
if (mode == MODE_MODULE_INFO) return cmd_module_info(target, &ctx);
if (mode == MODE_EXPLAIN) return cmd_explain(target, &ctx);
if (mode == MODE_DETECT_RULES) return cmd_detect_rules(dr_fmt);
if (mode == MODE_AUDIT) return cmd_audit(&ctx);
if (mode == MODE_AUTO) return cmd_auto(&ctx);
if (mode == MODE_DUMP_OFFSETS) return cmd_dump_offsets(&ctx);
/* --exploit / --mitigate / --cleanup all take a target */
if (target == NULL) {
fprintf(stderr, "[-] mode requires a module name\n");
return 1;
}
const struct skeletonkey_module *m = skeletonkey_module_find(target);
if (m == NULL) {
fprintf(stderr, "[-] no module '%s'. Try --list.\n", target);
return 1;
}
if (mode == MODE_EXPLOIT) {
if (!i_know) {
fprintf(stderr,
"[-] --exploit requires --i-know. This will attempt to gain\n"
" root and corrupt /etc/passwd in the page cache.\n"
" Authorized testing only. See docs/ETHICS.md.\n");
return 1;
}
return cmd_one(m, "exploit", &ctx);
}
if (mode == MODE_MITIGATE) return cmd_one(m, "mitigate", &ctx);
if (mode == MODE_CLEANUP) return cmd_one(m, "cleanup", &ctx);
usage(argv[0]);
return 1;
}