leviathan
9593d90385
Breaking change. Tool name, binary name, function/type names,
constant names, env vars, header guards, file paths, and GitHub
repo URL all rebrand IAMROOT → SKELETONKEY.
Changes:
- All "IAMROOT" → "SKELETONKEY" (constants, env vars, enum
values, docs, comments)
- All "iamroot" → "skeletonkey" (functions, types, paths, CLI)
- iamroot.c → skeletonkey.c
- modules/*/iamroot_modules.{c,h} → modules/*/skeletonkey_modules.{c,h}
- tools/iamroot-fleet-scan.sh → tools/skeletonkey-fleet-scan.sh
- Binary "iamroot" → "skeletonkey"
- GitHub URL KaraZajac/IAMROOT → KaraZajac/SKELETONKEY
- .gitignore now expects build output named "skeletonkey"
- /tmp/iamroot-* tmpfiles → /tmp/skeletonkey-*
- Env vars IAMROOT_MODPROBE_PATH etc. → SKELETONKEY_*
New ASCII skeleton-key banner (horizontal key icon + ANSI Shadow
SKELETONKEY block letters) replaces the IAMROOT banner in
skeletonkey.c and README.md.
VERSION: 0.3.1 → 0.4.0 (breaking).
Build clean on Debian 6.12.86. `skeletonkey --version` → 0.4.0.
All 24 modules still register; no functional code changes — pure
rename + banner refresh.
58 lines
2.2 KiB
Markdown
58 lines
2.2 KiB
Markdown
# Pwnkit — CVE-2021-4034
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> 🔵 **DETECT-ONLY** as of 2026-05-16. Full exploit follows.
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## Summary
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Polkit's `pkexec` parses argv assuming argc ≥ 1. With `argc == 0`, the
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parsing reads past `argv[0]` into the contiguous envp region, treating
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the first env string as if it were argv[0]. By placing `GCONV_PATH=`
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crafted entries in the environment and naming a controlled file such
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that libc's iconv() loads it as a gconv module, an unprivileged user
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gets code execution as root via the setuid pkexec binary.
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Disclosed by Qualys 2022-01-25. Bug existed since pkexec's first
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release in 2009 — affects every distribution shipping a vulnerable
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polkit until 0.121 (or distro backport).
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## Affected versions
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- **All polkit ≤ 0.120** (i.e., pkexec from 2009 onward) before the
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fix landed.
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- Patched in upstream **polkit 0.121** (2022-01-25).
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- Distro backports vary:
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- Ubuntu: 0.105-26ubuntu1.3 (focal), 0.105-31ubuntu0.1 (impish), etc.
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- Debian: 0.105-31+deb11u1 (bullseye), 0.105-26+deb10u1 (buster)
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- RHEL: polkit-0.115-13.el7_9 (RHEL 7), polkit-0.117-9.el8_5.1 (RHEL 8)
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## SKELETONKEY detect logic (current)
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1. Resolve pkexec binary (`/usr/bin/pkexec` or `which pkexec`)
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2. If not present → SKELETONKEY_OK (no attack surface)
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3. Run `pkexec --version` and parse version
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4. Compare to known-fixed thresholds; report VULNERABLE if below
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## Exploit logic (follow-up)
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Canonical Qualys / public Pwnkit PoC:
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1. Build a malicious shared object that `exit(setuid(0)); system("/bin/sh")`
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2. Build a `GCONV_PATH=./X` env entry plus `CHARSET=X` so libc's
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iconv (used by pkexec for argv decoding) loads our .so
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3. `execve("/usr/bin/pkexec", { NULL }, envp)` — argc=0 triggers the
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read past argv[0], which sees our GCONV_PATH crafted string, then
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pkexec gives us root context, the gconv module loads our .so as
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root, we drop to a shell
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~200 lines including the embedded .so generator. Phase 7 follow-up
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commit lands the full version.
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## Detection rules (shipped)
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`detect/auditd.rules` — flags pkexec invocations from non-root.
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## References
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- https://blog.qualys.com/vulnerabilities-threat-research/2022/01/25/pwnkit-local-privilege-escalation-vulnerability-discovered-in-polkits-pkexec-cve-2021-4034
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- https://nvd.nist.gov/vuln/detail/CVE-2021-4034
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