modules: add sudo_host (CVE-2025-32462, Stratascale sudo --host policy bypass)

Second new module this cycle; sibling of sudo_chwoot (CVE-2025-32463, same Stratascale/Rich Mirch disclosure). sudo's -h/--host option — meant only to pair with -l/--list — was honored when running a command, so a sudoers rule scoped to a host other than the current machine (and not ALL) is usable via 'sudo -h <host> <cmd>' for local root. Affects sudo 1.8.8 -> 1.9.17p0; fixed 1.9.17p1. CWE-863, CVSS 8.8 (not in KEV). detect(): version-gate [1.8.8, 1.9.17p0] via ctx->host->sudo_version (the host-restricted rule itself isn't probeable unprivileged, so VULNERABLE means 'vulnerable sudo present'). exploit(): discovers an abusable host-restricted rule from readable sudoers (or SKELETONKEY_SUDO_HOST), witnesses with 'sudo -n -h <host> id -u', pops 'sudo -h <host> /bin/bash' (SKELETONKEY_SUDO_CMD) only on a uid-0 witness; honest EXPLOIT_FAIL + operator guidance otherwise. Shared 'sudo' family; structural, arch=any; safety rank 96. auditd/sigma/falco rules, NOTICE.md (Rich Mirch / Stratascale) + MODULE.md, 4 detect() test rows. Wiring: registry, Makefile, cve_metadata (+JSON), verify-vm/targets.yaml (ubuntu1804 sudo 1.8.21p2 target, sweep pending). Docs: README + CVES.md + docs/index.html counts 40->41 modules / 35->36 CVEs; not-yet-verified lists + corpus pill.
2026-06-02 08:43:09 -04:00
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+# sudo_host — CVE-2025-32462
+
+sudo `-h`/`--host` option honored beyond `-l` → abuse a host-restricted
+sudoers rule for local root.
+
+## The bug
+
+`sudo -h <host>` (a.k.a. `--host`) exists so that, combined with `-l`,
+you can list your sudo privileges *as they would apply on another host*.
+The flaw: sudo also consulted the `-h` value when **running a command**
+(and in `sudoedit`), so the host portion of a sudoers rule — normally
+fixed to the machine you're on — becomes attacker-chosen.
+
+If your sudoers contains a rule like:
+
+```
+alice  webhost01 = (root) /usr/bin/systemctl
+```
+
+then on a *different* machine `alice` normally can't use it. With the
+bug, `sudo -h webhost01 /usr/bin/systemctl ...` runs as root on the
+local box. With a broader rule (`webhost01 = (ALL) ALL`), `sudo -h
+webhost01 /bin/bash` is a root shell.
+
+This matters most where one sudoers file (or LDAP/SSSD sudoers) is shared
+across a fleet and rules are scoped per host.
+
+## Affected range
+
+| | |
+|---|---|
+| Affected | sudo 1.8.8 → 1.9.17p0 (~12-year-old behaviour) |
+| Fixed | sudo 1.9.17p1 |
+| Weakness | CWE-863 (Incorrect Authorization) |
+| Severity | CVSS 8.8 (High); not in CISA KEV |
+
+## Trigger / detection
+
+`detect()` reads the sudo version (shared host fingerprint, else a live
+`sudo --version`) and returns VULNERABLE inside `[1.8.8, 1.9.17p0]`,
+OK otherwise. The exploitable precondition — a host-restricted sudoers
+rule — is not reliably probeable from an unprivileged context, so the
+empirical confirmation lives in the exploit path.
+
+`exploit()`:
+1. Resolves the host token to abuse: `SKELETONKEY_SUDO_HOST` env var, or
+   a best-effort scan of readable `/etc/sudoers` + `/etc/sudoers.d/*` for
+   a user-spec whose host is neither the current hostname nor `ALL`.
+2. Witnesses with `sudo -n -h <host> id -u` (non-interactive).
+3. On a uid-0 witness, execs `sudo -h <host> /bin/bash`
+   (override the command with `SKELETONKEY_SUDO_CMD`).
+
+Returns `EXPLOIT_FAIL` with operator guidance when no abusable rule is
+discoverable — it never fabricates root.
+
+## Fix / mitigation
+
+Upgrade sudo to 1.9.17p1 or later. There is no safe runtime toggle for
+the `-h` behaviour short of the patch.
+
+## Credit
+
+Rich Mirch — Stratascale CRU (2025-06-30). See `NOTICE.md`.