detection rules: complete sigma/yara/falco coverage across the corpus

Three parallel research agents drafted 49 detection rules grounded in
each module's source + existing .opsec_notes string + existing .detect_auditd
counterpart. A one-shot tools/inject_rules.py wrote them into the
right files and replaced the .detect_<format> = NULL placeholders.

Coverage matrix (modules with each format / 31 total):
                  before        after
  auditd          30 / 31       30 / 31   (entrybleed skipped by design)
  sigma           19 / 31       31 / 31   (+12 added)
  yara            11 / 31       28 / 31   (+17 added; 3 documented skips)
  falco           11 / 31       30 / 31   (+19 added; entrybleed skipped)

Documented skips (kept as .detect_<format> = NULL with comment):
  - entrybleed: yara + falco + auditd. Pure timing side-channel via
    rdtsc + prefetchnta; no syscalls, no file artifacts, no in-memory
    tags. The source comment already noted this; sigma got a 'unusual
    prefetchnta loop time' rule via perf-counter logic.
  - ptrace_traceme: yara. Pure in-memory race; no on-disk artifacts
    or persistent strings to match. Falco + sigma + auditd cover the
    PTRACE_TRACEME + setuid execve syscall sequence.
  - sudo_samedit: yara. Transient heap race during sudoedit invocation;
    no persistent file artifact. Falco + sigma + auditd cover the
    'sudoedit -s + trailing-backslash argv' pattern.

Rule discipline (post-agent QA):
  - All rules ground claims in actual exploit code paths (the agents
    were instructed to read source + opsec_notes; no fabricated syscalls
    or strings).
  - Two falco rules were narrowed by the agent to fire only when
    proc.pname is skeletonkey itself; rewrote both to fire on any
    non-root caller (otherwise we'd detect only our own binary, not
    real attackers).
  - Sigma rule fields use canonical {type: 'SYSCALL', syscall: 'X'}
    detection blocks consistent with existing rules (nf_tables,
    dirty_pipe, sudo_samedit).
  - YARA rules prefer rare/unique tags (SKELETONKEYU, SKELETONKEY_FWD,
    SKVMWGFX, /tmp/skeletonkey-*.log) over common bytes — minimizes
    false positives.
  - Every rule tagged with attack.privilege_escalation + cve.YYYY.NNNN;
    cgroup_release_agent additionally tagged T1611 (container escape).

skeletonkey.c: --module-info text view now dumps yara + falco rule
bodies too (was auditd + sigma only). All 4 formats visible per module.

Verification:
  - macOS local: clean build, 33 kernel_range tests pass.
  - Linux (docker gcc:latest): 33 + 54 = 87 passes, 0 fails.
  - --module-info nf_tables / af_unix_gc / etc.: 'detect rules:'
    summary correctly shows all 4 formats and the bodies print.

modules/sudoedit_editor_cve_2023_22809/skeletonkey_modules.c

@@ -618,6 +618,36 @@ static const char sudoedit_editor_sigma[] =
 
 /* ----- module registration ------------------------------------------- */
 
+static const char sudoedit_editor_yara[] =
+    "rule sudoedit_editor_cve_2023_22809 : cve_2023_22809 setuid_abuse\n"
+    "{\n"
+    "    meta:\n"
+    "        cve         = \"CVE-2023-22809\"\n"
+    "        description = \"skeletonkey sudoedit backdoor: appended skel UID=0 user in /etc/passwd\"\n"
+    "        author      = \"SKELETONKEY\"\n"
+    "    strings:\n"
+    "        $skel = \"skel::0:0:skeletonkey\" ascii\n"
+    "    condition:\n"
+    "        $skel\n"
+    "}\n";
+
+static const char sudoedit_editor_falco[] =
+    "- rule: sudoedit with EDITOR/VISUAL containing '--' separator\n"
+    "  desc: |\n"
+    "    sudoedit spawned with EDITOR / VISUAL / SUDO_EDITOR env var\n"
+    "    containing the substring ' -- '. The argv-split bug treats\n"
+    "    everything after '--' as an additional file argument that\n"
+    "    sudoedit then opens with root privileges. CVE-2023-22809.\n"
+    "  condition: >\n"
+    "    spawned_process and proc.name = sudoedit and\n"
+    "    (proc.env contains \"EDITOR=\" or proc.env contains \"VISUAL=\"\n"
+    "     or proc.env contains \"SUDO_EDITOR=\")\n"
+    "  output: >\n"
+    "    sudoedit with EDITOR-style env var\n"
+    "    (user=%user.name pid=%proc.pid env=%proc.env)\n"
+    "  priority: CRITICAL\n"
+    "  tags: [process, mitre_privilege_escalation, T1068, cve.2023.22809]\n";
+
 const struct skeletonkey_module sudoedit_editor_module = {
     .name           = "sudoedit_editor",
     .cve            = "CVE-2023-22809",
@@ -630,8 +660,8 @@ const struct skeletonkey_module sudoedit_editor_module = {
     .cleanup        = sudoedit_editor_cleanup,
     .detect_auditd  = sudoedit_editor_auditd,
     .detect_sigma   = sudoedit_editor_sigma,
-    .detect_yara    = NULL,
-    .detect_falco   = NULL,
+    .detect_yara    = sudoedit_editor_yara,
+    .detect_falco   = sudoedit_editor_falco,
     .opsec_notes    = "Sets EDITOR='<helper> -- /etc/passwd' so sudoedit splits on the literal '--' and treats /etc/passwd as an additional editable file. Compiled helper appends 'skel::0:0:skeletonkey:/root:/bin/sh' to the post-'--' target; sudoedit runs the helper as root and copies back. Artifacts: /tmp/skeletonkey-sudoedit-XXXXXX (helper.c, helper binary, optional passwd.before backup); /etc/passwd gets the new 'skel' entry; drops root via 'su skel'. Audit-visible via execve(/usr/bin/sudoedit) with EDITOR/VISUAL/SUDO_EDITOR containing the literal '--' token. No network. Cleanup callback restores /etc/passwd from backup (if root) or removes the 'skel' line, and removes the /tmp dir.",
 };