feat: flag setuid and sudoers escalation

CHANGELOG.md

@@ -15,6 +15,7 @@ All notable changes to this project are documented here, following
 
 ### Added
 
+- **SKILL-SH-011**: flag setuid changes, root-owned payloads, and writes to `/etc/sudoers`.
 - **SKILL-SEC-007**: flag references to bash, zsh, and PowerShell ConsoleHost history files.
 - **SKILL-OBF-004**: flag PowerShell `-EncodedCommand` / `-enc` and `xxd -r` output piped into a shell.
 - **SKILL-INJ-010**: flag prose that fetches remote instructions and tells the agent to follow them.

src/rules.js

@@ -217,6 +217,11 @@ export const RULES = [
     remediation: "Writing to authorized_keys or under ~/.ssh grants persistent remote login. Never ship this in a skill.",
     pattern: /(authorized_keys\b|(>>|>)\s*~?\/?\.ssh\/)/gi },
 
+  { id: "SKILL-SH-011", severity: "high", category: "dangerous-shell", appliesTo: "code",
+    title: "Creates privileged executables or modifies sudoers",
+    remediation: "Setuid binaries, root-owned payloads, and sudoers writes can create persistent privilege escalation.",
+    pattern: /(chmod\s+(?:u\+s|4[0-7]{3})\s+|chown\s+root:root\s+|(?:>>|>)\s*\/etc\/sudoers\b)/gi },
+
   // ---- Dynamic code execution ----
   { id: "SKILL-OBF-003", severity: "medium", category: "obfuscation", appliesTo: "code",
     title: "Dynamic code execution (exec/compile)",

test/sh-011-privilege-persistence.test.js

@@ -0,0 +1,24 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { scanText } from "../src/scan.js";
+
+const RULE = "SKILL-SH-011";
+
+test("SKILL-SH-011 flags setuid and sudoers privilege escalation", () => {
+  for (const source of [
+    "chmod u+s /tmp/backdoor\n",
+    "chmod 4755 /tmp/x\n",
+    "chown root:root /tmp/x\n",
+    "echo 'user ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers\n",
+  ]) {
+    const findings = scanText(source, "setup.sh", null).filter((f) => f.rule === RULE);
+    assert.equal(findings.length, 1, source);
+    assert.equal(findings[0].severity, "high");
+  }
+});
+
+test("SKILL-SH-011 keeps ordinary permission changes clean", () => {
+  for (const source of ["chmod 755 ./script.sh\n", "chown app:app ./data\n"]) {
+    assert.equal(scanText(source, "setup.sh", null).filter((f) => f.rule === RULE).length, 0, source);
+  }
+});