test(shell-scan): probe opaque mutation closure

packages/shell-scan/test/mutation.test.ts

@@ -0,0 +1,120 @@
+import { describe, expect, test } from "bun:test"
+import { ShellScan } from "../src/index.js"
+
+type Mutation = {
+  name: string
+  apply: (source: string) => string
+}
+
+const head = (source: string, mutate: (value: string) => string) =>
+  source.replace(/^\S+/, (value) => mutate(value))
+
+const contexts: Mutation[] = [
+  { name: "leading spaces", apply: (source) => `  ${source}` },
+  { name: "leading tab", apply: (source) => `\t${source}` },
+  { name: "semicolon prefix", apply: (source) => `printf safe; ${source}` },
+  { name: "and prefix", apply: (source) => `printf safe && ${source}` },
+  { name: "or suffix", apply: (source) => `${source} || printf safe` },
+  { name: "newline suffix", apply: (source) => `${source}\nprintf safe` },
+]
+
+const bashSeeds = [
+  ["evaluator", `eval 'printf pwn'`],
+  ["shell", `bash -c 'printf pwn'`],
+  ["wrapper", "env MODE=test printf pwn"],
+  ["dynamic builtin", "alias harmless='printf pwn'"],
+  ["find callback", "find . -exec printf pwn ;"],
+  ["awk source", `awk 'BEGIN { system("printf pwn") }'`],
+  ["git alias", `git -c alias.pwn='!printf pwn' pwn`],
+  ["python source", `python3 -c 'print(1)'`],
+  ["node source", `node --eval='process.exit()'`],
+] as const
+
+describe("ShellScan opaque mutation closure", () => {
+  const headMutations: Mutation[] = [
+    { name: "absolute path", apply: (source) => head(source, (value) => `/usr/bin/${value}`) },
+    { name: "relative path", apply: (source) => head(source, (value) => `./${value}`) },
+    { name: "single-quoted head", apply: (source) => head(source, (value) => `'${value}'`) },
+    { name: "double-quoted head", apply: (source) => head(source, (value) => `"${value}"`) },
+    {
+      name: "escaped head",
+      apply: (source) => head(source, (value) => `${value[0]}\\${value.slice(1)}`),
+    },
+  ]
+
+  for (const [seed, source] of bashSeeds) {
+    for (const mutation of [...headMutations, ...contexts]) {
+      test(`${seed} remains opaque after ${mutation.name}`, () => {
+        expect(ShellScan.scan(mutation.apply(source)).kind).toBe("opaque")
+      })
+    }
+  }
+
+  test.each([
+    ["python short option cluster", `python3 -Ic'print(1)'`],
+    ["perl short option cluster", `perl -we'print 1'`],
+    ["ruby short option cluster", `ruby -we'puts 1'`],
+    ["node attached long option", `node --eval='process.exit()'`],
+  ])("attached source flag remains opaque: %s", (_name, source) => {
+    expect(ShellScan.scan(source).kind).toBe("opaque")
+  })
+})
+
+const powerShellContexts: Mutation[] = [
+  { name: "leading spaces", apply: (source) => `  ${source}` },
+  { name: "leading tab", apply: (source) => `\t${source}` },
+  { name: "semicolon prefix", apply: (source) => `Write-Output safe; ${source}` },
+  { name: "pipeline prefix", apply: (source) => `Write-Output safe | ${source}` },
+  { name: "newline suffix", apply: (source) => `${source}\nWrite-Output safe` },
+]
+
+const powerShellSeeds = [
+  ["expression evaluator", `Invoke-Expression 'Write-Output pwn'`],
+  ["expression alias", `iex 'Write-Output pwn'`],
+  ["process launcher", "Start-Process pwsh -ArgumentList -Command,pwn"],
+  ["process alias", "saps pwsh -ArgumentList -Command,pwn"],
+  ["module importer", "Import-Module ./evil.psm1"],
+  ["module alias", "ipmo ./evil.psm1"],
+  ["alias mutation", "Set-Alias harmless Remove-Item"],
+  ["alias mutation alias", "sal harmless Remove-Item"],
+  ["shell", "pwsh -Command Write-Output,pwn"],
+  ["script", "./evil.ps1 -Force"],
+] as const
+
+describe("ShellScan PowerShell opaque mutation closure", () => {
+  for (const [seed, source] of powerShellSeeds) {
+    const mutations: Mutation[] = [
+      { name: "case change", apply: (value) => head(value, (name) => name.toUpperCase()) },
+      { name: "single-quoted head", apply: (value) => head(value, (name) => `'${name}'`) },
+      { name: "double-quoted head", apply: (value) => head(value, (name) => `"${name}"`) },
+      {
+        name: "escaped head",
+        apply: (value) => head(value, (name) => `${name[0]}\`${name.slice(1)}`),
+      },
+      ...powerShellContexts,
+    ]
+
+    for (const mutation of mutations) {
+      test(`${seed} remains opaque after ${mutation.name}`, () => {
+        expect(ShellScan.scanPowerShell(mutation.apply(source)).kind).toBe("opaque")
+      })
+    }
+  }
+
+  test.each([
+    ["evaluator", `Microsoft.PowerShell.Utility\\Invoke-Expression 'Write-Output pwn'`],
+    ["process launcher", "Microsoft.PowerShell.Management\\Start-Process pwsh"],
+    ["module importer", "Microsoft.PowerShell.Core\\Import-Module ./evil.psm1"],
+    ["alias mutation", "Microsoft.PowerShell.Utility\\Set-Alias harmless Remove-Item"],
+  ])("module-qualified command remains opaque: %s", (_name, source) => {
+    expect(ShellScan.scanPowerShell(source).kind).toBe("opaque")
+  })
+
+  test.each([
+    ["powershell path", `C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe -Command pwn`],
+    ["cmd path", `C:\\Windows\\System32\\cmd.exe /c pwn`],
+    ["script path", `C:\\work\\evil.ps1 -Force`],
+  ])("path-qualified command remains opaque: %s", (_name, source) => {
+    expect(ShellScan.scanPowerShell(source).kind).toBe("opaque")
+  })
+})