Merge pull request #3 from superindustries/feature/js-interpreter

feat: add basic sandbox JS execution based on VM2

package.json

@@ -38,5 +38,8 @@
     "rimraf": "^3.0.2",
     "ts-jest": "^26.1.0",
     "typescript": "^3.9.2"
+  },
+  "dependencies": {
+    "vm2": "^3.9.2"
   }
 }

src/client/interpreter/Sandbox.test.ts

@@ -0,0 +1,60 @@
+import { Sandbox } from "./Sandbox";
+
+describe("sandbox", () => {
+  let sandbox!: Sandbox;
+
+  beforeEach(() => {
+    process.env.SECRET = "MuchSecret";
+    sandbox = new Sandbox();
+  });
+
+  it("prevents string masking attackt", () => {
+    const js = `   
+    // Let x be any value not in
+    // (null, undefined, Object.create(null)).
+    var x = {},
+      // If the attacker can control three strings
+      a = "constructor",
+      b = "constructor",
+      s = "process.env.SECRET = 'overwrite'";
+    // and trick code into doing two property lookups
+    // they control, a call with a string they control,
+    // and one more call with any argument
+    x[a][b](s)();
+    // then they can cause any side-effect achievable
+    // solely via objects reachable from the global scope.
+    // This includes full access to any exported module APIs,
+    // all declarations in the current module, and access
+    // to builtin modules like child_process, fs, and net.
+    `;
+
+    expect(() => sandbox.evalJS(js)).toThrowError();
+    expect(process.env.SECRET).toEqual("MuchSecret");
+  });
+
+  it("prevents primodial types pollution", () => {
+    const js = `
+    Array.prototype.toString = () => {
+      console.log("I have been called!!!!");
+      return "Modified!!!!";
+    };`;
+    sandbox.evalJS(js);
+    expect([1, 2, 3].toString()).toEqual("1,2,3");
+  });
+
+  it("prevents quitting the process", () => {
+    const js = `process.exit();`;
+    expect(() => sandbox.evalJS(js)).toThrowError();
+  });
+
+  describe("Halting problem (Stalling the event loop)", () => {
+    it("while(true)", () => {
+      expect(() => sandbox.evalJS(`while(true){1+1}`)).toThrowError(/Script execution timed out/);
+
+    });
+
+    it("prevents using async", () => {
+      expect(() => sandbox.evalJS(`new Promise.resolve(5)`)).toThrowError(/Promise/);
+    });
+  });
+});

src/client/interpreter/Sandbox.ts

@@ -0,0 +1,14 @@
+import { VM } from "vm2";
+
+export class Sandbox {
+  evalJS = (js: string): unknown => {
+    const vm = new VM({
+      sandbox: {},
+      wasm: false,
+      eval: false,
+      timeout: 100,
+    });
+
+    return vm.run(`'use strict'; ${js}`);
+  };
+}

yarn.lock

@@ -6571,6 +6571,11 @@ vlq@^0.2.2:
   resolved "https://registry.yarnpkg.com/vlq/-/vlq-0.2.3.tgz#8f3e4328cf63b1540c0d67e1b2778386f8975b26"
   integrity sha512-DRibZL6DsNhIgYQ+wNdWDL2SL3bKPlVrRiBqV5yuMm++op8W4kGFtaQfCs4KEJn0wBZcHVHJ3eoywX8983k1ow==
 
+vm2@^3.9.2:
+  version "3.9.2"
+  resolved "https://registry.yarnpkg.com/vm2/-/vm2-3.9.2.tgz#a4085d2d88a808a1b3c06d5478c2db3222a9cc30"
+  integrity sha512-nzyFmHdy2FMg7mYraRytc2jr4QBaUY3TEGe3q3bK8EgS9WC98wxn2jrPxS/ruWm+JGzrEIIeufKweQzVoQEd+Q==
+
 w3c-hr-time@^1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/w3c-hr-time/-/w3c-hr-time-1.0.2.tgz#0a89cdf5cc15822df9c360543676963e0cc308cd"