refactor: Remote code execution via MongoDB BSON parser through prototype pollution; fixes security vulnerability [GHSA-prm5-8g2m-24gg](https://github.com/parse-community/parse-server/security/advisories/GHSA-prm5-8g2m-24gg) (#8297)

spec/vulnerabilities.spec.js

@@ -279,6 +279,44 @@ describe('Vulnerabilities', () => {
       expect(text.code).toBe(Parse.Error.INVALID_KEY_NAME);
       expect(text.error).toBe('Prohibited keyword in request data: {"value":"aValue[123]*"}.');
     });
+
+    it('denies BSON type code data in file metadata', async () => {
+      const str = 'Hello World!';
+      const data = [];
+      for (let i = 0; i < str.length; i++) {
+        data.push(str.charCodeAt(i));
+      }
+      const file = new Parse.File('hello.txt', data, 'text/plain');
+      file.addMetadata('obj', {
+        _bsontype: 'Code',
+        code: 'delete Object.prototype.evalFunctions',
+      });
+      await expectAsync(file.save()).toBeRejectedWith(
+        new Parse.Error(
+          Parse.Error.INVALID_KEY_NAME,
+          `Prohibited keyword in request data: {"key":"_bsontype","value":"Code"}.`
+        )
+      );
+    });
+
+    it('denies BSON type code data in file tags', async () => {
+      const str = 'Hello World!';
+      const data = [];
+      for (let i = 0; i < str.length; i++) {
+        data.push(str.charCodeAt(i));
+      }
+      const file = new Parse.File('hello.txt', data, 'text/plain');
+      file.addTag('obj', {
+        _bsontype: 'Code',
+        code: 'delete Object.prototype.evalFunctions',
+      });
+      await expectAsync(file.save()).toBeRejectedWith(
+        new Parse.Error(
+          Parse.Error.INVALID_KEY_NAME,
+          `Prohibited keyword in request data: {"key":"_bsontype","value":"Code"}.`
+        )
+      );
+    });
   });
 
   describe('Ignore non-matches', () => {

src/Routers/FilesRouter.js

@@ -7,6 +7,7 @@ import mime from 'mime';
 import logger from '../logger';
 const triggers = require('../triggers');
 const http = require('http');
+const Utils = require('../Utils');
 
 const downloadFileFromURI = uri => {
   return new Promise((res, rej) => {
@@ -140,6 +141,23 @@ export class FilesRouter {
     const base64 = req.body.toString('base64');
     const file = new Parse.File(filename, { base64 }, contentType);
     const { metadata = {}, tags = {} } = req.fileData || {};
+    if (req.config && req.config.requestKeywordDenylist) {
+      // Scan request data for denied keywords
+      for (const keyword of req.config.requestKeywordDenylist) {
+        const match =
+          Utils.objectContainsKeyValue(metadata, keyword.key, keyword.value) ||
+          Utils.objectContainsKeyValue(tags, keyword.key, keyword.value);
+        if (match) {
+          next(
+            new Parse.Error(
+              Parse.Error.INVALID_KEY_NAME,
+              `Prohibited keyword in request data: ${JSON.stringify(keyword)}.`
+            )
+          );
+          return;
+        }
+      }
+    }
     file.setTags(tags);
     file.setMetadata(metadata);
     const fileSize = Buffer.byteLength(req.body);