feat: zipbomb detection using static analysis

package.json

@@ -18,6 +18,7 @@
     "standard": "^11.0.1"
   },
   "dependencies": {
+    "@ronomon/pure": "^1.0.4",
     "amazon-s3-uri": "0.0.3",
     "aws-sdk": "^2.300.0",
     "axios": "^0.18.0",

src/common/helper.js

@@ -13,6 +13,7 @@ const m2mAuth = require('tc-core-library-js').auth.m2m
 const m2m = m2mAuth(_.pick(config, ['AUTH0_URL', 'AUTH0_AUDIENCE', 'TOKEN_CACHE_TIME', 'AUTH0_PROXY_SERVER_URL']))
 const AWS = require('aws-sdk')
 const AmazonS3URI = require('amazon-s3-uri')
+const pure = require("@ronomon/pure");
 
 AWS.config.region = config.get('aws.REGION')
 const s3 = new AWS.S3()
@@ -39,11 +40,26 @@ function * downloadFile (fileURL) {
   }
 }
 
-function * scanWithClamAV (fileURL) {
-  // Download file from URL
-  const downloadedFile = yield downloadFile(fileURL)
+/**
+ * check if the file is a zipbomb
+ *
+ * @param {string} fileBuffer the file buffer
+ * @returns
+ */
+ function isZipBomb(fileBuffer) {
+  const error = pure.zip(fileBuffer, 0);
+
+  // we only care about zip bombs
+  if (error.code === "PURE_E_OK" || error.code.indexOf("ZIP_BOMB") === -1) {
+    return [false];
+  } else {
+    return [true, error.code, error.message];
+  }
+}
+
+function * scanWithClamAV (file) {
   // Scan
-  const fileStream = streamifier.createReadStream(downloadedFile)
+  const fileStream = streamifier.createReadStream(file)
   return new Promise((resolve, reject) => {
     clamavScanner.scan(fileStream, (scanErr, object, malicious) => {
       if (scanErr) {
@@ -85,6 +101,7 @@ function * postToBusAPI (reqBody) {
 }
 
 module.exports = {
+  isZipBomb,
   scanWithClamAV,
   postToBusAPI
 }

src/services/ProcessorService.js

@@ -11,11 +11,23 @@ const helper = require('../common/helper')
  * @param {Object} message the message
  */
 function * processScan (message) {
-  // Scan the file using ClamAV
-  const isInfected = yield helper.scanWithClamAV(message.payload.url)
-  // Update Scanning results
   message.timestamp = (new Date()).toISOString()
   message.payload.status = 'scanned'
+
+  const downloadedFile = yield helper.downloadFile(message.payload.url);
+
+  // Scan the file using ClamAV
+  const [isZipBomb, errorCode, errorMessage] = helper.isZipBomb(downloadedFile);
+  if (isZipBomb) {
+    message.isInfected = true;
+    logger.warn(`File at ${message.payload.url} is a ZipBomb. ${errorCode}: ${errorMessage}`);
+    yield helper.postToBusAPI(message)
+    return message;
+  }
+
+  const isInfected = yield helper.scanWithClamAV(downloadedFile)
+
+  // Update Scanning results
   message.payload.isInfected = isInfected
 
   yield helper.postToBusAPI(message)