Overview

A potential memory disclosure vulnerability exists in sequelize versions prior to 3.17.2. A field of type DataTypes.BLOB can be used to expose sensitive information such as code, runtime memory and user data into the database.

Details

sequelize uses the Buffer type to represent DataTypes.BLOB. Initializing a Buffer with integer N creates a Buffer of length N with non zero-ed out memory. Example:

var x = new Buffer(100); // uninitialized Buffer of length 100
// vs
var x = new Buffer('100'); // initialized Buffer with value of '100'

Initializing a BLOB field in such manner will dump uninitialized memory into the database. The patch wraps Buffer field initialization in sequelize by converting a number value N to a string, initializing the Buffer with N in its ascii form.

Proof of concept

var Sequelize = require('sequelize');
var sequelize = new Sequelize('pastebin', null, null,
    { host: '127.0.0.1', dialect: 'postgres', });

var Task = sequelize.define('Pastebin', {
    title: Sequelize.STRING,
    content: Sequelize.BLOB,
  });

Task.create({
  title: 'title',
  content: 100,
}).then(function (task) {
  console.log(task.title);
  console.log(task.content); // will print out 100 bytes of previously used memory
});

Remediation

Upgrade sequelize to version >= 3.17.3

References

• https://github.com/sequelize/sequelize/blob/master/changelog.md#3172
• https://github.com/sequelize/sequelize/commit/cbfaa4f0a135cfc55874c9bfc39ead2d85c417e9
• https://github.com/ChALkeR/notes/blob/master/Lets-fix-Buffer-API.md#previous-materials
• https://github.com/ChALkeR/notes/blob/master/Buffer-knows-everything.md

Snyk patch available for versions:

• <3.17.2 >3.16.0
  View patch
• <=3.16.0 >3.13.0
  View patch