Securing a Containerized Instance of MongoDB

on Mar 9, 2017

Securing MongoDBMongoDB, the popular open source NoSQL database, has been in the news a lot recently—and not for reasons that are good for MongoDB admins. Early this year, reports began appearing of MongoDB databases being “taken hostage” by attackers who delete all of the data stored inside the databases, then demand ransoms to restore it.

Security is always important, no matter which type of database you’re using. But the recent spate of MongoDB attacks makes it especially crucial to secure any MongoDB databases that you may use as part of your container stack.

This article explains what you need to know to keep MongoDB secure when it is running as a container. We’ll go over how to close the vulnerability behind the recent ransomware attacks using a MongoDB container while the container is running—as well as how to modify a MongoDB Dockerfile to change the default behavior permanently.

Why the Ransomware Happened: MongoDB’s Default Security Configuration

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The ransomware attacks against MongoDB weren’t enabled by a flaw inherent in MongoDB itself, per se, but rather by some weaknesses that result from default configuration parameters in an out-of-the-box installation of MongoDB.

By default, MongoDB databases, unlike most other popular database platforms, don’t require login credentials. That means anyone can log into the database and start modifying or removing data.

Securing a MongoDB Container
In order to mitigate that vulnerability and run a secure containerized instance of MongoDB, follow the steps below.

Start a MongoDB instance
First of all, start a MongoDB instance in Docker using the most up-to-date image available. Since Docker uses the most recent image by default, a simple command like this will start a MongoDB instance based on an up-to-date image:

docker run --name mongo-database -d mongo

Create a secure MongoDB account
Before disabling password-less authentication to MongoDB, we need to create an account that we can use to log in after we change the default settings.

To do this, first log into the MongoDB container with:

docker exec -it mongo-database bash

Then, from inside the container, log into the MongoDB admin interface:

mongo

Now, enter this stanza of code and press Enter:

use admin
db.createUser(
{
user: "db_user",
pwd: "your_super_secure_password",
roles: [ { role: "userAdminAnyDatabase", db: "admin" } ]
}
)

This creates a MongoDB user with username db_user and password your_super_secure_password

(Feel free to change this, of course, to something more secure!)

The user has admin privileges.

Changing default behavior in Dockerfile
If you want to make the MongoDB process start with authentication required by default all of the time, you can do so by editing the Dockerfile used to build the container.

To do this locally, we’ll first pull the MongoDB Dockerfile from GitHub with:

git clone https://github.com/dockerfile/mongodb

Now, cd into the mongodb directory that Git just created and open the Dockerfile inside using your favorite text editor. Look for the following section of the Dockerfile:

# Define default command.
CMD ["mongod"]

Change this to:

# Define default command.
CMD ["mongod --auth"]

This way, when mongodb is called when the container starts, it will run with the –auth flag by default.

Conclusion

If you follow the steps above, you’ll be able to run MongoDB as a Docker container without becoming one of the tens of thousands of admins whose MongoDB databases were wiped out and held for ransom by attackers. And there really is not much to it, other than being aware of the vulnerabilities inherent in a default MongoDB installation and the steps for resolving them.

Chris Riley (@HoardingInfo) is a technologist who has spent 12 years helping organizations transition from traditional development practices to a modern set of culture, processes and tooling. In addition to being a research analyst, he is an O’Reilly author, regular speaker, and subject matter expert in the areas of DevOps strategy and culture. Chris believes the biggest challenges faced in the tech market are not tools, but rather people and planning.

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