3 Potential Security Issues in Terraform and How to Address Them

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In recent years, Terraform has become one of the preferred tools for infrastructure-as-code (IaC) management. The rise of Terraform can largely be attributed to its use of declarative language, multi-cloud support, immutability, modularity, reusability, and ability to integrate with a variety of other tools. Also, its large user base entails a bigger active community of users and developers who share troubleshooting insights, best practices, and community-maintained modules.

However, like any product, Terraform has its weaknesses. There may have been no high-profile news about cyber attacks targeting Terraform, but that does not mean there are no potential security issues. Experienced Terraform users are aware of the potential problems, which is why they have requested HashiCorp, the developer of Terraform, for new testing and quality analysis features to improve efficiency and security.

Here are three security issues Terraform users should be aware of. These concerns tend to be overlooked, especially among organizations that are new to using Terraform or implementing IaC in general.

Exposing Sensitive Data Through State Files

One of the most important details pointed out in Terraform tutorials is the critical nature of state files. These documents can contain sensitive details such as login credentials, access keys, secrets or passwords, encryption keys, and security group rules. These details can be compromised if the state file is assigned to an unsecured storage.

By default, state files are stored in a local backend, which may not be properly protected. It is important to make sure that state files are adequately secured, and it may be necessary to use remote backend options like Terraform Cloud and Azure Storage.

Aside from securely storing state files, there should also be regulated access to them. Terraform provides access controls to ensure that only those with proper permissions or authority can read or modify state files and the critical infrastructure information contained in them. These access controls should be carefully configured.

Additionally, Terraform provides the option to encrypt sensitive information or use encrypted storage solutions for added protection. It also has a “state locking” feature that stops simultaneous modifications to state files, which helps prevent instances of data corruption due to process conflicts.

The accidental leakage of Terraform state files can happen especially in collaborative environments where there are multiple users involved. This leakage is a vulnerability that can allow attackers to manipulate configurations, causing infrastructure failures or unwanted behavior that leads to more problems. It is advisable to implement measures such as checksum verification to evaluate the integrity of state files and prevent changes that cause deviations from the desired infrastructure state.

Poor Management of Credentials

Credentials are necessary for Terraform to securely interact with cloud providers and crucial services. Terraform has a built-in credential management system, but it may not be enough to rely on default settings. For one, this credential management system stores details in plain text within the configuration or state files. If the configuration files are not properly secured, the stored credentials will most certainly be compromised.

Terraform’s built-in credential management module does not support any advanced security controls. It does not come with encryption, access control, and secure storage capabilities that come with third-party solutions. Also, credentials are handled manually within the configuration or state files. This exposes sensitive information to potential adverse consequences due to human error. Configuration files may be shared inadvertently with outside parties, which means exposing credentials to potential attackers.

Also, configurations may be shared on source code repositories, which can similarly reveal credentials to outsiders.

Moreover, Terraform’s credential management system does not come with automated credential rotation, expiration, and revocation mechanisms. Everything has to be manually changed or updated to reflect the intended changes. The manual inputting of data creates opportunities for errors or insider attacks to expose credentials.

It helps to use a third-party credential management solution to address these challenges, but this is not a necessity. Organizations can establish more rigorous processes and accountability measures to secure credentials adequately. The state or configuration files can be securely stored to prevent data compromises.

The process of manually changing credentials stored in the state files can also be secured by having a system that requires direct supervision over any credential information change.

Dependency Vulnerabilities

Security issues can also rear their heads when using Terraform modules, provider plugins, and other components, as these may contain vulnerabilities. Often, these dependency vulnerabilities can be traced to third-party libraries, runtime environments, or infrastructure services that have been intentionally laced with malicious scripts by cybercriminals, or components that have vulnerabilities that can be exploited by hackers. To avoid these security issues, it is important to undertake regular vulnerability scanning, dependency versioning, dependency auditing, dependency locking, as well as vendor security reviews.

Vulnerability scanning is part of the usual IaC code review routine, but it may be necessary to emphasize the thorough scanning of dependencies to ensure that vulnerabilities and other security issues are properly addressed. Savvy security teams know how to automate vulnerability scanning tests.

Dependency versioning refers to the management of the versions of dependencies used to make sure that they have no defects and that they are secure. The available versions should be scrutinized first to make sure they are safe and functional. The exact versions or ranges of versions that are deemed safe have to be specified in the configuration.

Dependency auditing involves meticulously evaluating third-party dependencies employed in Terraform modules and provider plugins. This basically means testing the safety, reliability, and reliability of components. It is important to ascertain that they come from reputable sources and that they are well-maintained.

Dependency locking refers to implementing mechanisms or tools to stop unexpected updates or changes from being applied to dependencies. Unlike software updates, the best practice when it comes to dependencies is to not automatically update to the latest versions. Teams should only switch to new iterations of dependencies following assessments of their security and reliability.

Moreover, it is a must to conduct vendor security reviews. This is usually undertaken in collaboration with Terraform module maintainers, the developers of provider plugins, and third-party sources of dependencies or components. It is advisable to verify the security practices of vendors and third-party sources, their processes in managing vulnerabilities, and the security controls they implement.

The Bottom Line

Terraform is by no means notorious for security issues. However, there’s no harm in being cautious, especially for those who are not yet familiar with infrastructure-as-code best practices. New users of the Terraform IaC provisioning and management system are bound to encounter issues or commit mistakes as they get more acquainted with it. Mastering Terraform security cannot be a hasty endeavor. A good way to get started is to pay attention to the sensitive data contained in state files, the management of credentials, and dependency vulnerabilities.

Jennifer Thomas
Jennifer Thomas is the Co-founder and Chief Business Development Officer at Cybers Guards. Prior to that, She was responsible for leading its Cyber Security Practice and Cyber Security Operations Center, which provided managed security services.