With cybersecurity breaches increasing more and more each year, it seems that no security strategy is absolutely perfect. In fact, the constant evolution of technology pretty much guarantees that no strategy will be 100% breach-proof. Securing online data is just out of your control… Or is it?

Many companies don’t realize that most breaches happen from a third-party source. While your security strategy might be near perfect, attackers will find a way in through an unprotected vendor with access to your network. No matter how tight your cybersecurity is, it all comes down to who you give access to, and you’re only as protected as your most vulnerable provider.

So keep your enemies close and your friends closer, because the secret killer of your cybersecurity strategy is your third-party relationships. Outsourced providers, vendors, contractors, hosting services—the list of relationships your company has with external providers could be endless, and many of them have unrestricted access to your network.

Here are a few ways to prevent a third-party breach:

Create a written agreement

Cybersecurity expectations are rarely included in a service agreement, so make sure you know the security you require of your providers and put it in writing. These requirements could be anything involving the security of your network, such as who has access to your data, your providers’ security controls, or how well their security is managed. No request is too big when it comes to protecting your information.

Do a complete and thorough third-party inventory

You should always know who has access to your network, no matter how little or how much they do for you. Keep a list of who your providers are, what they have access to and details on the services they provide. This keeps you aware of all access points coming into your network, ensuring complete knowledge of potential risks and holes that hackers commonly search for to get into places they shouldn’t.

Manage your relationships

Third-party providers can be reluctant to share security information with their clients, and understandably so. They need to be equally protective of their data. But times are changing, and companies need to be more aware of how their outsource relationships can affect their own security. Your service providers can have the best of intentions to keep themselves and their clients safe, but one crack in their system can make your company vulnerable.

Don’t be apprehensive about managing the access and security controls of your third-party relationships. The new reality is that transparency is needed across the board. So monitor your external relationships, manage their access to your information, and rest assured you’re doing everything to prevent a breach in your system.