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Interconnection Security Agreement (ISA)

An Interconnection Security Agreement (ISA) is a formal contract between organizations that defines the security requirements, terms, and technical parameters governing how their IT systems will be connected. It ensures both parties align on security measures before any cross-organizational network link is established.

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About this video

Connecting an organization's IT infrastructure to that of another company introduces a new and significant attack surface, since each party inherits exposure to the other's vulnerabilities. An Interconnection Security Agreement (ISA) is a formal, legally binding contract designed to manage this risk by establishing clear, agreed-upon terms before any cross-organizational network connection is made. It documents the technical details of how systems will interconnect, the security controls both parties must maintain, and the timeframes and conditions governing the relationship. Because no two organizations operate identical IT environments or cybersecurity programs, differences in infrastructure, policy, and risk posture can create friction and exposure when systems are joined. An ISA brings both parties to a common standard, ensuring that security expectations are explicit and enforceable rather than assumed. The agreement functions as a governance document that both organizations review and sign, much like any other legal contract. ISAs are relevant across industries and are referenced in numerous compliance frameworks as a required or strongly recommended control. A practical example is the U.S. Department of Agriculture's ISA for third parties seeking access to its crop information system — a documented agreement that includes technical diagrams of the connection architecture and requires a signature from the connecting party. Any organization that needs to establish a business-to-business IT connection should have an ISA in place to protect both parties and formalize the terms of that integration.

What you'll learn

What's covered

Interconnection Security Agreement (ISA)

Aligned to

NIST 800-53
CA-3 Information Exchange
CompTIA Security+
5.3 Explain the processes associated with third-party risk assessment and management.
ISC2 CISSP
1.9 Understand and apply risk management concepts
NIST CSF
GV.SC-05 Requirements to address cybersecurity risks in supply chains are established, prioritized, and integrated into contracts and other types of agreements with suppliers and other relevant third parties.

Key terms

Interconnection Security Agreement
ISA
A formal agreement between two organizations that specifies the technical and security requirements for connecting their IT systems, defining each party's responsibilities for protecting shared data in transit.
Vulnerability
A weakness in a system, application, or process that can be exploited by a threat actor.
Security Policy
A formal document that defines an organization's security goals, rules, and responsibilities.
Risk
The potential for loss or harm resulting from a threat exploiting a vulnerability.

Topics

Interconnection Security Agreement Security Agreements Cross Organizational Security Network Security Governance Risk Compliance Security Policy

Transcript

There are times when we want to interconnect our IT systems with another company's IT systems. The problem is that opens up our network and our infrastructure to all the vulnerabilities that that other infrastructure has. And so we want to make sure that there's some agreement on what that connection looks like and how we're going to establish it. That's what an interconnection security agreement, or an ISA, does.

No two companies operate the same way. Neither do their IT departments, their cyber security program, or their IT infrastructures. And there are times when we want to connect them together, but because there's so much differences we want to avoid it as much as possible. But sometimes it just makes sense, that there's a lot of advantages and a lot to be gained by interconnecting the two companies together.

And so in that case we need to make sure that we're operating off the same page, that we are going to implement similar security measures, that we know how the systems are going to interconnect, that we know things like the time frame in which we're going to interconnect those. And so we write that all down into an agreement, and we agree upon this set of parameters. We call this an interconnection security agreement, or ISA.

Who should establish an ISA

So who should establish an ISA? Well, I have had customers that had that requirement. I've also seen it in frameworks. Really, anytime that you're interconnecting business IT systems you should have some sort of ISA in place.

An example

Here's an example of an interconnection security agreement. This is one that the US Department of Agriculture has, and this is if you want to connect to their crop information system. This is something that if somebody wants to connect to the system, they're going to have to agree to these terms, and then they will sign this. You can see that it's just a legal contract that both parties would then sign, and how that interconnection is going to happen.

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