Unfortunately, the scariest breach is the one you didn't cause. You can do nearly everything right, MFA everywhere, tested backups, and patches applied on schedule, and still wake up to an incident that started in a vendor's environment, a partner's email account, or a piece of software somebody else built.
That's third-party risk, and it's not a niche concern anymore. It's how a large and growing share of breaches actually happen.
While you may be aware of what could happen in your own environment and how to fix it when something goes wrong, you can't patch a vendor. You can't run a restore test on your accountant's inbox. But you can absolutely reduce the blast radius, and this post is about how.
In ISC2's 2025 global survey, 28% of cybersecurity professionals said their organization experienced a cybersecurity incident that originated from a third-party vendor or supplier within the past two years. That’s not an insignificant number.
Most of the time, these incidents do not arrive looking like attacks. Here are four common paths we see that third-party incidents take to impact organizations:
Your vendor has legitimate access to your systems. That's the whole point of the relationship. A compromised vendor can create a pathway into their customer's environment when attackers obtain usable credentials, sessions, or access to trusted integrations. Because that activity may initially resemble authorized access, detecting the compromise can be more challenging.
Supply chain attacks target the software supply itself. It could be a malicious update, compromised dependency, or backdoor slipped into a product you already trust. When that happens, installing the update is the attack. Your patching discipline, which is normally a strength, works against you. You deployed it promptly, like you were supposed to.
Even vendors with no technical access to your systems hold your data, whether it’s payroll providers, benefits administrators, marketing platforms, or file-sharing tools. When they're breached, your data leaks anyway. The breach is theirs, but the notification letters, the credit monitoring, and the client conversations are yours.
Business email compromise often travels through partners. A fraudster who compromises a vendor's mailbox can send payment-change requests that come from a real address you actually do business with, which is why "check the sender" advice stopped being sufficient years ago.
You don't need an entire GRC platform to start protecting your organization. You can put yourself in a better position by thinking about the following:
Make a list of the people who have access to your systems, your data, and your financials. This could be an old payroll tool, a former IT provider, or a marketing contractor with a login from a few years ago.
Ask who still needs access. Find out what vendors are being used now and what contracts were discontinued. Then, create a process to keep this information current. Former vendors with active credentials are one of the most common findings in any access review.
Ask how they'd tell you. If your vendor got breached tonight, how and when would you find out? If you aren’t sure, we suggest putting breach notification timelines in the contract at the next renewal. This way, you get notified right away and can start remediating, if necessary.
Check the MFA question. Does every vendor with remote access to your environment require MFA? If they don’t, it’s time to reinforce it.
Rehearse the scenario. If your bookkeeper relies on a platform that was breached and your data was in it, what would you do in the first 24 hours? Do you have a plan for these situations? If not, this is your sign to create one.
None of this requires distrusting your vendors. The ISC2 survey highlighted the real issue here. It's not that vendors are malicious. It's that "trust but can't verify" is not a security strategy. Verification is necessary to have a strong cybersecurity posture.
Fundamentally, third-party risk is a visibility problem, and visibility is what a managed security relationship buys. Knowing what's on your network, who's accessing it, and what normal behavior looks like is the foundation for spotting the abnormal, whether it originates inside your walls or walks in through a vendor's connection.
It's the model NetCov runs on: a 24/7/365 Security Operations Center that ingests alerts and telemetry from across your environment, including the systems your vendors touch, and investigates in real time. When a trusted login suddenly behaves like an untrusted one, someone is watching, and someone acts.
On the IT side, vendor access reviews, offboarding discipline, and MFA enforcement across every external connection are exactly the kind of unglamorous, ongoing work a managed IT partner does as a matter of routine. This way, it stops depending on someone remembering.
We understand that figuring out where your risks are can be overwhelming. That’s why we offer a cybersecurity assessment to evaluate the effectiveness of your existing security controls. The outcome is prioritized, actionable recommendations and a comprehensive report that’s digestible. Contact us today for the assessment.
What is third-party risk in cybersecurity?
Third-party risk is the security exposure your business takes on through vendors, partners, and service providers. It involves anyone outside your organization who has access to your systems, data, or money. If a vendor gets breached, attackers can use that trusted access to reach you, or your data can leak from their environment even though your own defenses held up.
How common are third-party breaches?
Unfortunately, they are more common than most businesses realize. ISC2's 2025 supply chain survey found that 28% of organizations experienced a cybersecurity incident originating from a third-party vendor within the past two years.
How do attackers use vendors to reach other companies?
The most common path is the trusted connection. A vendor has legitimate access to your systems, so when attackers compromise the vendor, they log in with credentials that are supposed to have access. Other common paths include compromised software updates, data you've handed to vendors with no technical access, and business email compromise that travels through a partner's mailbox.
What should we require from vendors with access to our systems?
You should require vendors to have multi-factor authentication on any remote access, documented incident response and breach notification procedures with specific timelines, and evidence of security controls, such as a SOC 2 report or compliance with a recognized framework.
How does NetCov help protect organizations against third-party breaches?
NetCov helps protect organizations against third-party breaches with our 24/7/365 Security Operations Center that ingests alerts and telemetry from across their environment, including the systems vendors touch, and investigates in real time. Our security operations combine machine learning, real-time monitoring, and expert analysis to detect and stop threats before they cause damage.