The Silent Breach: Why Third Parties Are Cybersecurity’s Greatest Hidden Threat

Bylin: Jeffrey Wheatman, Senior Vice President, Cyber Risk Strategist

Cybersecurity teams are always on alert for the next attack, but the most dangerous threats are often the ones no one sees coming. 

Silent breaches — often unnoticed vulnerabilities within third-party networks — are becoming one of the most pervasive cybersecurity challenges. While the rise of interconnected IT ecosystems has fueled efficiency, it’s also created entry points for attackers that often go undetected until it’s too late.

As organizations rely more on third-party suppliers, cloud services, and digital infrastructure, they are increasingly vulnerable to risks beyond their direct control. In Black Kite’s 2025 Third-Party Breach Report, we took a closer look into the most significant breaches of 2024 to shed light on the silent breach phenomenon, including why it’s so hard to detect these threats and how you can mitigate them in the year ahead.

The Anatomy of a Silent Breach

Silent breaches are particularly dangerous because they don’t just impact one company — they cascade through entire industries and supply chains, amplifying the damage. Several high-profile incidents from 2024 illustrate just how far-reaching these threats can be:

Blue Yonder ransomware attack:

• Vulnerabilities in Cleo’s Managed File Transfer (MFT) solutions were exploited via the CIOp ransomware group, which targeted companies using unpatched versions of these MFT products. This incident halted production and delayed shipments for hundreds of businesses across multiple industries.

CrowdStrike outage:

• While not a cyberattack or data breach, this service outage exposed the vulnerabilities of interconnected IT systems. Many organizations didn’t realize how reliant they were on CrowdStrike until the damage was done. The blackout affected 8.5 million devices and caused over $5 billion in losses across industries.

These incidents highlight the systemic nature of silent breaches, where vulnerabilities in one organization can quickly lead to widespread disruptions. But what makes these breaches so hard to detect and contain? The answer lies in the complexity of modern supply chains and IT ecosystems.

Why Silent Breaches Are So Hard To Predict and Detect

A perfect storm of fragmented ownership, hidden dependencies, and supply chain blind spots has made silent breaches easy to miss — and even harder to stop. 

Organizations often struggle with governance when it comes to third-party risk, with responsibility often split between security, procurement, and supply chain teams. The lack of clear ownership means risks frequently slip through the cracks, allowing vulnerabilities to remain unchecked.

Many organizations also underestimate the impact of concentration and cascading risk in their third-party ecosystems. Over-reliance on a single vendor creates a single point of failure that can decimate operations if that vendor is compromised. A breach in one organization can also ripple silently through multiple layers of third, fourth, or even fifth parties before anyone realizes the exposure.

Visibility into third-party cyber risk is another major issue. Most organizations have a rough estimate of how many partners they work with, but the actual number is almost always higher. Without complete visibility into how each vendor manages risk, companies are left guessing about their exposure. When a breach occurs, they don’t know who to contact or how to mitigate the damage, leading to significant operational and financial consequences.

The Costs of a Silent Breach

Most organizations aren’t prepared for silent breaches, catching them flat-footed when one occurs. That leads to a range of serious consequences, including:

Operational fallouts:

• A single breach can trigger a chain reaction, causing supply chain delays, service outages, and production stoppages across multiple organizations — and even entire industries.

Financial losses:

• These can include direct costs like ransoms and fines, as well as indirect costs like lost productivity and customer churn. Organizations also need to consider the magnification effect which creates additional delays as each supplier takes time to spin back up. As a result of these delays, organizations may find themselves in breach of their SLAs with customers.

Reputational damage:

• Cyberattacks and breaches can cost you customer trust. Even if a breach originated from one of your vendors, the customer’s focus is on your organization. This can lead to a long-term impact on partnerships, customer loyalty, and brand equity.

Regulations like GDPR, HIPAA, and the Digital Operational Resilience Act (DORA) are attempting to close the gaps that enable silent breaches by enforcing stricter risk management standards. DORA, in particular — which recently came into effect in the EU — explicitly recognizes third-party risk and places increased focus on critical service providers, expanding reporting obligations and resilience testing requirements to these providers.

Proactive Strategies To Stop Silent Breaches

Silent breaches aren’t going away, and compliance alone won’t protect organizations from third-party risks. Organizations must take proactive steps to strengthen resilience across their entire third-party ecosystem. Here’s how cybersecurity leaders can take action in 2025:

1. Establish clear governance
2. Strengthen vendor relationships
3. Adopt continuous monitoring
4. Prioritize prevention
5. Engage in collaborative initiatives

Lets look at each strategy in greater detail.

1 – Establish clear governance

Before organizations can tackle third-party risk, they must first establish a structured governance framework. This framework should identify who assesses vendor risks, how security expectations are enforced, and what escalation procedures exist when risks emerge.

This step also requires bringing all key stakeholders to the table to ensure a shared understanding of third-party dependencies. Security leaders must frame risk in business terms, making it clear how a vendor’s cybersecurity weaknesses could disrupt operations. Black Kite’s FocusTags™ and Cyber Risk Quantification provide CISOs with the data they need to drive these conversations, helping quantify vendor risk and prioritize mitigation efforts based on real business impact.

2 – Strengthen vendor relationships

Rather than seeing vendors as adversaries, organizations need to focus on creating strong, collaborative relationships. Organizations must move beyond static security questionnaires and engage in ongoing conversations about risk.

Cybersecurity expectations should be explicitly written into vendor contracts. Instead of generic security demands, organizations should provide vendors with precise data on vulnerabilities and step-by-step remediation guidance. Tools like Black Kite Bridge™ help streamline this process by eliminating communication gaps and enabling organizations to easily share actionable intelligence with vendors.

3 – Adopt continuous monitoring

Continuous monitoring provides the real-time intelligence needed to track vendor security posture and respond before threats escalate. Instead of starting from scratch when a new zero-day vulnerability is announced, you can instantly pinpoint which third parties are exposed and act accordingly.

Black Kite’s FocusTags™ help organizations continuously assess risks, while the Supply Chain Module maps dependencies and monitors vendor ecosystems for potential disruptions and single points of failure.

4 – Prioritize prevention

Stopping silent breaches requires a shift from reactive responses to proactive vulnerability management. Black Kite’s Ransomware Susceptibility Index® (RSI™) is a powerful tool to uncover the likelihood of an attack across third-party vendors, helping develop effective remediation steps ahead of time.

Updating your approach to compliance gap analysis can also reduce the administrative load on both sides. Traditional security assessments overwhelm vendors with long, generic questionnaires that often fail to capture real risks. Black Kite’s AI-powered compliance gap analysis replaces these questionnaires, analyzing vendor security frameworks to pinpoint compliance gaps. Instead of answering hundreds of irrelevant questions, vendors receive a tailored set of questions, ensuring they focus on the most pressing security improvements.

5 – Engage in collaborative initiatives

Real resilience comes from collaboration — both internal and external. Compliance mandates like DORA and the NIST Cybersecurity Framework provide a solid starting point, but security leaders must go beyond regulatory checkboxes. 

Strengthening internal alignment is the first step, ensuring security, risk, and procurement teams work together. From there, expanding collaboration externally is critical to staying ahead of evolving threats. Industry-specific groups like ISACs (Information Sharing and Analysis Centers) foster intelligence-sharing and collective defense, while cross-industry collaboration initiatives like ISSA and CISOs Connect™ help security leaders anticipate emerging risks.

Vendors must also be part of this equation. Encouraging them to participate in collaborative initiatives and using tools like Black Kite Bridge™ can help engage vendors in the threat intelligence process, strengthening security partnerships.

Creating a Roadmap To Beat Silent Breaches

Silent breaches might have dominated 2024’s cyber threat landscape, but they don’t have to define the future. The hard lessons from these attacks offer a blueprint for resilience. By taking a proactive approach — strengthening governance, improving vendor collaboration, and continuously monitoring for hidden risks — organizations can turn the tide against silent breaches in 2025.

Read the 2025 Third-Party Breach Report for more insights to avoid the next silent breach.