You’ve heard of tech debt, those shortcuts in development that come back to bite you later. Well, meet its close cousin: security debt. And if the recent attacks on M&S, Co-op, and Harrods tell us anything, it’s that this kind of debt doesn’t stay hidden for long.

Security is easy to deprioritise when everything’s working fine. Until suddenly, it’s not. These weren’t just headline-grabbing data breaches. They brought operations to a standstill; online stores offline, supply chains frozen, and transactions halted.

What Actually Happened?

• M&S: Ransomware took down their online store, disrupting orders and shaking customer trust.
• Co-op: A supply chain attack impacted order fulfilment, grinding operations to a halt.
• Harrods: Though they were hit too, their fast recovery showed the difference a solid response plan makes.

These incidents didn’t come out of nowhere. They were the result of accumulated decisions: skipped updates, unpatched systems, and no clear plan. That’s what we call security debt and it builds up until the day it gets “collected.”

What Is Security Debt?

It’s the cost of postponing security, the slow pile-up of risk from:

• Outdated software
• Weak password policies
• Lack of employee training
• No incident response plan

Alone, these seem manageable. Together? They create a fragile foundation that can’t hold when an attack hits.

It’s Bigger Than Data Loss

In 2025, the average cost of a retail breach hit $3.3 million (IBM). That’s just the tip of the iceberg. Reputational damage, operational downtime, and lost customer trust? Those are harder to measure and harder to recover from.

A recent study found 61% of retailers faced a cyberattack last year, with ransomware up 33% year-over-year. These aren’t isolated incidents. They’re part of a pattern.

What Sets Survivors Apart?

Preparation.

Harrods bounced back because they had a tested incident response plan. They knew who to call, what steps to take, and how to communicate clearly.

M&S and Co-op, on the other hand, were caught off guard. Their recovery took longer, not because the attacks were worse, but because the response wasn’t ready.

What Can We Learn?

Cybersecurity isn’t just an IT issue, it’s a business continuity issue. Here’s how to tackle your security debt before it catches up with you:

• Run regular vulnerability assessments
• Train employees to spot phishing and social engineering
• Keep software and systems updated (yes, even the legacy ones)
• Build and test an incident response plan

The Bottom Line

The attacks on M&S, Co-op, and Harrods aren’t just cautionary tales. They’re reminders that security debt is real... and expensive.

The good news? You can start paying it down today.

So ask yourself: If an attack hit tomorrow, how fast could you bounce back?