The number of data breaches has risen in recent years. Some of the most high profile cases in recent times include the Marks & Spencer 2025 breach that saw hackers access a large amount of customer data and cause the business to halt its online retail options for over a month. The Legal Aid Agency also suffered a data breach in April 2025, which is comprised of personal, financial, and legal data from 2010 onwards.
Data breaches are becoming so common that tools are being built for individuals to check if their information has been compromised. But what exactly is a data breach, how do they occur, and why are they becoming more frequent?
What Is a Data Breach?
A data breach occurs when an unauthorised party manages to access an organisation’s protected, sensitive or confidential data. This might not always involve stealing the data; in some cases, it can be simply copied or viewed. A breach typically involves three stages:
- Probing: The unauthorised party identifies vulnerabilities in an organisation’s security system. Weak passwords and password sharing are common forms of human error that can lead to breaches.
- Penetration: Next, the unauthorised party enters the organisation’s network using one of the vulnerabilities they have discovered. Often, this occurs due to inadequate security measures on routers and other connection devices. Staff could also be exploited or manipulated into providing access using a number of tactics, including extortion.
- Extraction: The final stage is for the criminals to extract the organisation’s data, either digitally or by manually copying it.
What Constitutes a Data Breach Under UK GDPR?
A breach is any incident impacting the confidentiality, integrity, or availability of personal data. Under UK GDPR, all businesses are required to implement appropriate technical and organisational measures to protect personal data. Breaches can be catastrophic for businesses. The theft of company data can lead to crimes such as identity theft, particularly when customer data – including credit card numbers – is the subject of the breach. Or corporate espionage, where valuable plans, designs, or types of other intellectual property are accessed.
Types of Data Breaches
Data breaches can originate from many sources:
External breaches
These are often associated with cyber attacks such as phishing and ransomware, which are among the most common methods used to gain unauthorised access to data from outside an organisation Attackers can exploit third-party services, suppliers, or platforms used by an organisation or its employees. In 2024, a study found that nearly 450 Members of Parliament had had their personal information exposed on the dark web after being exposed through hacks, breaches of third-party services, or other compromise methods, rather than direct attacks on Parliament’s own IT systems.
Internal breaches
Internal breaches occur as a result of staff errors or unauthorised internal access. Employees may unknowingly or deliberately access data they are not permitted to see or alter. In some cases, authorised individuals misuse their power to access data and share it with criminals.
Negligence or theft
Breaches can occur if a device is left unattended, stolen, or if confidential documents are not secured. If unauthorised individuals access these items, company data can be exposed.
System failures
System failures can also result in data breaches. Glitches or failures within systems can unintentionally allow unauthorised access, compromising the security of sensitive information.
How Do Data Breaches Occur?
According to the UK Government’s Cyber Security Breaches Survey 2025 and the Information Commissioner’s Office (ICO), the most common ways breaches occur are:
Physical actions
Loss or theft of laptops, USB drives, or paperwork containing sensitive data. This can occur if individuals are careless with company data, or after the theft of paperwork or an employee’s laptop.
Privilege problems
Incidents where staff access or share data without proper authorisation. These breaches can happen either accidentally or deliberately. It can also occur when authorised individuals abuse their power to access data and pass it on to criminals.
Social engineering
Increasingly, attacks are coming from criminals pretending to be banks, clients, auditing agencies, or even the police. This kind of trick uses the trust of workers to gain entry to networks. It also concerns email and other electronic communications scams such as phishing, where people pretend to be a provider that the organisation already uses.
Human error
Mistakes such as sending data to the wrong recipient, misconfiguring systems, or using weak passwords can all be down to human error. No matter how many preventative measures are put in place, businesses still suffer from people making mistakes, often unwittingly.
Malware and ransomware
Malware attacks use malicious software to steal or lock data, and the internet is full of bots and spyware that can access networks with little-to-no human help. Ransomware has become a popular type of malware, blocking access to data or systems and demanding payment to restore it. Most of these breaches are carried out by hackers or organised cyber criminal groups. They use a mix of technical exploits, malware, and social engineering to gain unauthorised access to sensitive information. Once inside, they can cause serious disruption and damage. The causes of data breaches can be grouped into the three main categories:
| Category | Specific Causes | Examples |
| Malicious, Intentional, or Criminal |
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| System Glitches |
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| Human Error |
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Trends and Statistics
As technology has advanced and become more crucial to daily operations, the number of data breaches is significant. In 2024, 43% of all UK businesses and 30% of charities reported having experienced any kind of cyber security breach or attack in the last 12 months. While this is a slight drop from the previous year, the prevalence of cyber breaches and attacks in medium and large businesses remains high.
Why Are Data Breaches So Common?
The frequency of data breaches could be driven by several factors. The increasing sophistication of cyber criminals plays a significant role, as they continually develop new methods to exploit vulnerabilities. The growing reliance on digital data storage further exacerbates this issue, providing more targets for potential attacks. Human error also remains a persistent factor, with mistakes such as weak passwords and improper data handling creating opportunities for breaches. The expansion of internet-connected devices and remote working has broadened the attack surface over recent years, making it easier for unauthorised parties to gain access to sensitive information. AI is also enhancing criminal activities – read about the latest cyber security trends.
What Are the Consequences of a Data Breach for UK Businesses?
The effects of a data breach are typically damaging for the organisation concerned. Firstly, under the Data Protection Act 2018 and UK GDPR, the ICO can fine you – the maximum penalty is £17.5 million or 4% of annual global turnover, whichever is higher. When the dust has settled on the fine, the next problem is the reputational damage caused by the breach. Even if the breach is incredibly complex, the perception amongst the public could be that the breached organisation has weak security and inadequate countermeasures. Customers may move away from a business that cannot keep their data safe to avoid the risk of confidential information like addresses and health records being made public. If the bank records and credit card numbers of customers are stolen, then these individuals will have to take rapid action to avoid identity theft, which could destroy any relationship with the organisation.
What do I do if there is a breach?
If your organisation has suffered a data breach, there are steps you urgently need to take to protect your customers and your business. Under the UK GDPR and Data Protection Act 2018, organisations must report personal data breaches that pose a risk to individuals to the ICO, typically within 72 hours. ISO 27001 certification provides a set of requirements for businesses to meet to help manage data breaches efficiently, particularly in complying with UK GDPR. Read about when to report a breach to the ICO
How Can ISO Certification Help With Data Breaches?
For organisations looking to enhance their data security, a variety of certifications could help. Cyber Essentials helps businesses protect themselves against common cyber threats, while Cyber Essentials Plus offers hands-on technical verification. Both are backed by the UK Government. ISO 27001 helps businesses to establish a comprehensive Information Security Management System (ISMS) to manage information security risks and structured responses. Adopting these certifications and their requirements can significantly enhance an organisation’s ability to handle data securely and mitigate the risk of breaches. Get a quote for your business or contact our expert team for more information about how certification can support your organisation.
