Legacy system

A legacy system is any software, hardware, or technology that is outdated but still in use. These systems were often cutting-edge when they were implemented.

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A legacy system, in the context of computing, refers to an old method, technology, computer system, or application program that continues to be used, typically because the user (typically a business or organization) does not want to replace or redesign it. Legacy systems can have a significant impact on cybersecurity, as they often contain vulnerabilities that can be exploited by malicious actors. This article will delve into the complexities of legacy systems, their implications for cybersecurity, and strategies for managing and mitigating the risks associated with them.

Understanding legacy systems and their role in cybersecurity is crucial for any organization that relies on technology for its operations. As technology continues to advance at a rapid pace, the challenge of maintaining and securing legacy systems becomes increasingly complex. This article will provide a comprehensive overview of legacy systems, exploring their origins, their common characteristics, the challenges they pose, and the strategies that can be employed to manage these challenges.

What is a legacy system?

A legacy system is any software, hardware, or technology that is outdated but still in use. These systems were often cutting-edge when they were implemented, but over time, they have been surpassed by more advanced technologies. However, for various reasons, organizations continue to use these systems. These reasons can include the high cost of upgrading or replacing the system, the system's integration with other critical systems, or the lack of available alternatives that meet the organization's specific needs.

Legacy systems can include everything from outdated operating systems and software applications to old hardware devices and network infrastructure. They are typically characterized by their lack of support from vendors, their incompatibility with newer technologies, and their increased vulnerability to security threats. Despite these challenges, legacy systems often play a critical role in an organization's operations, making their management a crucial aspect of an organization's cybersecurity strategy.

Characteristics of legacy systems

Legacy systems are typically characterized by a number of common traits. These include outdated technology, lack of vendor support, and incompatibility with newer systems and technologies. Because of these characteristics, legacy systems often require specialized knowledge and skills to maintain and operate. This can make them costly to maintain, as the pool of individuals with the necessary skills and knowledge is often limited.

Another common characteristic of legacy systems is their deep integration with an organization's operations. These systems often support critical business processes, and their failure could have significant impacts on the organization's ability to operate. This deep integration can make replacing or upgrading these systems a complex and risky process, as any changes could potentially disrupt the organization's operations.

Examples of legacy systems

Examples of legacy systems can be found in many different industries and sectors. In the banking industry, for example, many financial institutions still rely on mainframe computers and COBOL programming language, both of which are decades old. These systems are often used to process transactions and manage customer accounts, making them critical to the bank's operations.

In the healthcare sector, many hospitals and healthcare providers still use outdated software applications to manage patient records and billing. These systems are often incompatible with newer technologies, making it difficult to integrate them with other systems or to implement new features or functionalities. Despite these challenges, these systems are often deeply ingrained in the organization's operations, making their replacement a complex and potentially risky process.

Implications for cybersecurity

Legacy systems pose significant cybersecurity risks. Because these systems are outdated, they often contain vulnerabilities that can be exploited by malicious actors. Additionally, because these systems are no longer supported by their vendors, these vulnerabilities are often left unpatched, making them an attractive target for cybercriminals.

Furthermore, the specialized knowledge and skills required to maintain and operate legacy systems can make it difficult for organizations to ensure that these systems are properly secured. This lack of expertise can lead to gaps in an organization's cybersecurity defenses, further increasing the risk of a cyber attack.

Common security risks

Legacy systems are often riddled with security vulnerabilities. These can include everything from outdated encryption algorithms to unpatched software vulnerabilities. These vulnerabilities can be exploited by cybercriminals to gain unauthorized access to the system, steal sensitive data, or disrupt the organization's operations.

Another common security risk associated with legacy systems is their lack of compatibility with modern security tools and technologies. Many legacy systems cannot support the latest encryption standards or security protocols, making it difficult to secure them against modern threats. Additionally, many legacy systems do not support the use of security tools such as intrusion detection systems or firewalls, further increasing their vulnerability to cyber attacks.

Case Studies of legacy system breaches

There have been numerous instances where legacy systems have been the target of cyber attacks. One notable example is the 2017 WannaCry ransomware attack, which targeted vulnerabilities in Microsoft's Windows XP operating system. Despite the fact that Microsoft had ended support for Windows XP three years prior to the attack, many organizations were still using the outdated operating system, leaving them vulnerable to the attack.

Another example is the 2014 breach of the U.S. Office of Personnel Management (OPM). The breach, which resulted in the theft of personal information of millions of federal employees and contractors, was attributed in part to the OPM's use of outdated and insecure legacy systems. The breach highlighted the significant security risks associated with the use of legacy systems, and led to calls for the U.S. government to invest in upgrading its IT infrastructure.

Managing legacy systems

Given the significant security risks associated with legacy systems, it is crucial for organizations to have strategies in place to manage these systems. These strategies can include everything from regular system audits and vulnerability assessments to the development of contingency plans in case of system failure.

One of the most effective ways to manage the security risks associated with legacy systems is to upgrade or replace these systems with newer, more secure technologies. However, this is often easier said than done. The cost of upgrading or replacing a legacy system can be prohibitive, and the process can be complex and risky. Furthermore, in many cases, the legacy system is so deeply integrated with the organization's operations that replacing it is simply not feasible.

Strategies for securing legacy systems

There are several strategies that organizations can employ to secure their legacy systems. One of these is to implement a layered security approach. This involves using multiple security measures to protect the system, with each layer providing a backup in case the previous layer fails. This can include everything from firewalls and intrusion detection systems to regular system audits and employee training programs.

Another strategy is to isolate the legacy system from the rest of the organization's network. This can be achieved through the use of network segmentation, which involves dividing the network into separate segments, each with its own security controls. By isolating the legacy system, organizations can limit the potential damage that can be caused if the system is compromised.

Upgrading and replacing legacy systems

Upgrading or replacing a legacy system is often the most effective way to mitigate the security risks associated with these systems. However, this process can be complex and costly. It requires careful planning and execution to ensure that the new system meets the organization's needs and that the transition does not disrupt the organization's operations.

When upgrading or replacing a legacy system, it is important to conduct a thorough assessment of the system's functionality and the organization's needs. This can help to identify any potential issues or challenges that may arise during the transition. Additionally, it is important to ensure that the new system is compatible with the organization's existing systems and technologies, and that it can be integrated smoothly into the organization's operations.


Legacy systems pose significant challenges for organizations, particularly in terms of cybersecurity. Despite their outdated technology and increased vulnerability to cyber attacks, these systems often play a critical role in an organization's operations, making their management a crucial aspect of an organization's cybersecurity strategy.

By understanding the risks associated with legacy systems and implementing effective strategies to manage these risks, organizations can ensure that their legacy systems continue to support their operations while minimizing their vulnerability to cyber threats. Whether through upgrading or replacing these systems, implementing layered security measures, or isolating these systems from the rest of the network, there are numerous strategies that organizations can employ to secure their legacy systems and protect their operations.

Author Sofie Meyer

About the author

Sofie Meyer is a copywriter and phishing aficionado here at Moxso. She has a master´s degree in Danish and a great interest in cybercrime, which resulted in a master thesis project on phishing.

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