In the last few years, there has been a sharp rise in software supply chain attacks, where malicious actors target software build and deployment environments to infiltrate production systems. There are three reasons that have contributed to this increase:  

Improved security for production systems has forced attackers to look for other avenues. The improvements may be due to the increase in cloud and managed services and general security awareness and availability of tools.  
With the adoption of programmable infrastructure and Infrastructure-as-Code (IaC), build, and delivery systems now have access to production systems. This means a compromise in the build system can be used to access production systems and, in the case of a software vendor, access to customer environments.
Applications are increasingly composed of hundreds of OSS and commercial components. This increases the application exposure and presents several ways to add malicious code to an application.

All of these factors contributed to attackers shifting focus to Continuous Integration and Continuous Delivery (CI/CD) systems as an easier target to infiltrate multiple production systems. Therefore, it is essential that organizations give equal consideration to securing our CI/CD pipelines, just as they do their production workloads.