The build process is the stage where source code is transformed into a runnable program or package. In many language ecosystems, it does more than compile code: it may run build scripts, fetch dependencies, generate files, and read local environment data. That means a build is not just a technical step, but an execution environment with access to source trees, configuration files, and sometimes secrets on a developer or CI machine.
This matters in cyber security because attackers can abuse trusted build steps to steal code, tokens, or other sensitive data. A malicious dependency or build script may run automatically during compilation and quietly collect files or environment variables. Defenses include isolating builds, limiting filesystem and network access, pinning dependency versions, reviewing changes to build scripts, and keeping secrets out of environments that compile untrusted code.