CI/CD Pipeline Under Siege: Attackers Weaponize Trusted Build Infrastructure

Breaking News — The software supply chain is under a new and insidious threat: attackers are no longer just poisoning dependencies or hijacking packages. In 2025, the focus has shifted to the very infrastructure that powers the software delivery lifecycle — build servers, CI/CD runners, package managers, and developer workstations — all of which sit inside an organization's trusted delivery path.

According to a leading cybersecurity firm's annual threat report, these systems are designed to execute code automatically with elevated privileges, making them ideal attack surfaces. Once compromised, malicious activity blends seamlessly into legitimate build and release workflows, often going undetected for months.

“Adversaries are adopting ‘shift-left’ tactics to subvert build runners and poison development dependencies before code ever reaches a production server,” said Dr. Elena Marchetti, a senior threat researcher at the security firm. “Instead of breaching the perimeter, they are compromising the systems that organizations inherently trust to deliver software.”

Background: The Subversion of Trusted Infrastructure

Build servers and runners are high-value targets because they routinely execute privileged actions — compiling code, pulling dependencies, moving artifacts, and deploying software. These activities mirror the behavior of an attacker attempting to establish persistence or distribute malware.

In one documented case, attackers exploited a vulnerable self-hosted TeamCity server and remained undetected for over a year. After gaining access, they created a benign-looking build configuration executed by a trusted build agent with SYSTEM privileges. That build job then deployed a backdoor into internal environments.

“Since the malicious code was delivered through a legitimate CI/CD task, it appeared indistinguishable from normal operational activity,” Marchetti explained. “No suspicious external binary was introduced, and the deployment path blended into routine release workflows.” This highlights the core challenge: in CI/CD environments, malicious behavior often looks exactly like expected behavior.

What This Means: Turning Automation Against the Organization

Pipeline compromise does not always require direct malware execution on the build server. In many cases, attackers manipulate automation workflows to make the organization's own tools carry out the intrusion.

One observed intrusion involved the compromise of a GitLab service account token. The attacker used that token to create projects containing malicious code, which were then built and released automatically by the trusted pipeline. This allowed the attacker to bypass traditional security controls by abusing automation itself.

The implications are profound. Traditional security tools that scan for malware at the perimeter are ineffective when the attack originates from within the trusted delivery path. Security teams must now monitor for anomalous behavior inside CI/CD pipelines, treat build systems as critical assets, and implement strict access controls and audit logging.

“This is a fundamental shift in threat landscape,” said James Cartwright, a former CISO and now independent consultant. “We can no longer assume that code coming from our own build servers is safe. We need to verify the pipeline itself.”

Key Takeaways

• Attackers are targeting CI/CD infrastructure directly, not just software dependencies.
• Compromised build servers can deploy backdoors that look like legitimate releases.
• Stolen service account tokens enable weaponizing automation pipelines.
• Traditional perimeter defenses fail because malicious activity mimics expected actions.
• Organizations must adopt “zero trust” for their software delivery infrastructure.

As attacks grow more sophisticated, the industry is urged to revisit how trust is established in the software supply chain. “The days of trusting the pipeline by default are over,” Marchetti concluded. “Every build, every deployment must be scrutinized.”