I've heard that it's crucial to run Docker builds in a CI/CD pipeline with minimal privileges. However, after struggling with tools like Kaniko and BuildKit, I'm trying to understand why that is. I get that using elevated privileges increases potential attack vectors, but what are the actual risks involved? My CI/CD setup is on EC2 instances within an Auto Scaling Group, so a privilege escalation on those hosts wouldn't give an attacker access to anything valuable. Can someone explain whether I should keep trying to avoid elevated privileges, or if I'm just overthinking this?
5 Answers
You definitely want to avoid running builds as root. It’s similar to why you don’t want to run web servers as root; if compromised, it limits the damage that could occur. Using a regular user for builds helps contain any potential fallout. If your build gets taken over, the damage can be limited because the attacker can’t gain control of every process running on the server.
Elevated privileges expand your attack surface. If something malicious makes it into your build environment, it could potentially breakout from the container and affect the host, even on EC2s. Leaked credentials or unintended lateral movements could compromise your entire setup—even if it’s just dedicated CI nodes. Stick to rootless builds and user namespaces if you can!
The main problem with using elevated privileges is that it can lead to security breaches. If a component in your build process is compromised, like a bad Dockerfile or a vulnerable package, the attacker could gain root access to your host. This breaks the isolation that containers offer. Sticking to a ‘least privilege’ model is super important; it minimizes the risk of a compromised build impacting your entire infrastructure.
Even if your build environment seems low-risk, it’s still a key target. That’s where all your code lives, and if an attacker can alter something in your builds, they could easily backdoor your releases. Just because your repos are private doesn’t mean they lack value. You want to keep your builds secure to prevent any malicious alterations that could have a long-term impact on your projects.
Totally agree! A lot of people underestimate the importance of securing their CI/CD pipeline. If a malicious package slips through, it can cause major issues.
Just to clarify, if an EC2's main job is running containers, is there still a risk? Can you give me an example of how this might go sideways?
Absolutely, even if the EC2s seem isolated, a compromised container can still pose a threat. If an attacker gains access, they could potentially escalate their privileges and pivot further into your infrastructure. It’s always wiser to follow best practices and run builds with the least privilege necessary.
That’s a solid point. Any vulnerabilities in your build chain can become a major security risk if not handled properly.