I'm looking for ways to further protect my web app against supply chain attacks.
Attacks focusing on supply chain have been increased a lot recently. NIST is working on a recommendation, following the May 2021 Executive Order, and questions about this have already been asked here (How does one defend against software supply chain attacks?, ...).
The short answer is usually that it's not possible to protect yourself against supply chain attacks. I am however looking at ways to increase the security of my web application, which heavily uses open source dependencies, such as java (maven) and javascript (npm). My code ("jars", ...) is not distributed but rather deployed as a service on a privately owned server.
Apart from replies or link to recommendations about this broad topic, I'm also more specifically interested in ways to protect my build process (CI/CD pipeline, using jenkins), and integrity checking (it seems that jar signing for instance is not really recommended, but maybe this recommendation has evolved due to the increasing popularity of this subject).
EDIT: In other words, what are the various ways (type of attacks, not attacks themselves) that rely on software supply chain attacks (i.e. targetting dependencies, and the build process), and how to protect against them ? I know that one of them is the "dependency confusion", where a threat actor adds to a public repo the name of a private dependency I use, in hopes I'll use theirs instead. Are there others ?