Currently there are so many suggested steps that have been posted for excluding log4j-core library from dependency or upgrading to the latest (above version 2.15) version according to Spring Blog . Are there any recommended tools that can be used for protecting spring application deployed in Google App Engine or Pivotal Cloud Foundry(PCF) for protecting instead of patching them for redeployment?
Another necessary question is, does it make my application(microservice spring application) to be vulnerable if it uses another microservice for some of its service if it depends on another microservice and if that microservice already uses vulnerable version of log4j-core?
In regard to your first question, you can set an environment variable in order to disable the replacement lookups in log4j:
LOG4J_FORMAT_MSG_NO_LOOKUPS=true
Please note that this only works for log4j >= 2.10.
I believe you can set environment variables in PCF without having to redeploy the service (of course, a restart would be needed), so no new release would be needed. See: https://docs.pivotal.io/pivotalcf/2-3/devguide/deploy-apps/environment-variable.html and https://cli.cloudfoundry.org/en-US/v6/set-env.html
In order to see whether your spring-boot application is vulnerable to the exploit, you could use a spring-boot test I created for that purpose: https://github.com/chilit-nl/log4shell-example - You could test your application with and without the environment variable, to see if it has any effect (assuming that your application currently is vulnerable).