[SECURITY] Apache Solr affected by Apache Log4J CVE-2021-44228

Due to the discovery of the CVE-2021-44228 vulnerability in Apache Log4j2 which is used in Apache Solr, it is necessary to take countermeasures that will eliminate any potential risk.

As described here: https://solr.apache.org/security.html#apache-solr-affected-by-apache-log4j-cve-2021-44228, the vulnerability applies to all versions of Apache Solr using the Log4j2 library. The page lists a number of solutions that will eliminate the problem.

One of these solutions involves manually updating the log4j2 component to version 2.16.0 (or higher). Download Apache Log4j 2 binary (zip) from here: https://logging.apache.org/log4j/2.x/download.html

At the time of creating this article, the latest version is 2.16.0 (and this version will be used in the manual). 

How to manually replace log4j2 files

In this example, the search component is installed on disk D: in the default folder, on a machine available under DNS name solserver.

1. Download Apache Log4j 2 binary (zip) from https://logging.apache.org/log4j/2.x/download.html
2. Stop Webcon BPS Search Service

3. Delete the following files from folder D:\Program Files\WEBCON\WEBCON BPS Search Server\Search Cluster\Solr\contrib\prometheus-exporter\lib\
   - log4j-api-2.13.2.jar
   - log4j-core-2.13.2.jar
   - log4j-slf4j-impl-2.13.2.jar

4. Delete the following files from folder D:\Program Files\WEBCON\WEBCON BPS Search Server\Search Cluster\Solr\server\lib\ext\
   - log4j-1.2-api-2.13.2.jar
   - log4j-api-2.13.2.jar
   - log4j-core-2.13.2.jar
   - log4j-slf4j-impl-2.13.2.jar
   - log4j-web-2.13.2.jar
5. Copy the following files from the downloaded archive:
   - log4j-api-2.16.0.jar
   - log4j-core-2.16.0.jar
   - log4j-slf4j-impl-2.16.0.jar
6. Paste the copied files in folder D:\Program Files\WEBCON\WEBCON BPS Search Server\Search Cluster\Solr\contrib\prometheus-exporter\lib\
7. Copy the following files from the downloaded archive
   - log4j-1.2-api-2.16.0.jar
   - log4j-api-2.16.0.jar
   - log4j-core-2.16.0.jar
   - log4j-slf4j-impl-2.16.0.jar
   - log4j-web-2.16.0.jar
8. Paste the copied files in folder D:\Program Files\WEBCON\WEBCON BPS Search Server\Search Cluster\Solr\server\lib\ext\
9. Start Webcon BPS Search Service
10. Verify whether the search server functions correctly by e.g. opening the following in a browser:
    - http://solrserver:8983
    - http://solrserver:8983/solr/BPS_Activities/query?q=*&rows=1
    - http://solrserver:8983/solr/BPS_Elements/query?q=*&rows=1