Threat actors can use the Log4j exploit to take control of hacked web-facing servers by feeding them a malicious text string. It's part of Log4j, an open-source Apache module for logging Java-based applications' faults and events.
Developers use Log4j to track what happens in their software applications or internet services. It's essentially a massive log of a system's or application's activities. This practise is known as logging, and it is utilised by developers to keep track of user issues.
According to Sonatype, which controls the Maven Central repository, which is regarded the most major repository of Java packages, more than 40% of users continue to download insecure versions of Apache Log4j despite urgent efforts to upgrade the software.