Log4j “Log4Shell” RCE explained (CVE-2021-44228). Hello everyone! I decided to make a separate episode about Log4Shell. Of course, there have already been many reviews of this vulnerability. But I do it primarily for myself. It seems to me that serious problems with Log4j and similar libraries will be with us for a long time. Therefore, it would be interesting to document how it all began. So what is the root cause of Log4Shell?
Logs
Generally speaking, the IT infrastructure of any company deals with streams of input data. From user requests to a corporate website to integration with banking APIs and cloud services. A lot of data gets into the infrastructure of the company, is transferred from system to system, periodically getting into the logs. These logs are required to verify that the systems are functioning correctly.