Critical Java Log4j Vulnerability

Critical Java vulnerability log4j, CVE-2021-44228

What can go wrong with a tool that just logs messages to a text-based file? Nothing right? That is what virtually every organization on the planet must have been thinking because they all use log4j. Of course, the reality is proving us all wrong. Suddenly on December 11, 2021, we were all exposed to the Log4J vulnerability and our organization could have been (might have been?) breached!

Log4j Vulnerability Explained

Log4j is an extremely popular and heavily used open-source Java library that can be used for unauthenticated remote-code execution, making CVE-2021-44228 and CVE-2021-45046 critical vulnerabilities that you must pay attention to.

In other words: if your software uses this library, then there is a good chance that anyone can gain full remote control of your servers and data.

The log4j vulnerability is among the worst we’ve seen in the last 5 years, in part because the vulnerability itself is so severe and so easy to trigger. Adding to the severity, this vulnerable library is among the most popular and widely deployed open-source Java libraries on the planet.

Differences between log4j vulnerability versions?

The Apache Struts disaster from 2017 (CVE-2017-5638) was a large part of why we launched our startup (mergebase.com): to help companies protect themselves from known-vulnerabilities in open source libraries exactly like these.

This time it’s even worse. Globally, everyone must now urgently scramble to upgrade all applicable software to use Java library log4j version at least 2.15.0 (which was published today). Companies that for whatever reason fail to execute on this upgrade will likely be attacked and exploited within the next few days – assuming they are not already under attack.

We cannot stress how urgent it is for administrators of Java systems to succeed in rolling out this upgrade. Patch this Critical log4j vulnerability in Java CVE-2021-44228 immediately.

How can you check for vulnerabilities?

There is an easy way to check any server for the log4j vulnerability. At the root of your file system, using an administrator account, download and run our free Log4J-Detector tool: https://github.com/mergebase/log4j-detector

This command can take several hours to complete. Any occurrence of “_VULNERABLE_” in this command’s output indicates with high probability that you are vulnerable to this severe software exploit.

monitoring - Log4j vulnerability

Further reading: https://www.lunasec.io/docs/blog/log4j-zero-day/

Still interested in learning more about it? Check the video on securing log4j instantly with run-time protection.

MergeBase can help you patch your vulnerable systems to eliminate this bug and help you in situations where patching is not possible. We have a patented cyber-security technique for exactly this situation.

You can try MergeBase to see if you are vulnerable, or download our free tool to detect vulnerable log4j versions on any of your machines and in any application.

Julius Musseau

About the Author

Julius Musseau

Julius Musseau, co-founder & CTO. Senior architect and developer with strong academic background and roots in the open source community. Contributor to a number of important open source projects.