Following the discovery of Log4Shell, a vulnerability in Log4J2, Elastic released a blog post describing how users of our platform can leverage Elastic Security to help defend their networks. We also released an advisory detailing how Elastic products and users are impacted.

Very recently, the JFrog security research team has disclosed an issue in the H2 database console which was issued a critical CVE – CVE-2021-42392. This issue has the same root cause as the infamous Log4Shell vulnerability in Apache Log4j (JNDI remote class loading). H2 is a very popular open-source Java SQL database offering a lightweight in-memory solution that doesn’t require data to be stored on disk.

If you find yourself baffled by the influx of events and newly discovered vulnerabilities affecting the popular Apache Log4j Java logging library, this post is for you. This post aims to survey the entire flow of events since the first discovery of CVE-2021-44228, AKA Log4Shell, to the present date, explain the important aspects of each related vulnerability, as well as provide practical remediation and mitigation advice.

No matter your role in tech, you’ve probably already heard about, or dealt with, the ubiquitous Log4Shell vulnerability impacting a large number of Java applications. To help spread the latest info on this critical, zero-day vulnerability, we recently hosted a webinar to get everyone up to speed.

​​Since December 10, in a span of just 20 days, there have been four different vulnerabilities published against Log4j. Engineers who worked long hours to update their Log4j versions to 2.15.0 on December 11th, were told three days later that they needed to do it all over again and upgrade to version 2.16.0. This is not sustainable. And yet the risks are high. Looking backward, we see that Log4j has been vulnerable since 2013 to the kinds of attacks described in CVE-2021-44228.

The high risk associated with newly discovered vulnerabilities in the highly popular Apache Log4j library – CVE-2021-44228 (also known as Log4Shell) and CVE-2021-45046 – has led to a security frenzy of unusual scale and urgency. Developers and security teams are pressed to investigate the impact of Log4j vulnerabilities on their software, revealing multiple technical challenges in the process.

Following the Dec. 9, 2021, announcement of the Log4j vulnerability, CVE 2021-44228, CrowdStrike Falcon OverWatch™ has provided customers with unrivaled protection and 24/7/365 vigilance in the face of heightened uncertainty. To OverWatch, Log4Shell is simply the latest vulnerability to exploit — a new access vector among a sea of many others.

Another — though unlikely — vulnerability was discovered in Log4j’s latest versions: CVE-2021-44832. This is an Arbitrary Code Execution exploit using, yet again, the now infamous JNDI functionality. The vulnerability lets an attacker with control over the Log4j configuration set a malicious datasource for the JDBC (Java DataBase Connectivity API) appender. The datasource refers to an attacker-controlled JNDI URI that will execute arbitrary code on the application using Log4j.