Welcome to Elastic’s Log4j2 vulnerability information hub. Here we will explain what the specific Log4j2 vulnerability is, why it matters, and what tools and resources Elastic is providing to help negate the opportunity for malware exploits, cyberattacks, and other cybersecurity risks stemming from Log4j2.
A third Log4j2 vulnerability was disclosed the night between Dec 17 and 18 by the Apache security team, and was given the ID of CVE-2021-45105. According to the security advisory, 2.16.0, which fixed the two previous vulnerabilities, is susceptible to a DoS attack caused by a Stack-Overflow in Context Lookups in the configuration file’s layout patterns. What is this CVE about? What can you do to fix it? How does it differ from the previous CVEs?
Log4j, Log4j, Log4j. Let’s see you say that 10 times fast. If you can’t, then you may need to learn because Log4j is on the tips of everyone’s tongues right now. In fact, people are calling Log4j the biggest security breach since Tutar, Borat’s movie daughter, sneaked into The White House and had a lively face-to-face conversation with President Trump.
Log4j, Log4j, Log4j. Let’s see you say that 10 times fast. If you can’t, then you may need to learn because Log4j is on the tips of everyone’s tongues right now. In fact, people are calling Log4j the biggest security breach since Tutar, Borat’s movie daughter, sneaked into The White House and had a lively face-to-face conversation with President Trump.
Last week, a researcher from the Alibaba Cloud Security Team dropped a zero-day remote code execution exploit on Twitter, targeting the extremely popular log4j logging framework for Java (specifically, the 2.x branch called Log4j2). The vulnerability was originally discovered and reported to Apache by the Alibaba cloud security team on November 24th. MITRE assigned CVE-2021-44228 to this vulnerability, which has since been dubbed Log4Shell by security researchers.
Overnight, it was disclosed by Apache that Log4j version 2.16 is also vulnerable by way of a Denial of Service attack with the impact being a full application crash, the severity for this is classified as High (7.5). Snyk is currently not aware of any fully-fledged PoCs or exploits in circulation. CVE-2021-45105 has been issued, and a new fixed version (2.17) has been published by Apache which we recommend upgrading to.
We have published an initial blog on the Log4j exploit and a followup blog with a second detection method for detecting the first stage of exploits occurring over LDAP. Today, we will discuss a third detection method, this one focused on the second-stage download that happens after the first stage completes. In this case, the JVM will download additional Java code payloads over HTTP.
There's little question that you've already heard about the recently discovered security flaw related to Log4j, a widely used Java library for logging error messages in applications. The vulnerability enables a threat actor to remotely execute commands via remote code execution (RCE) on nearly any machine using Log4j. But it's also important to cut through all of the noise to truly understand the implications of the Log4j and what organizations can do to combat it.
