A critical vulnerability in the popular log4j library is currently being actively targeted on a broad global scale and possibly exploited based on advisories from multiple CERTs and vendors: CISA, Apache, etc. This Java library is integrated into many IT and DevOps tooling and workflows. On Dec 10, 2021, Apache released version 2.15.0, fixing CVE-2021-44228 (dubbed Log4Shell) an RCE with a maximum CVSSv3 score of 10.
Earlier today, a serious flaw was discovered in the widely used Java logging library Apache Log4j. The vulnerability, ‘Log4Shell,’ was first identified by users of a popular Minecraft forum and was apparently disclosed to the Apache Foundation by Alibaba Cloud security researchers on Nov. 24, 2021. The vulnerability has the potential to allow unauthenticated remote code execution (RCE) on nearly any machine using Log4j.
Log4j zero-day vulnerability is flooding the security updates/news everywhere. This issue has been named Log4shell and assigned CVE-2021-44228 (still awaiting analysis at the time of writing).
Apache has released version 2.16.0, which completely removes support for Message Lookups and disables JNDI by default. CrowdStrike has identified a malicious Java class file hosted on infrastructure associated with a nation-state adversary. The Java code is used to download known instances of adversary-specific tooling and is likely to be used in conjunction with the recently disclosed Log4Shell exploit (CVE-2021-44228).
A previously unknown zero-day vulnerability in Log4j 2.x has been reported on December 9, 2021. If your organization deploys or uses Java applications or hardware running Log4j 2.x your organization is likely affected.
To understand how Elastic is currently assessing internal risk of this vulnerability in our products please see the advisory here.
Authors and Contributors: As always, security at Splunk is a family business. Credit to authors and collaborators: Ryan Kovar, Shannon Davis, Marcus LaFerrera, John Stoner, James Brodsky, Dave Herrald, Audra Streetman, Johan Bjerke, Drew Church, Mick Baccio, Lily Lee, Tamara Chacon, Ryan Becwar. If you want just to see how to find detections for the Log4j 2 RCE, skip down to the “detections” sections.
Today (Dec.10, 2021), a new, critical Log4j vulnerability was disclosed: Log4Shell. This vulnerability within the popular Java logging framework was published as CVE-2021-44228, categorized as Critical with a CVSS score of 10 (the highest score possible). The vulnerability was discovered by Chen Zhaojun from Alibaba’s Cloud Security team. All current versions of log4j2 up to 2.14.1 are vulnerable. You can remediate this vulnerability by updating to version 2.15.0 or later.
