Security | Threat Detection | Cyberattacks | DevSecOps | Compliance

It’s the last Patch Tuesday update of 2021, and as with many other updates this year, this month’s list includes important ones — among them a zero-day (CVE-2021-43890 in AppX installer), multiple critical vulnerabilities and a variety of attack types utilized in several Microsoft product families — highlighting once again that patching and prioritization are prominent programs SecOps staff must regularly implement to keep adversaries from infiltrating their organizations’

For more information on how to respond to the Log4j vulnerabilities using Splunk products, please see our Log4Shell response overview page. Like most cybersecurity teams, the Splunk Threat Research Team (STRT) has been heads-down attempting to understand, simulate, and detect the Log4j attack vector. This post shares detection opportunities STRT found in different stages of successful Log4Shell exploitation.

A critical vulnerability has been recently discovered in the Apache Log4j Java logging library (CVE-2021-44228), a library used in many client and server applications. The Log4j library is commonly included in Java based software including multiple Apache frameworks such as Struts2, Solr, Druid and Fink. The library provides enhanced logging functionality for Java applications and is commonly used in business system development.

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.

At Snyk we have some general points of principle that we use to help guide our security thinking and decision making. Firstly, it is always important to understand from whom we are protecting, as it has implications for how we need to act. As an example of this, if our artefact is a web server, then we need to protect it against untrusted users. Whilst if our artefact is encryption software, then we clearly need to protect it even from users with physical access to the system.

As security and development teams rushed to assess the now-notorious Log4Shell vulnerability published December 10 (CVE-2021-44228), another, more minor vulnerability was discovered in Log4j — CVE-2021-45046. To understand the newly-discovered vulnerability, it is important to get the full picture and background on the original Log4j issue.

Dec. 29: Updated to cover three additional CVEs: CVE-2021-4104, CVE-2021-44832, and CVE-2021-42550 (in logback as opposed to log4j). Dec. 22: A joint Cybersecurity Advisory was issued by multiple national cybersecurity agencies providing mitigation guidance on addressing vulnerabilities in Apache’s Log4j software library: CVE-2021-44228 (known as “Log4Shell”), CVE-2021-45046, and CVE-2021-45105. Dec. 17: Please note the emergency directive from CISA on Log4j.

Dec. 29: Updated to cover three additional CVEs: CVE-2021-4104, CVE-2021-44832, and CVE-2021-42550 (in logback as opposed to log4j). Dec. 22: A joint Cybersecurity Advisory was issued by multiple national cybersecurity agencies providing mitigation guidance on addressing vulnerabilities in Apache’s Log4j software library: CVE-2021-44228 (known as “Log4Shell”), CVE-2021-45046, and CVE-2021-45105. Dec. 17: Please note the emergency directive from CISA on Log4j.