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.
We recently discussed some methods for detecting the Log4j exploit, and we’ve now developed another method that everyone running Zeek® or a Corelight sensor can use. Our new approach is based on the rarity of legitimate downloads of Java via LDAP. Zeek does not currently have a native LDAP protocol analyzer (though one is available if you are running Spicy). This will not stop you from detecting this exploit downloading Java over LDAP, though. To see how, read on.
In quick succession in December, The Apache Software Foundation released information on two critical vulnerabilities in its Log4j Java-based library. The first vulnerability CVE-2021-44228, also known as Log4Shell or LogJam, was reported as an unauthenticated remote code execution (RCE) vulnerability. By exploiting how the library logs error messages, it could lead to a complete system takeover.
The United States Department of Homeland Security (DHS) is inviting security researchers to uncover vulnerabilities and hack into its systems, in an attempt to better protect itself from malicious attacks.
