Apache Log4j Vulnerability Guidance

The Cybersecurity & Infrastructure Security Agency (CISA) and its partners issued guidance and multiple resources to mitigate the CVE-2021-44228 (known as “Log4Shell”), CVE-2021-45046, and CVE-2021-45105 in Apache’s Log4j software library vulnerability. Log4j is broadly used in a variety of consumer and enterprise services, websites, and applications—as well as in operational technology products—to log security and performance information. The vulnerability allows an attacker who can control log messages or log message parameters to execute arbitrary code loaded from LDAP/RMI servers when message lookup substitution is enabled. The following mitigations are recommended:

• Discover all internet-facing assets that allow data inputs and use Log4j Java library anywhere in the stack.
• Update or isolate affected assets. Assume compromise, identify common post-exploit sources and activity, and hunt for signs of malicious activity.
• Monitor for odd traffic patterns (e.g., JNDI LDAP/RMI outbound traffic, DMZ systems initiating outbound connections).
• Follow CISA’s guidance on Mitigating Log4Shell and Other Log4j-Related Vulnerabilities
• Review CISA’s Known Exploited Vulnerabilities Catalog to see if your organization systems are affected.
• Recommend using GitHub’s CERT/CC's CVE-2021-44228_scanner to detect vulnerable applications.
• Monitor the Apache Log4j Security Vulnerabilities Webpage for updates and mitigation guidance.
• Review the Electricity Information Sharing and Analysis Center (E‐ISAC) alerts related to Log4j.