A major vulnerability in the code of Java software library used for logging has recently been discovered. This vulnerability, commonly known as log4shell, is present in Apache log4j, a Java-based library widely used for logging in software and applications.
Common Vulnerability Exposure discovered in December 2021, CVE-2021-44228, a reference method for publicly known information-security vulnerabilities and exposures, affects Java’s Apache versions 2.0 to 2.15 which has been classified as critical. The log4shell vulnerability allows attackers to execute code remotely, compromise systems and disclose information. Attackers can exploit this vulnerability in combination with other methods to widen and sharpen their attacks.
The logging library Log4j is an extensively used framework by applications and services across the world. The CVE-2021-44228 vulnerability is exploited by sending a specific Java Naming and Directory Interface (JNDI) string into the Log4J software and in turn trigger the execution of malicious code in the directory services such as Library Directory Application Protocol (LDAP), hence compromising these systems.
- CVE-2021-45046: The remote code execution allows an attacker to insert a malicious Java class file location into the directory data and execute it on the system to compromise it.
- CVE-2021-45105: Denial of Service (DOS) allows an infinite recursion to be triggered on the vulnerable application to exhaust the system’s resources and severely affecting the services.
- Follow recommended security best practices and upgrade to the latest Log4j versions recommended by official Apache community website or apply corresponding security patches recommended by technology vendors.
- Protect the public-facing services that have Log4j capabilities
- Make use of Web Application Firewalls with up-to-date security engines
- Ensure proactive monitoring via specialised security service providers and contact our Security Operations Centre (SOC) in response to alerts on the related systems and devices.
- Update Response and Remediation procedures for such vulnerabilities in your Business Continuity Plan