Threatline

Log4j RCE: Emergency patch issued to plug critical auth-free code execution hole in widely used logging utility

Updated An unauthenticated remote code execution vulnerability in Apache's Log4j Java-based logging tool is being actively exploited, researchers have warned after it was used to execute code on Minecraft servers. The vuln is being tracked as CVE-2021-44228 and affects versions of Log4j before 2.14.1. The Apache Foundation published a patch for the critical-rated vuln earlier today. Its patch notes confirmed: "An attacker who can control log messages or log message parameters can execute arbitrary code loaded from LDAP servers when message lookup substitution is enabled." Immersive Labs' application security specialist Sean Wright told The Register that while immediate patches are available, it may be better to mitigate now and wait for a stable candidate. "While there are release candidates for the patches, they are not stable releases and can carry their own risks, so apply the temporary remediation until you can apply the patch from a stable version." "So although Apache Struts may depend on a specific version of Log4j when users create their applications they frequently change the versions to meet their requirements. So those frameworks are not at immediate risk but their users would be."