Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')

Summary

Arbitrary Code Execution vulnerability in "JaninoEventEvaluator" by QOS.CH logback in Java applications, allows attackers to execute arbitrary code by compromising an existing logback configuration file or by injecting an environment variable before program execution. Malicious logback configuration files can allow the attacker to execute arbitrary code using the "JaninoEventEvaluator" extension. A successful attack requires the user to have write access to a configuration file. Alternatively, the attacker could inject a malicious environment variable pointing to a malicious configuration file. In both cases, the attack requires existing privilege. This issue affects ch.qos.logback:logback-classic and ch.qos.logback:logback-core packages versions through 1.3.14, and 1.4.0 through 1.5.12.