(Written in Go because, you know, "write once, run anywhere.")

This is a simple tool that can be used to find vulnerable instances of log4j 1.x and 2.x (CVE-2019-17571, CVE-2021-44228) in installations of Java software such as web applications. JAR and WAR archives are inspected and class files that are known to be vulnerable are flagged. The scan happens recursively: WAR files containing WAR files containing JAR files containing vulnerable class files ought to be flagged properly.

This tool currently checks for known build artifacts that have been obtained through Maven. From-source rebuilds as they are done for Linux distributions may not be recognized.

$ ./log4j-vuln-scanner /path/to/app1 /path/to/app2 …

If class files indicating one of the vulnerabilities are found, messages like the following are printed to standard output:

./local-log4j-vuln-scanner - a simple local log4j vulnerability scanner

indicator for vulnerable component found in /path/to/vuln/log4shell-vulnerable-app-0.0.1-SNAPSHOT.war::WEB-INF/lib/log4j-core-2.14.1.jar (org/apache/logging/log4j/core/net/JndiManager$JndiManagerFactory.class): log4j 2.14.0-2.14.1
indicator for vulnerable component found in /path/to/vuln/log4shell-vulnerable-app-0.0.1-SNAPSHOT.war::WEB-INF/lib/log4j-core-2.14.1.jar (org/apache/logging/log4j/core/net/JndiManager.class): log4j 2.14.0-2.14.1
Scan finished

GNU General Public License, version 3

Hilko Bengen <[email protected]>