Log4j is a popular Java-based logging utility widely used in many applications. Following the discovery of the Log4Shell vulnerability (CVE-2021-44228), it has become crucial to ensure that your system is running a secure version of Log4j. Checking the Log4j version on a Windows system can help identify outdated or vulnerable versions and ensure that proper updates are applied. This guide provides step-by-step instructions to check the Log4j version on Windows.
Why Check the Log4j Version?
- Security: Outdated versions of Log4j may contain vulnerabilities, such as Log4Shell, which can be exploited for remote code execution.
- Compatibility: Specific applications require particular versions of Log4j to function properly.
- Troubleshooting: Identifying the Log4j version helps diagnose and resolve potential issues with your application’s logging capabilities.
How to Check Log4j Version in Windows
Here are several methods to determine the installed version of Log4j on a Windows system:
1. Using the find Command to Locate Log4j Files
The first step is to locate where Log4j is installed on your system.
Steps:
1. Open the Command Prompt by typing cmd in the Start menu search bar and pressing Enter.
2. Use the following command to search for Log4j JAR files across your drives:
dir /s /p log4j*.jar
3. Note the paths where Log4j files are located. For example:
C:\Program Files\YourApp\lib\log4j-core-2.17.1.jar
2. Checking the Log4j Version Using the Command Line
Once the Log4j JAR files are located, you can use the jar command to inspect the version information.
Steps:
1. Ensure that Java is installed on your system. Open the Command Prompt and type:
java -version
If Java is not installed, download and install it from the official website.
2. Navigate to the directory containing the Log4j JAR file. Use the cd command:
cd C:\Program Files\YourApp\lib
3. Run the following command to extract the manifest file from the JAR:
jar -xf log4j-core-2.17.1.jar META-INF/MANIFEST.MF
4. Open the MANIFEST.MF file using a text editor (e.g., Notepad):
notepad META-INF/MANIFEST.MF
5. Look for the Implementation-Version entry, which specifies the Log4j version:
Implementation-Version: 2.17.1
3. Checking Log4j Version Programmatically
If you have access to the application source code or configuration, you can write a small Java program to programmatically check the Log4j version.
Code Example:
import org.apache.logging.log4j.util.PropertiesUtil;
public class Log4jVersionCheck {
public static void main(String[] args) {
System.out.println(“Log4j Version: ” + PropertiesUtil.class.getPackage().getImplementationVersion());
}
}
Steps:
1. Compile the code using javac:
javac Log4jVersionCheck.java
2. Run the program:
java Log4jVersionCheck
3. The program will print the Log4j version.
4. Using Third-Party Tools
Many applications bundle Log4j within their installation directories. Third-party tools like dependency analyzers or security scanners can help identify the Log4j version.
Recommended Tools:
- Dependency-Check: Scans dependencies in applications to detect vulnerable Log4j versions.
- Syft: A CLI tool for generating Software Bills of Materials (SBOM) and identifying Log4j components.
5. Verifying Package Details
If Log4j was installed using a package manager, check its version directly.
Steps:
1. Open PowerShell or Command Prompt.
2. Run the following command to list installed Java libraries (if applicable)
mvn dependency:tree | findstr log4j
This command works for Maven-based Java projects, showing the Log4j version in use.
Updating Log4j to a Secure Version
If your system is running a vulnerable version of Log4j, update it immediately to the latest secure release.
Steps to Update Log4j
- Download the latest version of Log4j from the official website.
- Replace the old JAR files (e.g., log4j-core-*.jar and log4j-api-*.jar) in your application’s lib directory with the updated versions.
- Restart the application to apply changes.
Conclusion
Checking the Log4j version on a Windows system is essential for maintaining application security and functionality. Whether you use command-line tools, programmatic methods, or third-party utilities, ensure that your Log4j version is up-to-date. Vulnerabilities like Log4Shell underscore the importance of staying proactive in managing software dependencies to protect against security risks.
