Log4shell command use

Introduction

snyk log4shell is a Snyk CLI command, that helps find traces of the log4j library that are affected by the Log4Shell vulnerability (CVE-2021-44228), even if this library is not declared in the manifest files (such as pom.xml or build.gradle).

This command tests your built project and third-party applications, and it is complementary to the snyk test and snyk test --scan-all-unmanaged commands.

Read more about the Log4Shell vulnerability in the Snyk VulnDB entry.

To test Java projects using their package manager manifest files, see Options for Maven projects and Options for Gradle projects in the CLI test command help.

To learn more about the snyk test --scan-all-unmanaged, see the Maven options section of the CLI reference.

Usage

Use snyk log4shell to scan a Java project, to see if the project includes:

• Any .jar or .war files with a vulnerable version of log4j.

• Any files that are known to be present in a vulnerable version of the log4j library. Such a finding indicates that it is possible the whole log4j is included.

How to run

1. Install the latest version of the Snyk CLI - see Install the Snyk CLI.

2. Make sure you have built the project.

3. Navigate to the project directory to scan.

4. Enter snyk log4shell. Note: this command does not require (nor support) any additional arguments.

Scan results

Results appear after the scan finishes.

For example:

$ snyk log4shell
Please note this command is for already built artifacts. To test source code use `snyk test`.

Results:
A vulnerable version of log4j was detected: 
         demo-0.0.1-SNAPSHOT/WEB-INF/lib/log4j-core-2.14.1.jar
         demo-0.0.1-SNAPSHOT.war/WEB-INF/lib/log4j-core-2.14.1.jar
         demo-0.0.1-SNAPSHOT.war.original/WEB-INF/lib/log4j-core-2.14.1.jar

 We highly recommend fixing this vulnerability. If it cannot be fixed by upgrading, see mitigation information here:
        - https://security.snyk.io/vuln/SNYK-JAVA-ORGAPACHELOGGINGLOG4J-2314720
        - https://snyk.io/blog/log4shell-remediation-cheat-sheet/

If no traces of a vulnerable log4j library are found, the results show this:

$ snyk log4shell
Please note this command is for already built artifacts. To test source code use `snyk test`.

Results:
No known vulnerable version of log4j was detected

Fix advice

For more details about fixing the affected packages, see the Snyk Log4Shell fix cheatsheet.

Limitations

• The Snyk CLI compares file signatures to a database of known files. If the Log4Shell vulnerability is fixed in a different way from updating the log4j library, the library is still reported in the results.

• If the source code of the log4j library has been modified, it is detected.