Welcome to an in-depth look at CVE-2022-29599, a shell injection vulnerability identified in Apache Maven's maven-shared-utils component. This particular vulnerability exists in versions of maven-shared-utils prior to 3.3.3, and specifically affects the Commandline class where the class fails to properly escape double-quoted strings.

This post will detail the code snippets that demonstrate how the vulnerability occurs and showcase how an attacker could potentially exploit this flaw. We will also provide links to the original CVE record and any relevant references that may help in understanding and mitigating the vulnerability.

Overview

The Apache Maven project is widely used by developers as a build automation tool to manage project dependencies and to compile and test projects. The maven-shared-utils component is a common library that provides various utilities for different aspects of Apache Maven. It also contains the Commandline class, which is responsible for handling command execution within the Maven environment.

The vulnerability arises when the Commandline class emits double-quoted strings without proper escaping. An attacker could potentially inject malicious shell commands, leading to a shell injection attack.

Code Snippet

Below, we'll take a look at the source code for the vulnerable Commandline class as it appeared before version 3.3.3. The following snippet demonstrates how the class fails to escape double-quoted strings properly:

private static final class QuotedStringTokenizer {
    //...

    private String addQuotesIfNeeded(String token) {
        if (token != null && needQuotes(token)) {
            token = '\"' + token + '\"';
        }
        return token;
    }

    private boolean needQuotes(String token) {
        return token.indexOf(' ') != -1 || token.indexOf('\\') != -1 || token.indexOf('"') != -1; 
    }

    //...
}

Exploit Details

An attacker could exploit this vulnerability by crafting a malicious double-quoted string that contains shell commands. In a scenario where the attacker has access to a Maven project's configuration, they could alter the project's configuration file (e.g., pom.xml) and insert a malicious double-quoted string, which may lead to shell command execution when the Commandline class processes the configuration data.

For instance, an attacker could set a value in the Maven project configuration that looks like this

<property>
  <property.name>"value_with_shell_command";shell_command_here</property.name>
</property>

When the Commandline class processes this data, it will not escape the double-quotes properly and may allow the malicious shell command to be executed.

Mitigation and Fixes

To address this vulnerability, developers using maven-shared-utils should upgrade to version 3.3.3, where the Commandline class has been patched to properly escape double-quoted strings. The complete fix and changes can be viewed in the related Git commit here: https://github.com/apache/maven-shared-utils/commit/3f9a28aeebece7b1872dbdcd93508486cd2a4f74.

1. CVE Record: https://nvd.nist.gov/view/vuln/detail?vulnId=CVE-2022-29599

2. Apache Maven Shared Utils GitHub Repository: https://github.com/apache/maven-shared-utils

Closing Thoughts

In conclusion, CVE-2022-29599 highlights the importance of properly escaping input data to avoid potential security risks. Developers leveraging Apache Maven's maven-shared-utils should be aware of this vulnerability and update to version 3.3.3 or later to mitigate the risk of a shell injection attack. As always, maintaining vigilance and staying up-to-date with the latest security patches is essential for keeping our codebase and infrastructure secure from emerging threats.

Timeline

Published on: 05/23/2022 11:16:00 UTC
Last modified on: 08/29/2022 15:15:00 UTC