CVE-2024-50379: Tomcat Vulnerability & Fix Guide

by Pedro Alvarez 49 views

Hey guys! Let's dive into a serious security issue that has been identified in the tomcat-embed-core-8.5.11.jar library. This article will break down the CVE-2024-50379 vulnerability, its implications, and how to address it. We'll cover everything in a way that's easy to understand, even if you're not a security expert. So, buckle up, and let's get started!

Understanding CVE-2024-50379

Let's talk about CVE-2024-50379, a critical severity vulnerability that affects the tomcat-embed-core-8.5.11.jar library. This vulnerability is a Time-of-check Time-of-use (TOCTOU) Race Condition that occurs during JSP compilation in Apache Tomcat. Now, that might sound like a mouthful, but let's break it down.

What is tomcat-embed-core-8.5.11.jar?

First off, tomcat-embed-core-8.5.11.jar is a core component of the Apache Tomcat implementation. Tomcat, as many of you probably know, is a widely-used open-source web server and servlet container. This particular library is crucial for embedding Tomcat within applications, making it a key part of many Java-based web projects. This library can be found on the library's home page at http://tomcat.apache.org/.

The Vulnerability: TOCTOU Race Condition

The heart of the issue is a Time-of-check Time-of-use (TOCTOU) Race Condition. This type of vulnerability arises when a program checks the state of a resource (like a file) and then uses that resource, but the state changes between the check and the use. Imagine a scenario where Tomcat checks if a file is safe to compile, and then, before it actually compiles the file, an attacker changes it to include malicious code. That's essentially what's happening here.

This vulnerability specifically affects systems with case-insensitive file systems when the default servlet is enabled for write – a configuration that isn't the default but can be set up. In such cases, an attacker could exploit this race condition to achieve Remote Code Execution (RCE).

Affected Versions

This vulnerability impacts several versions of Apache Tomcat:

  • From 11.0.0-M1 through 11.0.1
  • From 10.1.0-M1 through 10.1.33
  • From 9.0.0.M1 through 9.0.97

If your project uses any of these versions, it’s crucial to take action.

Why is this critical?

So, why is this considered a critical vulnerability? Well, Remote Code Execution (RCE) means an attacker can run arbitrary code on your server. This could lead to a complete compromise of your system, including data theft, service disruption, or even using your server as a launchpad for further attacks. The severity is high because the attack vector is network-based, the complexity is low, and no privileges or user interaction are required. This makes it relatively easy for an attacker to exploit.

Technical Details and CVSS 3 Score

Let's break down the technical aspects and the CVSS 3 score to understand the severity and potential impact of the CVE-2024-50379 vulnerability in tomcat-embed-core-8.5.11.jar. This will help you grasp the seriousness of the issue and why immediate action is necessary.

CVSS 3 Score: 9.8 (Critical)

The CVSS (Common Vulnerability Scoring System) provides a standardized way to assess the severity of security vulnerabilities. CVE-2024-50379 has a CVSS 3 score of 9.8, which is considered critical. This high score indicates a severe risk that needs urgent attention. Let's dive into the metrics that contribute to this score.

Base Score Metrics

The base score is composed of several metrics that describe the intrinsic characteristics of the vulnerability. These metrics are divided into Exploitability Metrics and Impact Metrics.

Exploitability Metrics

These metrics describe how easily the vulnerability can be exploited.

  • Attack Vector: Network This means the vulnerability can be exploited over a network, allowing attackers to target your system remotely. This broadens the attack surface significantly.
  • Attack Complexity: Low The complexity of exploiting this vulnerability is low, meaning it doesn't require specialized skills or conditions. This makes it easier for attackers to exploit.
  • Privileges Required: None No privileges are required to exploit this vulnerability. An attacker doesn't need to have any legitimate access to the system, making it more dangerous.
  • User Interaction: None No user interaction is required. The attack can be carried out without any action from the user, such as clicking a link or opening a file. This makes it stealthier and more likely to succeed.
  • Scope: Unchanged The vulnerability affects the Tomcat server itself, meaning the attacker can gain control over the server process but not necessarily the entire system.

Impact Metrics

These metrics describe the potential impact of a successful exploit.

  • Confidentiality Impact: High A successful exploit can lead to a complete loss of confidentiality. Attackers can access sensitive data, such as usernames, passwords, and proprietary information.
  • Integrity Impact: High The integrity of the system is severely compromised. Attackers can modify system files, inject malicious code, or alter data, leading to untrustworthy systems.
  • Availability Impact: High The availability of the system is critically impacted. Attackers can cause a denial of service (DoS), making the system unavailable to legitimate users.

Understanding the Implications

The combination of these metrics paints a clear picture: CVE-2024-50379 is a severe vulnerability. The low attack complexity and the fact that no privileges or user interaction are required make it highly exploitable. The potential for complete loss of confidentiality, integrity, and availability means the consequences of a successful exploit can be devastating.

For more information on CVSS3 Scores, you can click here. This will provide you with a deeper understanding of how these scores are calculated and what they mean for your system's security.

Identifying the Vulnerable Library

Okay, so we know there's a problem. But how do you find out if your project is using the vulnerable tomcat-embed-core-8.5.11.jar library? Don't worry; we've got you covered. Let's walk through the steps to identify if your application is at risk.

Checking Dependency Hierarchy

One of the most effective ways to identify the vulnerable library is by examining your project's dependency hierarchy. If you're using a build tool like Maven or Gradle, this process is relatively straightforward.

Maven

If you're using Maven, you can use the mvn dependency:tree command. This command will generate a tree-like structure of all your project's dependencies, including transitive dependencies (the dependencies of your dependencies). Look for tomcat-embed-core in the output. If you see version 8.5.11, you're vulnerable.

For example, the dependency hierarchy might look something like this:

spring-boot-starter-web-1.5.2.RELEASE.jar (Root Library)
  +- spring-boot-starter-tomcat-1.5.2.RELEASE.jar
  |  \- tomcat-embed-core-8.5.11.jar (Vulnerable Library)

In this case, you can see that tomcat-embed-core-8.5.11.jar is a transitive dependency of spring-boot-starter-tomcat, which is itself a dependency of spring-boot-starter-web. This means you need to update your dependencies to eliminate the vulnerable library.

Gradle

For Gradle users, you can use the gradle dependencies command. This will output a list of all dependencies in your project. Again, look for tomcat-embed-core and check its version. If it's 8.5.11, you need to take action.

The output might look similar to this:

runtimeClasspath - Runtime classpath for source set 'main'.
+--- org.springframework.boot:spring-boot-starter-web:1.5.2.RELEASE
|    +--- org.springframework.boot:spring-boot-starter-tomcat:1.5.2.RELEASE
|    |    +--- org.apache.tomcat.embed:tomcat-embed-core:8.5.11

Checking your pom.xml or build.gradle

Another way to identify the vulnerability is by directly inspecting your project's build configuration files.

pom.xml (Maven)

Open your pom.xml file and look for the tomcat-embed-core dependency. If you find it, check the version. If it's 8.5.11, you need to update it.

<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-core</artifactId>
    <version>8.5.11</version> <!-- Vulnerable Version -->
</dependency>

build.gradle (Gradle)

Open your build.gradle file and look for the tomcat-embed-core dependency in the dependencies block. Check the version and update if necessary.

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-web:1.5.2.RELEASE'
    implementation 'org.springframework.boot:spring-boot-starter-tomcat:1.5.2.RELEASE'
    // Check transitive dependencies for tomcat-embed-core
}

Automated Scanning Tools

For larger projects, manually checking dependencies can be time-consuming and error-prone. Consider using automated scanning tools like OWASP Dependency-Check, Snyk, or Sonatype Nexus Lifecycle. These tools can automatically scan your project's dependencies and identify known vulnerabilities, including CVE-2024-50379.

Example: t-vault Project

In the example provided, the vulnerability was found in the t-vault project (https://github.com/billmcchesney1/t-vault/commit/0f3cd3fd3c5ad14d3c051359006dda186a4202f1). The vulnerable library was located at /home/wss-scanner/.m2/repository/org/apache/tomcat/embed/tomcat-embed-core/8.5.11/tomcat-embed-core-8.5.11.jar and was identified through the dependency hierarchy.

By following these steps, you can effectively identify if your project is using the vulnerable tomcat-embed-core-8.5.11.jar library and take the necessary steps to mitigate the risk.

Suggested Fix: Upgrade Tomcat

Alright, guys, we've identified the vulnerability, understood its implications, and pinpointed how to find it in our projects. Now, let's talk about the most important part: how to fix it! The suggested fix for CVE-2024-50379 in tomcat-embed-core-8.5.11.jar is straightforward: upgrade to a patched version of Tomcat. Here’s a detailed guide on how to do that.

The Solution: Upgrade Tomcat Versions

The Apache Tomcat team has released updated versions that address this vulnerability. The fix involves upgrading to one of the following versions:

  • 11.0.2 or later
  • 10.1.34 or later
  • 9.0.98 or later

These versions include the necessary patches to mitigate the TOCTOU race condition, effectively closing the security gap. It's crucial to upgrade to one of these versions to protect your application.

Why Upgrade?

Upgrading Tomcat isn't just about fixing this specific vulnerability; it's also about maintaining the overall security and stability of your application. Newer versions often include performance improvements, bug fixes, and additional security enhancements. Staying up-to-date with the latest releases is a best practice for any software project.

How to Upgrade

The process for upgrading Tomcat depends on how you've integrated it into your project. Here are the most common scenarios and how to handle them:

Standalone Tomcat Installation

If you're running Tomcat as a standalone server, the upgrade process typically involves downloading the new version, stopping the old server, replacing the installation directory, and starting the new server. Here’s a step-by-step guide:

  1. Download the new version: Go to the Apache Tomcat website (https://tomcat.apache.org/) and download the appropriate version (11.0.2, 10.1.34, or 9.0.98) for your environment.
  2. Stop the current Tomcat server: Use the shutdown script or command for your operating system.
  3. Backup your configuration: Before replacing the installation, make a backup of your conf directory. This will allow you to restore your settings if anything goes wrong.
  4. Replace the installation directory: Delete the contents of your current Tomcat installation directory and extract the new version into the same location.
  5. Restore your configuration: Copy the backed-up configuration files (especially server.xml, web.xml, and any custom context files) into the new conf directory.
  6. Start the new Tomcat server: Use the startup script or command for your operating system.
  7. Test your application: Ensure your application is running correctly on the upgraded Tomcat version.

Embedded Tomcat in Spring Boot

If you're using Spring Boot, upgrading Tomcat is usually a matter of updating your Spring Boot version. Spring Boot manages the Tomcat dependency for you, so upgrading Spring Boot will bring in the updated Tomcat version. Here’s how:

  1. Update Spring Boot version: Open your pom.xml (Maven) or build.gradle (Gradle) file and update the Spring Boot version to a version that includes the patched Tomcat version. You can find the Spring Boot release notes to see which versions include the necessary Tomcat updates. For example, in Maven:
    <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.3.RELEASE</version> <!-- Update this version -->
    <relativePath/> <!-- lookup parent from repository -->
</parent>
    Or in Gradle:
    dependencies {
    implementation('org.springframework.boot:spring-boot-starter-web:1.5.3.RELEASE') // Update this version
}
  2. Rebuild your project: After updating the version, rebuild your project to pull in the new dependencies.
  3. Test your application: Ensure your application is running correctly with the updated Spring Boot and Tomcat versions.

Other Environments

If you're using Tomcat in a different environment, consult the documentation for your specific setup. The general principle remains the same: upgrade to a patched version of Tomcat.

Fix Resolution Details

The specific fix resolution includes upgrading the following components:

  • org.apache.tomcat:tomcat-catalina to version 9.0.98, 10.1.34, or 11.0.2
  • org.apache.tomcat.embed:tomcat-embed-core to version 9.0.98, 10.1.34, or 11.0.2

These updates ensure that the vulnerability is fully addressed across all relevant Tomcat components.

Additional Information

For more details on the fix and the vulnerability, you can refer to the Apache Tomcat security advisories and the CVE database. The origin of the fix can be found at https://tomcat.apache.org/security-11.html, which provides comprehensive information on security-related updates for Tomcat.

By following these steps and upgrading to a patched version of Tomcat, you can effectively mitigate the CVE-2024-50379 vulnerability and keep your application secure. Don't wait – take action now to protect your system!

Conclusion

So, there you have it, folks! We've taken a deep dive into CVE-2024-50379, a critical vulnerability affecting tomcat-embed-core-8.5.11.jar. We've covered what the vulnerability is, why it's so serious, how to identify if your project is affected, and, most importantly, how to fix it. This vulnerability, a Time-of-check Time-of-use (TOCTOU) Race Condition, can lead to Remote Code Execution (RCE) on systems with case-insensitive file systems when the default servlet is enabled for write.

Key Takeaways

Let's recap the key takeaways:

  • CVE-2024-50379 is critical: With a CVSS 3 score of 9.8, this vulnerability poses a severe risk to your system. The potential impact includes complete loss of confidentiality, integrity, and availability.
  • Affected versions: This vulnerability affects Apache Tomcat versions 11.0.0-M1 through 11.0.1, 10.1.0-M1 through 10.1.33, and 9.0.0.M1 through 9.0.97.
  • Identify the vulnerability: Use dependency analysis tools or manually check your pom.xml or build.gradle files to identify if your project uses the vulnerable tomcat-embed-core-8.5.11.jar library.
  • Upgrade is essential: The fix is to upgrade to Apache Tomcat versions 11.0.2, 10.1.34, or 9.0.98, which include the necessary patches.
  • Stay updated: Regularly update your dependencies and use automated scanning tools to stay ahead of potential vulnerabilities.

The Importance of Prompt Action

In the world of cybersecurity, time is of the essence. The longer a vulnerability remains unpatched, the greater the risk of exploitation. Attackers are constantly scanning for vulnerable systems, and CVE-2024-50379 is a prime target due to its severity and ease of exploitation. Therefore, it's crucial to take prompt action and upgrade your Tomcat installation as soon as possible.

Best Practices for Security

Addressing CVE-2024-50379 is a critical step, but it's also essential to adopt broader security best practices to protect your applications and systems. Here are a few recommendations:

  • Regularly update dependencies: Keep your libraries and frameworks up-to-date to benefit from security patches and bug fixes.
  • Use automated scanning tools: Integrate tools like OWASP Dependency-Check, Snyk, or Sonatype Nexus Lifecycle into your CI/CD pipeline to automatically identify vulnerabilities.
  • Follow security advisories: Subscribe to security mailing lists and monitor advisories from Apache Tomcat and other vendors to stay informed about potential threats.
  • Implement security testing: Conduct regular security testing, including penetration testing and vulnerability assessments, to identify and address weaknesses in your applications.
  • Principle of Least Privilege: Ensure that users and processes have only the necessary privileges to perform their tasks. This can limit the potential impact of a successful attack.

Final Thoughts

Security is a continuous process, not a one-time fix. By staying informed, taking proactive measures, and following best practices, you can significantly reduce your risk and protect your systems from potential threats. So, guys, let's make sure we're doing everything we can to keep our applications secure! Remember to upgrade your Tomcat versions, and stay vigilant in the face of evolving security challenges.