CVE-2021-29485 : What You Need to Know

Ratpack is a toolkit for creating web applications. A vulnerability (CVE-2021-29485) exists in versions prior to 1.9.0 that could allow a remote attacker to execute malicious code by exploiting the Java deserialization gadget chain in the Ratpack session store. Ratpack 1.9.0 has introduced strict mitigation mechanisms. Read on to understand the impact, technical details, and mitigation steps for this vulnerability.

Understanding CVE-2021-29485

This section delves into the specifics of the CVE-2021-29485 vulnerability in Ratpack.

What is CVE-2021-29485?

In versions of Ratpack before 1.9.0, a malicious actor could achieve Remote Code Execution (RCE) through a Java deserialization gadget chain targeting the Ratpack session store. Applications not using Ratpack's session mechanism are not susceptible. The 1.9.0 version introduces an allow-list feature to mitigate this vulnerability.

The Impact of CVE-2021-29485

The vulnerability has a CVSS base score of 9.9, categorizing it as critical. It could result in high confidentiality, integrity, and availability impacts. The attack vector is through the network, with low complexity and privileges required, affecting systems that do not use the new allow-list mechanism.

Technical Details of CVE-2021-29485

Explore the technical aspects of the CVE-2021-29485 vulnerability.

Vulnerability Description

The vulnerability arises from a flaw in the Java deserialization gadget chain used in Ratpack's session storage, enabling remote code execution by malicious actors.

Affected Systems and Versions

Systems running Ratpack versions below 1.9.0 are vulnerable to this exploit. Applications using Ratpack's session mechanism without the new allow-list are at risk.

Exploitation Mechanism

Attackers can exploit this vulnerability by leveraging a crafted Java deserialization gadget chain against Ratpack's application session store.

Mitigation and Prevention

Discover the steps to mitigate and prevent the CVE-2021-29485 vulnerability.

Immediate Steps to Take

Users of vulnerable versions should minimize attacker access to the session data store. Alternatively, implement the new allow-list mechanism in Ratpack 1.9.0 or backport it manually for earlier versions.

Long-Term Security Practices

Maintain secure coding practices, monitor for updates, and regularly test your applications for vulnerabilities to enhance long-term security.

Patching and Updates

Ensure that your Ratpack framework is updated to version 1.9.0 or later to implement the necessary security mechanisms and prevent exploitation of this vulnerability.