CVE-2022-25647: Google Gson Deserialization DoS Vulnerability

CVE-2022-25647 Overview

CVE-2022-25647 is an insecure deserialization vulnerability affecting the Google Gson library (com.google.code.gson:gson) in versions prior to 2.8.9. The vulnerability exists in the writeReplace() method within internal classes, which can be exploited to deserialize untrusted data. Successful exploitation of this vulnerability can lead to Denial of Service (DoS) attacks against applications using the affected library.

Google Gson is one of the most widely used Java libraries for JSON serialization and deserialization, making this vulnerability particularly impactful across the Java ecosystem. The vulnerability is network-exploitable without requiring authentication or user interaction, making it accessible to remote attackers.

Critical Impact

Applications using vulnerable versions of Google Gson are susceptible to DoS attacks through maliciously crafted serialized data, potentially causing service disruption and availability issues.

Affected Products

• Google Gson (versions before 2.8.9)
• Debian Linux (9.0, 10.0, 11.0)
• NetApp Active IQ Unified Manager (Linux, VMware vSphere, Windows)
• Oracle Financial Services Crime and Compliance Management Studio (8.0.8.2.0, 8.0.8.3.0)
• Oracle GraalVM Enterprise (20.3.6, 21.3.2, 22.1.0)
• Oracle Retail Order Broker (18.0, 19.1)

Discovery Timeline

• 2022-05-01 - CVE-2022-25647 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-25647

Vulnerability Analysis

This vulnerability is classified as CWE-502 (Deserialization of Untrusted Data). The flaw resides in the way Gson handles the writeReplace() method within its internal classes during the serialization/deserialization process.

In Java, the writeReplace() method is a special serialization hook that allows an object to nominate a replacement object to be serialized in its place. When Gson processes objects containing this method in internal classes, it can be manipulated to cause resource exhaustion or other DoS conditions.

The vulnerability can be exploited remotely over the network without requiring any privileges or user interaction, making it particularly dangerous for applications that process untrusted JSON input.

Root Cause

The root cause of this vulnerability lies in improper handling of the writeReplace() method within Gson's internal classes. When deserializing data, Gson did not adequately validate or restrict the behavior of objects using this serialization mechanism. This oversight allows an attacker to craft malicious payloads that, when processed by the Gson library, trigger resource exhaustion or other denial of service conditions.

The fix, implemented in version 2.8.9, addresses this by properly securing the internal class handling and preventing exploitation through the writeReplace() method.

Attack Vector

The attack exploits Gson's deserialization process by sending specially crafted serialized data to an application endpoint that processes JSON using a vulnerable version of Gson. The attack vector is network-based and does not require authentication.

An attacker can target any application that:

1. Uses Gson versions prior to 2.8.9
2. Accepts and deserializes external JSON input
3. Processes data through Gson's internal serialization mechanisms

When the vulnerable application processes the malicious payload, the writeReplace() method in internal classes is triggered in an uncontrolled manner, leading to resource exhaustion and denial of service.

The vulnerability manifests in Gson's internal class handling during deserialization. The writeReplace() method can be abused to create conditions that exhaust system resources. For detailed technical analysis, refer to the GitHub Gson Pull Request #1991 which contains the fix and associated commits.

Detection Methods for CVE-2022-25647

Indicators of Compromise

• Unusual memory consumption spikes in Java applications using Gson
• Application crashes or unresponsiveness during JSON processing operations
• Increased CPU utilization correlated with JSON deserialization activities
• Exception logs indicating serialization or deserialization failures in Gson classes

Detection Strategies

• Implement Software Composition Analysis (SCA) tools to identify vulnerable Gson versions (< 2.8.9) in your codebase
• Monitor application logs for exceptions related to Gson deserialization, particularly involving internal classes
• Deploy runtime application self-protection (RASP) solutions to detect anomalous deserialization behavior
• Use dependency scanning in CI/CD pipelines to flag vulnerable library versions before deployment

Monitoring Recommendations

• Enable verbose logging for JSON processing components to capture deserialization events
• Set up alerts for sudden increases in memory or CPU usage during JSON operations
• Monitor for application hangs or timeouts associated with user-submitted JSON data
• Implement health checks that can detect DoS conditions affecting application availability

How to Mitigate CVE-2022-25647

Immediate Actions Required

• Upgrade Google Gson to version 2.8.9 or later immediately
• Audit all applications and dependencies to identify usage of vulnerable Gson versions
• Implement input validation and size limits on JSON payloads processed by applications
• Consider implementing rate limiting on endpoints that accept JSON input

Patch Information

The vulnerability has been addressed in Google Gson version 2.8.9. The fix is documented in GitHub Gson Pull Request #1991 and the associated commits.

For Oracle products, refer to the Oracle Critical Patch Update Advisory July 2022 for specific patch information.

Debian users should consult the Debian Security Advisory DSA-5227 for distribution-specific patches.

NetApp customers should review the NetApp Security Advisory NTAP-20220901-0009 for guidance on affected products.

Workarounds

• Restrict Gson deserialization to known, trusted data sources only
• Implement strict input validation on all JSON input before processing
• Use allowlisting for expected data types during deserialization
• Deploy web application firewalls (WAF) to filter potentially malicious JSON payloads
• Consider using alternative JSON libraries with stronger security controls if immediate patching is not possible

# Maven: Update Gson dependency to patched version
# In pom.xml, update the Gson version:
# <dependency>
#     <groupId>com.google.code.gson</groupId>
#     <artifactId>gson</artifactId>
#     <version>2.8.9</version>
# </dependency>

# Gradle: Update Gson dependency
# In build.gradle:
# implementation 'com.google.code.gson:gson:2.8.9'

# Verify current Gson version in Maven project
mvn dependency:tree | grep gson

# Verify current Gson version in Gradle project
gradle dependencies | grep gson