CVE-2021-31559 : Exploit Details and Defense Strategies

A crafted request bypasses S2S TCP Token authentication in Splunk Enterprise Indexer versions before 8.1.5 and 8.2.1. This impacts Indexers using TCPTokens but not Universal Forwarders.

Understanding CVE-2021-31559

This CVE involves a security vulnerability that allows crafted requests to bypass authentication mechanisms in certain versions of Splunk Enterprise.

What is CVE-2021-31559?

The vulnerability allows attackers to send specially crafted requests that bypass S2S TCP Token authentication, enabling them to write arbitrary events to an index in affected Splunk Enterprise versions.

The Impact of CVE-2021-31559

Exploiting this vulnerability can lead to unauthorized users injecting arbitrary events into the system, potentially compromising data integrity.

Technical Details of CVE-2021-31559

This section provides more technical insights into the vulnerability.

Vulnerability Description

The vulnerability arises from a flaw that allows crafted requests to evade authentication controls, impacting systems using TCPTokens in Splunk Enterprise.

Affected Systems and Versions

Splunk Enterprise Indexer versions before 8.1.5 and 8.2.1 are affected by this vulnerability when configured to utilize TCPTokens.

Exploitation Mechanism

Attackers can exploit this vulnerability by sending specially crafted requests that bypass the S2S TCP Token authentication, enabling them to write arbitrary events to the affected index.

Mitigation and Prevention

To protect systems from CVE-2021-31559, certain mitigation strategies can be implemented.

Immediate Steps to Take

Users should update Splunk Enterprise Indexer to version 8.2.1 or 8.1.5 to eliminate this vulnerability and prevent potential exploitation.

Long-Term Security Practices

Regularly monitor and update the Splunk Enterprise software to ensure that security patches are applied promptly, reducing the risk of exploitation.

Patching and Updates

Stay informed about security advisories and promptly install patches provided by Splunk to address known vulnerabilities.