CVE-2021-31810 : What You Need to Know

An issue was discovered in Ruby versions 2.6.7 through 3.0.1. A malicious FTP server can exploit a vulnerability in Net::FTP, potentially enabling unauthorized access to private services.

Understanding CVE-2021-31810

This CVE highlights a security vulnerability in Ruby that allows a malicious FTP server to manipulate the PASV response to extract sensitive information from a target system.

What is CVE-2021-31810?

The CVE-2021-31810 vulnerability affects Ruby versions 2.6.7 through 3.0.1. It enables a malicious FTP server to trick Net::FTP into connecting back to a specified IP address and port, facilitating unauthorized access to private services.

The Impact of CVE-2021-31810

Exploitation of this vulnerability could lead to unauthorized disclosure of private services, enabling attackers to conduct port scans and extract service banners, potentially compromising the target system's security.

Technical Details of CVE-2021-31810

This section delves into the specifics of the vulnerability, its affected systems, versions, and exploitation methods.

Vulnerability Description

The flaw allows a malicious FTP server to manipulate Net::FTP, forcing it to connect back to a specific IP address and port, potentially enabling unauthorized access to private services.

Affected Systems and Versions

Ruby versions 2.6.7 through 3.0.1 are impacted by this vulnerability, exposing systems that utilize the Net::FTP library to potential exploitation.

Exploitation Mechanism

By manipulating the PASV response, a malicious FTP server can coerce Net::FTP into establishing connections back to an attacker-controlled IP address and port, facilitating unauthorized access to private services.

Mitigation and Prevention

In this section, we outline immediate steps to mitigate the risks posed by CVE-2021-31810 and emphasize long-term security practices.

Immediate Steps to Take

Users are advised to update Ruby to a patched version to mitigate the vulnerability. Additionally, network segmentation and access controls can help limit exposure to potential attacks.

Long-Term Security Practices

Regularly updating software, implementing network monitoring solutions, and following security best practices can bolster overall cybersecurity posture.

Patching and Updates

Staying informed about security advisories and promptly applying patches for affected software can help prevent exploitation of known vulnerabilities.