CVE-2021-39249 : Exploit Details and Defense Strategies

Invision Community (aka IPS Community Suite or IP-Board) before 4.6.5.1 allows reflected XSS due to predictability of uploaded file names.

Understanding CVE-2021-39249

Invision Community software versions prior to 4.6.5.1 are vulnerable to reflected XSS attacks.

What is CVE-2021-39249?

This CVE identifies a security vulnerability in Invision Community (IP.Board) that enables reflected XSS through a brute-force attack on the PHP mt_rand function, leading to predictable file names.

The Impact of CVE-2021-39249

The vulnerability allows attackers to execute malicious scripts in the context of a user's session, potentially leading to unauthorized actions or data theft.

Technical Details of CVE-2021-39249

In-depth technical information about the vulnerability.

Vulnerability Description

The issue arises due to the predictability of file names of uploaded content, which can be exploited through a brute-force attack on the PHP mt_rand function.

Affected Systems and Versions

Product: Invision Community (IP.Board)
Versions affected: All versions prior to 4.6.5.1

Exploitation Mechanism

Attackers can exploit the vulnerability by manipulating file uploads to execute arbitrary scripts through reflected XSS.

Mitigation and Prevention

Steps to prevent and mitigate the CVE-2021-39249 vulnerability.

Immediate Steps to Take

Upgrade to version 4.6.5.1 or later to patch the vulnerability.
Exercise caution with file uploads and content from untrusted sources.
Regularly monitor for any suspicious activities or file uploads.

Long-Term Security Practices

Implement input validation mechanisms to prevent XSS attacks.
Conduct regular security audits and penetration testing to identify vulnerabilities.

Patching and Updates

Stay updated with security patches and software updates provided by Invision Community to address known vulnerabilities.