CVE-2022-39022 - U-Office Force Download Function Path Traversal Vulnerability: Exploit Details, Remediation, and Original References

CVE-2022-39022 is a significant vulnerability discovered in the U-Office Force Download function, which presents a path traversal risk. With the potential to impact multiple organizations and users, it's crucial to understand the specifics of this security concern, how it can be exploited, and what to do to protect yourself and your systems.

CVE-2022-39022 Overview

The U-Office Force Download function has been identified to have a path traversal vulnerability. This flaw enables attackers, even those with just general user privilege, to exploit the system and download arbitrary files. Notably, this vulnerability can lead to the exposure of sensitive information, unauthorized access to system files, and further exploitation of an affected organization's infrastructure.

The path traversal vulnerability can be demonstrated using the following example code snippet

<?php
$file = $_GET['file'];
$force_download = $_GET['force_download'];

if ($force_download) {
    $file_path = 'downloads/' . $file;

    // Vulnerable to path traversal
    $real_file_path = realpath($file_path);

    if (file_exists($real_file_path)) {
        header("Content-Type: application/octet-stream");
        header("Content-Disposition: attachment; filename=" . urlencode($file));
        header("Content-Transfer-Encoding: binary");

        readfile($real_file_path);
    } else {
        echo "File not found.";
    }
}
?>

In this code snippet, the $file variable is obtained directly from the user input ($_GET['file']), and the application doesn't validate or sanitize it. As a result, an attacker can manipulate the file path by using .. to traverse the directory structure and download any system file.

Exploit Details

To exploit this vulnerability, an attacker with general user privileges would use a carefully crafted HTTP request, with the file parameter containing the path traversal payload:

GET /vulnerable_page.php?file=../../../../../etc/passwd&force_download=true

By manipulating the input, the attacker can access sensitive system files (e.g., /etc/passwd on Linux systems), exfiltrate data, and potentially obtain confidential information related to the organization's infrastructure. This could lead to further attacks on the affected system or even other systems within the network.

Original References

This vulnerability was documented and assigned the CVE identifier CVE-2022-39022, which can be explored in greater detail on the following sites:

1. The CVE List: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-39022
2. The National Vulnerability Database (NVD): https://nvd.nist.gov/vuln/detail/CVE-2022-39022

Remediation

To address the issue and protect your system from exploitation, it's necessary to implement measures that sanitize and validate user inputs, for example:

<?php
$file = basename($_GET['file']);
$force_download = $_GET['force_download'];

if ($force_download) {
    $file_path = 'downloads/' . $file;

    // Resolves path traversal issue
    $real_file_path = realpath($file_path);

    if (file_exists($real_file_path)) {
        // ... Implement the code to force a download ...
    } else {
        echo "File not found.";
    }
}
?>

By using the basename() function, the input is sanitized and the path traversal attempt is neutralized. Developers are also encouraged to adopt best practices for input validation and ensure that their code and dependencies are up-to-date with the latest security patches.

Stay informed and protect your infrastructure from potential threats by remaining diligent in monitoring for new vulnerabilities and applying the necessary updates and fixes.

Timeline

Published on: 10/31/2022 07:15:00 UTC