Security researchers have recently unearthed a critical vulnerability, assigned the CVE identifier CVE-2023-27179, in GDidees CMS v3.9.1 and lower versions. The vulnerability allows malicious attackers to download arbitrary files from the affected systems by exploiting a weakly protected filename parameter at /_admin/imgdownload.php. In this post, we will delve deep into this vulnerability and explore its potential impact, the code snippet that demonstrates the issue in GDidees CMS, and possible remediation steps.
Vulnerability Overview
The arbitrary file download vulnerability stems from the improper handling of user-supplied input in the filename parameter in /_admin/imgdownload.php. In essence, an attacker can supply a malicious payload via this parameter to force the application to download arbitrary files from the server. This vulnerability poses a serious risk, as cybercriminals can potentially gain access to sensitive files, including configuration files, databases, or even private files belonging to users.
An inspection of the vulnerable code snippet in /_admin/imgdownload.php reveals the following code
<?php
$filename = $_GET['filename'];
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename='.basename($filename));
header('Content-Transfer-Encoding: binary');
header('Expires: ');
header('Cache-Control: must-revalidate');
header('Pragma: public');
header('Content-Length: ' . filesize($filename));
ob_clean();
flush();
readfile($filename);
exit;
?>
As evident from the code snippet above, the filename parameter is directly passed to the readfile function, without proper verification. This allows an attacker to exploit this vulnerability by providing a malicious payload through the parameter.
An attacker can exploit this vulnerability using a crafted URL, as shown below
http://example.com/_admin/imgdownload.php?filename=../../../../../../etc/passwd
By replacing "example.com" with the target website URL and sending this malicious URL to the victim, the attacker can force the application to download arbitrary files like /etc/passwd, which contains crucial information about the system's accounts.
References
- CVE-2023-27179 Mitre Details
- Exploit Database
- National Vulnerability Database
- GDidees CMS Official Webpage
Mitigation Steps
To protect against this arbitrary file download vulnerability, website administrators should implement the following recommendations:
1. Update GDidees CMS to the latest version, as newer versions may include patches addressing this vulnerability.
Limit user permissions and restrict access to sensitive files.
4. Employ a Web Application Firewall (WAF) to block malicious requests that aim to exploit vulnerabilities.
Closing Thoughts
The discovery of CVE-2023-27179 highlights the importance of ensuring that web applications are secure and receive regular updates. Cybersecurity is a continuous process of identifying potential security gaps and making improvements to protect valuable data and infrastructure from cyber threats. By staying informed about vulnerabilities like this and taking the necessary steps to patch and protect systems, individuals and organizations can help reduce the risk of successful attacks.
Timeline
Published on: 04/11/2023 12:15:00 UTC
Last modified on: 04/17/2023 17:15:00 UTC