CVE-2023-6991: Critical SSRF Vulnerability in JSM’s file_get_contents() Shortcode WordPress Plugin

Overview

CVE-2023-6991 is a significant cybersecurity vulnerability that affects the JSM file_get_contents() Shortcode WordPress plugin. This flaw could enable attackers, especially those with contributor role and above, to perform Server Side Request Forgery (SSRF) attacks. Such an attack allows an attacker to cause the server to make requests to internal resources within the network, leading to potential system compromise or data leakage. Given the extensive use of WordPress, this vulnerability is a considerable cybersecurity concern that needs immediate addressing.

Vulnerability Summary

CVE ID: CVE-2023-6991
Severity: Critical (8.8 CVSS Severity Score)
Attack Vector: Network
Privileges Required: Low (Contributor role and above)
User Interaction: Required
Impact: System compromise and potential data leakage

Affected Products

Product | Affected Versions

JSM’s file_get_contents() Shortcode WordPress Plugin | Before 2.7.1

How the Exploit Works

The vulnerability lies in the lack of validation of one of its shortcode’s parameters by the JSM file_get_contents() Shortcode WordPress plugin. This omission means that when a request is made, an attacker with contributor role and above can manipulate this parameter to initiate SSRF attacks. By exploiting this vulnerability, an attacker can make the WordPress server send a request to an arbitrary address, potentially leading to unauthorized access to sensitive information or system compromise.

Conceptual Example Code

A hypothetical example of how this vulnerability might be exploited is an HTTP request that contains a malicious payload. The payload might be a URL that the server would then request, potentially exposing sensitive data or executing malicious code. Here is a conceptual example:

POST /vulnerable/shortcode HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "shortcode_parameter": "http://malicious.example.com" }

In this example, an attacker with a contributor role sends a POST request to the vulnerable shortcode endpoint, with the shortcode_parameter set to a malicious URL. The server, due to the vulnerability, does not validate this parameter and makes a request to the malicious URL, potentially leading to SSRF attack.

Mitigation Measures

The most effective way to address this vulnerability is to apply the vendor patch. JSM has released a patch in version 2.7.1 of the plugin, so users should update as soon as possible. If immediate patching is not possible, users can try to mitigate the risk temporarily by using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to detect and block any SSRF attempts. However, these measures are not foolproof and should not replace patching.