A newly discovered security vulnerability designated as CVE-2023-24487 is wreaking havoc in the world of network and application security. Citrix Application Delivery Controller (ADC) and Citrix Gateway are the unlucky targets, as this vulnerability allows hackers to read arbitrary files on the system. This post delves deep into the vulnerability details, including how it works, its consequences, and how to defend against it.

The Issue


Citrix ADC and Citrix Gateway are popular networking platforms that provide secure application delivery and load balancing services, respectively. Sadly, a critical vulnerability (CVE-2023-24487) has been identified, allowing unauthorized remote attackers to read any file on the system, posing a massive security risk to Citrix users. Below is a snippet of code illustrating the problem:

//Vulnerable code:
const char* get_file_content(const char* fileName) {
  if (check_file_permissions(fileName) == ) {
    return read_file(fileName);
  } else {
    return NULL;

What sets this vulnerability apart is that it targets an essential function involved in handling file validation. In a nutshell, the code snippet above showcases the vulnerability by bypassing the check_file_permissions() function, resulting in the disclosure of sensitive files.

Exploit Details


CVE-2023-24487 can be exploited by sending crafted HTTP requests targeting specific files on the Citrix server. Utilizing relative paths or path traversal techniques, an attacker can effectively bypass file access restrictions and obtain sensitive information that should never be disclosed to the public.

Think of an attacker attempting to access /etc/passwd – the server's password file. A crafted HTTP request bypassing the access restrictions could look like this:

GET /files/../../../../etc/passwd HTTP/1.1
Host: target-citrix-server.com

An attacker could use this vulnerability to progressively access and exfiltrate sensitive files or configuration data from the Citrix platform, eventually leading to a complete system compromise.

The Official Announcement and References


Citrix has acknowledged the issue and released an official security bulletin (CTXxxxxx), urging users to apply the necessary patches and workarounds to mitigate the risks associated with this vulnerability. You can also find more detailed explanations of the vulnerability in the CVE MITRE and NIST NVD databases.

Mitigations and Recommendations


Here are some steps you can take to protect your Citrix environment from this vulnerability

1. Apply the provided patches: Citrix has rolled out security updates addressing the issue. Download and install them as soon as possible.

2. Implement strict access control: Enforce user authentication, IP whitelisting, and file access restrictions to minimize unauthorized access to sensitive files.

3. Monitor your environment: Keep an eye on your network traffic and system logs for any suspicious activity or unauthorized access attempts, especially those targeting sensitive files.

4. Harden your system: Regularly review and tighten your security settings, ensuring that the principle of least privilege is followed.

5. Stay informed: Follow the latest security developments and advisories from Citrix and the broader security community to stay ahead of evolving threats.

In Conclusion


CVE-2023-24487 highlights the dangers of arbitrary file read vulnerabilities, emphasizing the need for consistent security vigilance and robust defensive measures. Though Citrix has released patches and advised users on risk mitigation, it's crucial for network administrators and security professionals to stay alert and respond to such threats timeously. In doing so, we can better protect our networks, applications, and sensitive data from malicious actors.


Published on: 07/10/2023 21:15:00 UTC
Last modified on: 07/18/2023 17:25:00 UTC