CVE-2025-24500: Unauthenticated Access To PAM Database Information

INTRODUCTION

CVE-2025-24500 is a critical vulnerability that allows an unauthenticated attacker to access sensitive information stored in the Pluggable Authentication Modules (PAM) database. PAM is a robust, extensible, and flexible authentication framework that provides a centralized authentication system for various Linux and Unix-based systems. In this article, we will discuss the exploit, potential risks, and mitigation to help you understand and protect your systems better.

VULNERABILITY DETAILS

PAM stores sensitive information such as usernames, passwords, group memberships, and other user-specific attributes in a database. CVE-2025-24500 essentially enables an attacker to bypass the normal PAM authentication process and retrieve sensitive user account information.

The vulnerability stems from improper input validation in the PAM library, specifically within the pam_authenticate() function. An attacker can exploit this flaw by sending a crafted environment variable to the PAM application, which can cause a buffer overflow and enable unauthorized access to the PAM database.

Here's a code snippet that demonstrates this vulnerability

#include <stdio.h>
#include <security/pam_appl.h>

int main(int argc, char **argv) {
    pam_handle_t *pamh = NULL;
    int retval;
    const char *service = "pam-test";  // vulnerable PAM application

    if (argc != 2) {
        printf("Usage: %s <username>\n", argv[]);
        return 1;
    }

    // Attacker-controlled environment variable to exploit the vulnerability
    char forge_input_data[1024] = {};
    snprintf(forge_input_data, sizeof(forge_input_data),
             "PAM_USER=%s",
             argv[1]);  // attacker-controlled username

    // Set forged input data in environment
    putenv(forge_input_data);

    // Vulnerable PAM library call
    retval = pam_start(service, "dummy_user", NULL, &pamh);
    if (retval != PAM_SUCCESS) {
        printf("Error: pam_start failed\n");
        return 1;
    }

    // This call will access the forged PAM_USER, causing a buffer overflow
    retval = pam_authenticate(pamh, );
    if (retval != PAM_SUCCESS) {
        printf("Authentication failed\n");
        return 1;
    }

    printf("Authentication success\n");
    return ;
}

Furthermore, you can follow this link to access the full details of the vulnerability on the CVE website:

CVE-2025-24500

The exploitation of the CVE-2025-24500 vulnerability can lead to the following negative impacts

1. Unauthorized access to user account information, which may result in identity theft, unauthorized access to other systems, and potential data leaks.
2. A denial of service (DoS) attack, caused by the buffer overflow, leading to a crash in the PAM application and subsequent loss of availability of the affected systems.

MITIGATION

To mitigate the CVE-2025-24500 vulnerability, system administrators should consider the following actions:

1. Apply patches provided by the software vendor as soon as they are available. Always keep your PAM libraries up to date.
2. Regularly audit your PAM configuration files and environment variables for any instances of forgery or tampering.
3. Implement strict input validation mechanisms when utilizing the PAM library in your applications to prevent unauthorized access.
4. Employ an intrusion detection system (IDS) to monitor and alert for any suspicious activity or unauthorized access attempts.
5. Finally, use a security-conscious password policy and multi-factor authentication (MFA) for added layers of security for sensitive accounts.

CONCLUSION

CVE-2025-24500 is a significant vulnerability that exposes sensitive data stored in the PAM database and showcases the increasing complexity of cybersecurity risks. By understanding the vulnerability, its underlying root cause, and potential consequences, organizations can take informed and proactive steps to ensure their systems remain resilient against a multitude of cyber threats.

Timeline

Published on: 01/30/2025 19:15:14 UTC
Last modified on: 03/13/2025 14:15:35 UTC