CVE-2024-10439

Executive Summary

CVE-2024-10439 is an Insecure Direct Object Reference (IDOR) vulnerability in Sunnet’s eHRD CTMS (Clinical Trial Management System). The flaw allows an unauthenticated remote attacker to manipulate a specific parameter in HTTP requests, enabling unauthorized access to arbitrary files uploaded by any user. With a CVSS score of 5.3 (Medium), the vulnerability primarily impacts confidentiality, as an attacker can read sensitive documents without authentication. No public exploit code or patch is currently available, and the EPSS score is 0.0%, indicating low exploitation activity in the wild. This report provides a deep technical analysis, detection rules, and mitigation strategies.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Base Score: 5.3 (Medium)
• Attack Vector: Network (AV:N) – exploitable remotely.
• Attack Complexity: Low (AC:L) – no special conditions required.
• Privileges Required: None (PR:N) – unauthenticated exploitation.
• User Interaction: None (UI:N) – no victim action needed.
• Scope: Unchanged (S:U) – impact confined to the vulnerable component.
• Confidentiality Impact: Low (C:L) – limited file access, but sensitive data may be exposed.
• Integrity Impact: None (I:N) – no file modification possible.
• Availability Impact: None (A:N) – no denial of service.

Threat Level: Medium. The vulnerability is easy to exploit but limited to read-only access. However, if the system stores PHI (Protected Health Information) or proprietary clinical trial data, the actual business impact could be high.

Deep Dive & Mechanics

The eHRD CTMS application exposes file upload functionality without proper authorization checks. The IDOR vulnerability stems from the application using a direct reference (e.g., a file ID or path parameter) to retrieve uploaded files without verifying that the requesting user owns or is permitted to access that file.

Root Cause: The server-side code likely performs a query like:

SELECT file_data FROM uploads WHERE file_id = $_GET['file_id'];

without joining against a user ownership table or validating a session token. An attacker can enumerate or brute-force file IDs to access any user’s uploaded documents.

Attack Flow:

1. An unauthenticated attacker sends a GET request to the vulnerable endpoint, e.g., /download.php?file_id=123.
2. The server returns the file content without checking authentication or authorization.
3. The attacker iterates through file IDs (e.g., 1, 2, 3…) to exfiltrate all uploaded files.

Potential Impact: Exposure of clinical trial data, patient records, internal reports, or credentials stored in uploaded documents.

Vulnerable vs. Patched Code

Since no patch is available, the following illustrates the vulnerable pattern and a hypothetical fix.

Vulnerable Code (PHP example):

<?php
$file_id = $_GET['file_id'];
$query = "SELECT file_path FROM uploads WHERE id = $file_id";
$result = mysqli_query($conn, $query);
$row = mysqli_fetch_assoc($result);
readfile($row['file_path']);
?>

Patched Code (Hypothetical):

<?php
session_start();
if (!isset($_SESSION['user_id'])) {
    die("Unauthorized");
}
$file_id = intval($_GET['file_id']);
$user_id = $_SESSION['user_id'];
$query = "SELECT file_path FROM uploads WHERE id = $file_id AND user_id = $user_id";
$result = mysqli_query($conn, $query);
if (mysqli_num_rows($result) == 0) {
    die("Access denied");
}
$row = mysqli_fetch_assoc($result);
readfile($row['file_path']);
?>

Exploitation & Lab Setup

Red Team (Offensive)

Lab Environment:

• Target: Sunnet eHRD CTMS (version unknown, but any instance with file upload functionality).
• Tools: Burp Suite, curl, or a simple Python script.

Exploitation Steps:

1. Identify the file download endpoint (e.g., /download.php?file_id=1).
2. Send a request without any authentication headers:

   curl -v "http://target.com/download.php?file_id=1"
   

3. If the file is returned, iterate through IDs:

   for i in {1..1000}; do curl -o "file_$i" "http://target.com/download.php?file_id=$i"; done
   

4. Analyze downloaded files for sensitive data.

No public exploit code is available; the above is a generic IDOR exploitation technique.

Blue Team (Defensive)

Detection & Prevention:

• Monitor for sequential or rapid requests to file download endpoints from a single IP.
• Implement Web Application Firewall (WAF) rules to block requests lacking session tokens.
• Enforce authentication and authorization on all file access endpoints.
• Use random, non-sequential file identifiers (e.g., UUIDs) to prevent enumeration.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Repeated GET requests to /download.php?file_id= or similar endpoints with sequential IDs.
  • Unauthenticated HTTP requests to file download URIs.
• File IOCs:
  • Unexpected presence of downloaded files in attacker-controlled directories.
• Log IOCs:
  • Web server logs showing 200 OK responses for file download requests without prior authentication.
  • High volume of requests to a single endpoint from a single IP in a short time.

Detection Engineering

YARA Rule

rule CVE_2024_10439_IDOR_Access {
    meta:
        description = "Detects attempts to exploit CVE-2024-10439 IDOR in Sunnet eHRD CTMS"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-10439"
    strings:
        $file_param = "file_id=" nocase
        $download_path = "/download.php" nocase
    condition:
        $file_param and $download_path
}

Sigma Rule

title: CVE-2024-10439 IDOR Exploitation Attempt
id: 8a9b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects unauthenticated sequential file download requests indicative of IDOR exploitation
author: Valters IT
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 'file_id='
        sc-status: 200
    condition: selection
falsepositives:
    - Legitimate file sharing with sequential IDs (rare)
level: high

Suricata Rule

alert http any any -> $HOME_NET any (
    msg:"CVE-2024-10439 IDOR Exploitation Attempt";
    flow:to_server,established;
    content:"GET"; http_method;
    content:"/download.php"; http_uri;
    content:"file_id="; http_uri;
    pcre:"/file_id=\d+/";
    classtype:attempted-recon;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate the system: If possible, restrict network access to the eHRD CTMS until a patch is applied.
2. Implement authentication: Enforce session-based or token-based authentication on all file download endpoints.
3. Apply access controls: Ensure users can only access files they own (e.g., via user_id join).
4. Use non-sequential IDs: Replace integer file IDs with UUIDs or hashed identifiers.

Long-Term Fix:

• Contact Sunnet for an official patch. Since the vendor status is UNKNOWN, consider migrating to a supported alternative.
• Conduct a full security audit of the application for similar IDOR flaws.

Workaround:

• Deploy a WAF rule to block requests to /download.php without a valid session cookie.
• Monitor logs for anomalous file access patterns.

Valters IT
Securing Digital Frontiers