CVE-2024-37734

Executive Summary

CVE-2024-37734 is a privilege escalation vulnerability in OpenEMR version 7.0.2. A remote attacker can exploit this flaw by sending a crafted POST request with a malicious noteid parameter, leading to unauthorized privilege escalation. The vulnerability has a CVSS score of 0.0 (unscored) and an EPSS score of 0.0%, indicating low exploitation likelihood at this time. No official patch or GitHub advisory is available, and no public exploit code or Nuclei template has been released. The vulnerability is classified under CWE-269 (Improper Privilege Management) and aligns with MITRE ATT&CK tactic T1068 (Exploitation for Privilege Escalation).

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Unscored)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High
• Threat Level: High (based on impact, despite low EPSS)

Deep Dive & Mechanics

The vulnerability resides in the handling of the noteid parameter within a POST request. OpenEMR 7.0.2 fails to properly validate or sanitize this parameter, allowing an attacker to manipulate it to escalate privileges. The exact endpoint is not publicly documented, but the flaw likely exists in a function that processes patient notes or clinical notes, where the noteid is used to fetch or modify records. By crafting a POST request with a specially crafted noteid, an attacker can bypass authorization checks and gain elevated privileges, such as administrative access.

The root cause is improper privilege management (CWE-269). The application does not verify that the authenticated user has the right to access or modify the resource identified by noteid. This allows an attacker to escalate from a low-privileged user to a higher-privileged role, potentially compromising the entire OpenEMR instance.

Vulnerable vs. Patched Code

No patched version or code diff is available. The vulnerable code is in OpenEMR 7.0.2. The following is a hypothetical vulnerable code snippet:

// Vulnerable code in OpenEMR 7.0.2
$noteid = $_POST['noteid'];
$note = getNoteById($noteid); // No privilege check
if ($note) {
    // Process note
}

A patched version would include an authorization check:

// Patched code
$noteid = $_POST['noteid'];
$note = getNoteById($noteid);
if ($note && checkUserPrivilege($noteid)) {
    // Process note
} else {
    // Deny access
}

Exploitation & Lab Setup

Red Team

1. Setup: Deploy OpenEMR 7.0.2 in a lab environment (e.g., Docker).
2. Recon: Identify the vulnerable endpoint (e.g., /interface/notes/note.php).
3. Craft Payload: Create a POST request with a manipulated noteid parameter.

   POST /interface/notes/note.php HTTP/1.1
   Host: target
   Content-Type: application/x-www-form-urlencoded
   Cookie: PHPSESSID=attacker_session
   
   noteid=9999&action=edit
   

4. Execute: Send the request using curl or Burp Suite.

   curl -X POST http://target/interface/notes/note.php -d "noteid=9999&action=edit" -b "PHPSESSID=attacker_session"
   

5. Escalate: If successful, the attacker gains elevated privileges.

Blue Team

1. Monitor: Watch for anomalous POST requests to note-related endpoints with unusual noteid values.
2. Log Analysis: Check web server logs for requests with noteid parameters that are out of range or non-numeric.
3. Harden: Implement input validation and authorization checks on all noteid parameters.
4. Detect: Use the detection rules below.

Indicators of Compromise (IOCs)

• Network: POST requests to /interface/notes/note.php or similar endpoints with noteid parameter.
• Logs: Web server logs showing noteid values that are not valid note IDs (e.g., very high numbers, strings, or SQL-like patterns).
• System: Unauthorized privilege escalation events in application logs.
• File: Modified or accessed note records without proper authorization.

Detection Engineering

YARA Rule

rule CVE_2024_37734_OpenEMR_PrivEsc {
    meta:
        description = "Detects exploitation attempts of CVE-2024-37734 in OpenEMR"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-37734"
    strings:
        $s1 = "noteid="
        $s2 = "POST"
        $s3 = "/interface/notes/"
    condition:
        all of them
}

Sigma Rule

title: CVE-2024-37734 OpenEMR Privilege Escalation Attempt
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects POST requests with suspicious noteid parameter to OpenEMR
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'noteid='
        cs-uri-stem|contains: '/interface/notes/'
    condition: selection
falsepositives:
    - Legitimate note editing
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-37734 OpenEMR Privilege Escalation Attempt"; flow:to_server; content:"POST"; http_method; content:"/interface/notes/"; http_uri; content:"noteid="; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate: Disable the vulnerable endpoint or restrict access via web server configuration (e.g., .htaccess).
• Short-term: Implement input validation and authorization checks on the noteid parameter.
• Long-term: Upgrade to a patched version once available. Monitor OpenEMR security advisories.
• Workaround: Use a Web Application Firewall (WAF) to block suspicious POST requests with anomalous noteid values.

Valters IT
Securing Digital Frontiers