CVE-2025-4596

Executive Summary

CVE-2025-4596 is an Insecure Direct Object Reference (IDOR) vulnerability in the Asseco ADMX system, a platform used for processing medical records. The flaw allows authenticated users to access medical files belonging to other users by manipulating GET arguments containing document IDs. This vulnerability poses a significant risk to patient data confidentiality and privacy, as it enables unauthorized access to sensitive medical records. The issue has been addressed in ADMX version 6.09.01.62.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, indicating that a full vector has not been officially assigned. However, based on the vulnerability description, a reasonable assessment would be:

• Attack Vector (AV): Network (N) – The vulnerability is exploitable over the network.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): Low (L) – An attacker needs a valid user account.
• User Interaction (UI): None (N) – No user interaction is required.
• Scope (S): Unchanged (U) – The vulnerable component and the impacted component are the same.
• Confidentiality (C): High (H) – Complete disclosure of medical records.
• Integrity (I): None (N) – No data modification is possible.
• Availability (A): None (N) – No impact on availability.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N Estimated Base Score: 6.5 (Medium)

Threat Level: High – The vulnerability allows direct access to sensitive medical data, which is protected by regulations like HIPAA and GDPR.

Deep Dive & Mechanics

The vulnerability is a classic Insecure Direct Object Reference (IDOR), classified under CWE-639. The ADMX system uses GET parameters to pass document IDs when users request medical files. The application fails to verify that the authenticated user has the proper authorization to access the document associated with the provided ID.

Mechanics:

1. A legitimate user logs into the ADMX system.
2. The user accesses a medical record, which generates a URL like: https://admx.example.com/viewDocument?docId=12345.
3. An attacker, who is also an authenticated user, can modify the docId parameter to another value (e.g., docId=12346).
4. The server processes the request without checking if the attacker is authorized to view document 12346.
5. The attacker receives the medical file belonging to another patient.

This is a server-side authorization failure. The application relies on the client-provided ID without performing a server-side access control check.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

# Vulnerable endpoint
@app.route('/viewDocument')
def view_document():
    doc_id = request.args.get('docId')
    # Directly fetches and returns the document without authorization check
    document = get_document_from_db(doc_id)
    return document

Patched Code (Conceptual):

# Patched endpoint
@app.route('/viewDocument')
def view_document():
    doc_id = request.args.get('docId')
    user_id = get_current_user_id()
    # Authorization check: verify user has access to the document
    if not user_has_access_to_document(user_id, doc_id):
        return "Unauthorized", 403
    document = get_document_from_db(doc_id)
    return document

The patched version introduces a server-side authorization check (user_has_access_to_document) that verifies the current user's relationship to the requested document before returning it.

Exploitation & Lab Setup

Red Team (Exploitation)

Lab Setup:

1. Deploy a vulnerable instance of Asseco ADMX (version < 6.09.01.62) in an isolated environment.
2. Create two user accounts: user1 and user2.
3. Log in as user1 and access a medical record, noting the docId value in the URL (e.g., docId=100).
4. Log in as user2 and attempt to access the same document by modifying the URL.

Exploitation Steps:

1. Authenticate to the ADMX system with valid credentials.
2. Intercept a legitimate document request using a proxy like Burp Suite.
3. Modify the docId parameter in the GET request to a different value.
4. Send the modified request.
5. If the response contains the medical file, the vulnerability is confirmed.

Example Request:

GET /viewDocument?docId=100 HTTP/1.1
Host: admx.example.com
Cookie: session=valid_user_session

Modified Request:

GET /viewDocument?docId=101 HTTP/1.1
Host: admx.example.com
Cookie: session=valid_user_session

Blue Team (Detection & Defense)

Detection:

• Monitor for multiple document access requests from a single user within a short time frame.
• Log and alert on failed authorization attempts (403 responses) for document access.
• Implement rate limiting on document access endpoints.

Defense:

• Apply the vendor patch by upgrading to ADMX version 6.09.01.62.
• Implement server-side authorization checks for all document access requests.
• Use indirect object references (e.g., random tokens) instead of sequential IDs.
• Conduct regular security audits and penetration testing.

Indicators of Compromise (IOCs)

• Network: Unusual patterns of GET requests to /viewDocument or similar endpoints with varying docId parameters from a single user.
• Logs: Multiple 403 Forbidden responses for document access, followed by successful access to documents not normally associated with the user.
• System: Unauthorized access to patient records in audit logs.

Detection Engineering

YARA Rule

rule Detect_ADMX_IDOR_Exploitation {
    meta:
        description = "Detects exploitation attempts of CVE-2025-4596 in Asseco ADMX logs"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-4596"
    strings:
        $s1 = "viewDocument" nocase
        $s2 = "docId=" nocase
        $s3 = "HTTP/1.1\" 200" nocase
    condition:
        all of ($s1, $s2, $s3)
}

Sigma Rule

title: Asseco ADMX IDOR Exploitation Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential exploitation of CVE-2025-4596 by monitoring for multiple document access requests with varying docId parameters.
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: "viewDocument?docId="
    condition: selection
falsepositives:
    - Legitimate users accessing multiple documents
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-4596 - Asseco ADMX IDOR Exploitation Attempt";
    flow:to_server,established;
    content:"GET"; http_method;
    content:"/viewDocument"; http_uri;
    content:"docId="; http_uri;
    classtype:attempted-recon;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Patch: Upgrade the Asseco ADMX system to version 6.09.01.62 or later.
2. Workaround: If patching is not immediately possible, implement a Web Application Firewall (WAF) rule to block requests with suspicious docId patterns or enforce strict session-based access controls at the application layer.

Long-Term Measures:

• Implement robust server-side authorization checks for all sensitive operations.
• Use indirect object references (e.g., random, non-sequential tokens) for document IDs.
• Conduct regular security assessments and code reviews.
• Monitor logs for anomalous access patterns.

Valters IT