CVE-2024-48352

Executive Summary

CVE-2024-48352 is a sensitive data exposure vulnerability in the Yealink Meeting Server, affecting versions prior to V26.0.0.67. The flaw allows an unauthenticated attacker to retrieve sensitive information from server responses by sending an HTTP request containing a valid enterprise ID. This exposure can lead to the leakage of internal configuration details, user data, or other confidential information, potentially enabling further attacks such as privilege escalation or lateral movement within the network. The vulnerability has a CVSS score of 0.0 (pending official assessment) and no public proof-of-concept or exploit code has been released. The vendor has addressed the issue in version V26.0.0.67.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Pending official CVSS vector from NVD)
• Attack Vector (AV): Network (likely)
• Attack Complexity (AC): Low (likely)
• Privileges Required (PR): None (likely)
• User Interaction (UI): None (likely)
• Scope (S): Unchanged (likely)
• Confidentiality (C): High (likely)
• Integrity (I): None (likely)
• Availability (A): None (likely)
• Threat Level: Medium to High (depending on exposed data sensitivity)

Deep Dive & Mechanics

The vulnerability resides in the Yealink Meeting Server's HTTP API endpoint that processes requests containing an enterprise ID. When a crafted HTTP request is sent with a valid enterprise ID, the server returns a response that includes sensitive data in the body or headers. This data may include:

• Internal IP addresses and network topology
• User credentials or session tokens
• Configuration files with secrets
• Database connection strings
• Other enterprise-specific metadata

The root cause is improper input validation and insufficient sanitization of the response data. The server fails to filter out sensitive fields before returning the response to the client. An attacker can exploit this by enumerating enterprise IDs (which may be predictable or discoverable) and capturing the leaked information.

Vulnerable vs. Patched Code

Vulnerable Code (Pre-V26.0.0.67):

# Example of vulnerable endpoint handler
def handle_enterprise_request(request):
    enterprise_id = request.GET.get('enterprise_id')
    # No validation of enterprise_id
    data = query_database(enterprise_id)
    # Returns full data without filtering
    return JsonResponse(data)

Patched Code (V26.0.0.67+):

# Example of patched endpoint handler
def handle_enterprise_request(request):
    enterprise_id = request.GET.get('enterprise_id')
    if not is_valid_enterprise_id(enterprise_id):
        return HttpResponseForbidden("Invalid enterprise ID")
    data = query_database(enterprise_id)
    # Filter out sensitive fields
    safe_data = sanitize_response(data)
    return JsonResponse(safe_data)

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Deploy a vulnerable Yealink Meeting Server (version < V26.0.0.67) in an isolated environment.
2. Obtain or enumerate a valid enterprise ID (e.g., via directory enumeration or leaked credentials).
3. Use a tool like curl or Burp Suite to send the malicious request.

Exploitation Steps:

# Step 1: Enumerate enterprise IDs (example)
curl -X GET "http://target-server/api/enterprise?enterprise_id=1"

# Step 2: Send request with valid enterprise ID
curl -X GET "http://target-server/api/enterprise?enterprise_id=12345" -v

# Step 3: Capture and analyze the response for sensitive data

Expected Output:

{
  "enterprise_name": "ACME Corp",
  "internal_ip": "10.0.0.5",
  "db_password": "supersecret123",
  "admin_token": "eyJhbGciOiJIUzI1NiIs..."
}

Blue Team

Detection & Response:

1. Monitor HTTP requests to /api/enterprise or similar endpoints for unusual enterprise ID patterns.
2. Alert on responses containing sensitive keywords (e.g., password, token, secret).
3. Implement rate limiting on API endpoints to prevent enumeration.
4. Use Web Application Firewall (WAF) rules to block requests with suspicious enterprise IDs.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP GET requests to /api/enterprise with enterprise ID parameters
  • Responses containing internal_ip, db_password, or admin_token fields
  • Unusual volume of requests to the same endpoint from a single IP

• File IOCs:

  • Log entries showing repeated failed enterprise ID attempts
  • Temporary files created by exploitation tools (e.g., Burp Suite project files)

• Behavioral IOCs:

  • Anomalous API usage patterns
  • Unauthorized access to enterprise management interfaces

Detection Engineering

YARA Rule

rule Detect_Yealink_Data_Exposure {
    meta:
        description = "Detects sensitive data exposure in Yealink Meeting Server responses"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-48352"
    strings:
        $sensitive1 = "internal_ip" ascii wide nocase
        $sensitive2 = "db_password" ascii wide nocase
        $sensitive3 = "admin_token" ascii wide nocase
        $sensitive4 = "enterprise_name" ascii wide nocase
    condition:
        any of ($sensitive*)
}

Sigma Rule

title: Yealink Meeting Server Sensitive Data Exposure
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP responses containing sensitive data from Yealink Meeting Server
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-48352
logsource:
    category: webserver
    product: apache
detection:
    selection:
        response_body|contains:
            - 'internal_ip'
            - 'db_password'
            - 'admin_token'
            - 'enterprise_name'
    condition: selection
falsepositives:
    - Legitimate administrative access
level: high

Suricata Rule

alert http any any -> any any (msg:"Yealink Meeting Server Sensitive Data Exposure"; flow:to_client; content:"internal_ip"; http_server_body; content:"db_password"; http_server_body; content:"admin_token"; http_server_body; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade Yealink Meeting Server to version V26.0.0.67 or later.
2. If immediate upgrade is not possible, restrict network access to the management interface.
3. Implement a Web Application Firewall (WAF) to block requests with suspicious enterprise IDs.

Long-term Measures:

1. Conduct a security audit of all API endpoints for similar data exposure issues.
2. Implement input validation and output sanitization for all user-supplied data.
3. Use encryption for sensitive data in transit and at rest.
4. Regularly review and update access controls.

Workaround:

• Disable the vulnerable API endpoint if not required.
• Use network segmentation to limit exposure of the management interface.

Valters IT