CVE-2024-56279

Executive Summary

CVE-2024-56279 is a Server-Side Request Forgery (SSRF) vulnerability in the Compact WP Audio Player WordPress plugin, developed by mra13. The flaw affects all versions up to and including 1.9.14. An unauthenticated attacker can exploit this vulnerability to make the server send crafted HTTP requests to internal or external resources, potentially leading to information disclosure, internal network scanning, or further lateral movement. The CVSS v3.1 base score is 6.4 (Medium), with a vector of AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N. No public proof-of-concept (PoC) or exploit code has been released, and no official patch is available from the vendor. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains due to the unpatched state.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin ecosystem. The plugin is distributed via the official WordPress plugin repository and can be installed directly from the WordPress admin dashboard. Since no patch is available, users must consider removing or disabling the plugin to mitigate risk. The plugin’s supply chain is not directly affected, but the lack of vendor response increases the risk of supply chain compromise if the plugin is used in production environments.

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: 6.4 (Medium)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – The vulnerability does not affect other components.
• Confidentiality Impact: Low (C:L) – Limited information disclosure possible.
• Integrity Impact: Low (I:L) – Limited ability to modify data.
• Availability Impact: None (A:N) – No denial-of-service impact.

Threat Level: Medium. While the CVSS score is moderate, the SSRF nature can be leveraged for internal reconnaissance and potential pivot attacks, especially in cloud environments with metadata endpoints.

Deep Dive & Mechanics

The vulnerability exists in the compact-wp-audio-player plugin’s audio file fetching functionality. The plugin likely accepts a URL parameter to fetch audio files from external sources. Due to insufficient validation of the URL, an attacker can supply a malicious URL pointing to internal resources (e.g., http://169.254.169.254/latest/meta-data/ for AWS metadata) or other internal services. The server then makes an HTTP request to that URL, returning the response to the attacker.

Root Cause: The plugin does not sanitize or restrict the URL scheme, host, or port, allowing arbitrary HTTP/HTTPS requests from the server.

Attack Flow:

1. Attacker identifies a WordPress site using the vulnerable plugin.
2. Attacker crafts a request to the plugin’s audio player endpoint with a malicious URL.
3. The server fetches the URL and returns the content (or error messages) to the attacker.
4. Attacker uses this to probe internal services, read cloud metadata, or perform port scanning.

Vulnerable vs. Patched Code

Since no official patch exists, the vulnerable code is presumed to be in the plugin’s main PHP file (e.g., compact-wp-audio-player.php). A typical vulnerable pattern might look like:

// Vulnerable code (hypothetical)
$audio_url = $_GET['audio_url'];
$response = wp_remote_get($audio_url);
echo wp_remote_retrieve_body($response);

A patched version would include URL validation:

// Patched code (hypothetical)
$audio_url = $_GET['audio_url'];
if (filter_var($audio_url, FILTER_VALIDATE_URL) && 
    preg_match('/^https?:\/\/([a-zA-Z0-9\-]+\.)+[a-zA-Z]{2,}/', $audio_url)) {
    $response = wp_remote_get($audio_url);
    echo wp_remote_retrieve_body($response);
} else {
    echo "Invalid URL";
}

Note: The above is illustrative. Actual patching requires vendor action.

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress instance with Compact WP Audio Player <= 1.9.14 installed and activated.
• A listener (e.g., netcat) to capture outbound requests.

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /wp-content/plugins/compact-wp-audio-player/audio-player.php?audio_url=).
2. Send a crafted request to fetch internal resources:

   curl "http://target.com/wp-content/plugins/compact-wp-audio-player/audio-player.php?audio_url=http://169.254.169.254/latest/meta-data/"
   

3. Observe the response containing cloud metadata.
4. For internal port scanning, use:

   curl "http://target.com/wp-content/plugins/compact-wp-audio-player/audio-player.php?audio_url=http://192.168.1.1:80"
   

Note: No public exploit code is available; this is a conceptual demonstration.

Blue Team

Detection & Response:

• Monitor outbound HTTP requests from the web server to unusual IPs or internal ranges.
• Look for requests to cloud metadata IPs (169.254.169.254) or private IPs (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16).
• Use web application firewall (WAF) rules to block requests containing internal IPs in URL parameters.
• Disable or remove the plugin until a patch is available.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound HTTP requests to 169.254.169.254 or other cloud metadata endpoints.
  • Requests to private IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) from the web server.
  • Unusual User-Agent strings in server logs (e.g., curl/7.x).
• File IOCs:
  • Modified plugin files (e.g., compact-wp-audio-player.php) with suspicious URL parameters.
• Log IOCs:
  • Repeated GET requests to the plugin’s audio player endpoint with varying audio_url parameters.

Detection Engineering

YARA Rule

rule CVE_2024_56279_SSRF_CompactWP_AudioPlayer {
    meta:
        description = "Detects SSRF exploitation attempts against Compact WP Audio Player"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-56279"
    strings:
        $url_param = "audio_url=" nocase
        $internal_ip = /(10\.\d{1,3}\.\d{1,3}\.\d{1,3}|172\.(1[6-9]|2\d|3[01])\.\d{1,3}\.\d{1,3}|192\.168\.\d{1,3}\.\d{1,3}|169\.254\.\d{1,3}\.\d{1,3})/
        $cloud_metadata = "169.254.169.254" nocase
    condition:
        $url_param and ($internal_ip or $cloud_metadata)
}

Sigma Rule

title: CVE-2024-56279 SSRF Exploitation via Compact WP Audio Player
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects SSRF attempts targeting internal IPs via the Compact WP Audio Player plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-uri-query|contains: "audio_url="
        cs-uri-query|contains:
            - "169.254.169.254"
            - "10."
            - "172.16."
            - "172.17."
            - "172.18."
            - "172.19."
            - "172.20."
            - "172.21."
            - "172.22."
            - "172.23."
            - "172.24."
            - "172.25."
            - "172.26."
            - "172.27."
            - "172.28."
            - "172.29."
            - "172.30."
            - "172.31."
            - "192.168."
    condition: selection
falsepositives:
    - Legitimate use of internal audio sources (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2024-56279 SSRF Exploitation via Compact WP Audio Player";
    flow:to_server,established;
    content:"audio_url="; http_uri;
    pcre:"/(169\.254\.169\.254|10\.\d{1,3}\.\d{1,3}\.\d{1,3}|172\.(1[6-9]|2\d|3[01])\.\d{1,3}\.\d{1,3}|192\.168\.\d{1,3}\.\d{1,3})/";
    sid:1000001;
    rev:1;
    reference:cve,2024-56279;
    priority:2;
)

Remediation & Mitigation

Immediate Actions:

1. Disable or remove the Compact WP Audio Player plugin from all WordPress installations.
2. Implement WAF rules to block requests containing internal IP addresses in URL parameters.
3. Monitor logs for SSRF patterns as described in IOCs.

Long-term Fix:

• Await an official patch from the vendor. If none is forthcoming, consider migrating to an alternative audio player plugin with active maintenance.
• Apply network segmentation to limit outbound HTTP requests from web servers to only necessary external services.

Valters IT – Securing digital frontiers, one CVE at a time.