CVE-2024-5579

Executive Summary

CVE-2024-5579 is a critical deserialization vulnerability in Allegra’s renderFieldMatch method, allowing authenticated remote attackers to execute arbitrary code in the context of the LOCAL SERVICE account. The flaw stems from improper validation of user-supplied data, leading to deserialization of untrusted objects. With a CVSS score of 7.2, this vulnerability poses a high risk to confidentiality, integrity, and availability. No public proof-of-concept (PoC) or exploit code is currently available, and the vendor has not released a patch. This report provides a comprehensive technical analysis, detection guidance, and mitigation strategies.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• Base Score: 7.2 (High)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (Authentication required)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

The threat level is High due to the low complexity, network-based attack vector, and full impact on system security. Although authentication is required, an attacker with low privileges can achieve remote code execution.

Deep Dive & Mechanics

The vulnerability resides in the renderFieldMatch method of Allegra, a project management application. The method deserializes user-supplied data without proper validation, allowing an attacker to inject malicious serialized objects. When deserialized, these objects can trigger arbitrary code execution in the context of the LOCAL SERVICE account, which has elevated privileges on the system.

Root Cause:

• The application uses Java deserialization (likely ObjectInputStream) without a whitelist or blacklist filter.
• User input is passed directly to the deserialization routine without sanitization.

Attack Flow:

1. Attacker authenticates to Allegra (low-privileged account).
2. Attacker crafts a malicious serialized object (e.g., using ysoserial with a gadget chain like CommonsCollections).
3. Attacker sends the payload to the renderFieldMatch endpoint.
4. The application deserializes the payload, triggering the gadget chain.
5. Arbitrary code executes in the LOCAL SERVICE context.

Impact:

• Full system compromise (data theft, lateral movement, ransomware deployment).
• Persistence via service account manipulation.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code pattern is described generically.

Vulnerable Code (Java-like pseudocode):

public void renderFieldMatch(HttpServletRequest request) {
    String data = request.getParameter("fieldData");
    ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(data.getBytes()));
    Object obj = ois.readObject(); // No validation
    // Process obj...
}

Patched Code (Recommended):

public void renderFieldMatch(HttpServletRequest request) {
    String data = request.getParameter("fieldData");
    // Validate input format (e.g., JSON only)
    if (!isValidJSON(data)) {
        throw new SecurityException("Invalid input");
    }
    // Use safe deserialization with whitelist
    Object obj = safeDeserialize(data, allowedClasses);
    // Process obj...
}

Key Differences:

• Input validation before deserialization.
• Use of a whitelist of allowed classes.
• Avoidance of ObjectInputStream directly.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• Allegra instance with a valid low-privileged account.
• Network access to the Allegra server.

Steps:

1. Reconnaissance: Identify the renderFieldMatch endpoint (e.g., /allegra/renderFieldMatch).
2. Craft Payload: Use ysoserial to generate a malicious serialized object:

   java -jar ysoserial.jar CommonsCollections5 'calc.exe' > payload.bin
   

3. Send Payload:

   curl -X POST -d "fieldData=$(cat payload.bin)" -u "user:pass" http://target/allegra/renderFieldMatch
   

4. Execute: The payload executes calc.exe (or a reverse shell) in the LOCAL SERVICE context.

Note: No public exploit code is available; this is a hypothetical simulation.

Blue Team (Defense & Detection)

Detection Steps:

• Monitor for unusual deserialization activity (e.g., large binary POST data to renderFieldMatch).
• Use network segmentation to limit access to Allegra.
• Deploy Web Application Firewall (WAF) rules to block serialized Java objects.

Honeypot:

• Set up a decoy Allegra endpoint logging all deserialization attempts.

Indicators of Compromise (IOCs)

• Network IOCs:

  • POST requests to /allegra/renderFieldMatch with binary payloads.
  • Unusual outbound connections from the LOCAL SERVICE account (e.g., to attacker C2).

• File IOCs:

  • Temporary files in %TEMP% with .ser or .bin extensions.
  • Modified system binaries (e.g., cmd.exe or powershell.exe spawned by LOCAL SERVICE).

• Process IOCs:

  • java.exe spawning cmd.exe or powershell.exe.
  • Unusual child processes of AllegraService.exe.

Detection Engineering

YARA Rule

rule CVE_2024_5579_Deserialization {
    meta:
        description = "Detects malicious serialized Java objects targeting Allegra renderFieldMatch"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-5579"
    strings:
        $java_serial = { AC ED 00 05 }  // Java serialization magic bytes
        $gadget_chain = /commons-collections|commons-beanutils|commons-logging/
    condition:
        $java_serial at 0 and any of ($gadget_chain)
}

Sigma Rule

title: CVE-2024-5579 Allegra Deserialization Attempt
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects POST requests to Allegra renderFieldMatch with binary data
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/allegra/renderFieldMatch'
        cs-content-type: 'application/octet-stream'
    condition: selection
falsepositives:
    - Legitimate binary uploads (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-5579 Allegra Deserialization Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/allegra/renderFieldMatch"; http_uri; content:"|ac ed 00 05|"; depth:4; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the renderFieldMatch endpoint if not required.
2. Apply input validation to reject binary data (allow only JSON/XML).
3. Upgrade to a patched version once available (monitor vendor advisories).

Long-term Measures:

• Implement a Java deserialization filter (e.g., JEP-290).
• Use a Web Application Firewall (WAF) to block serialized objects.
• Conduct regular security audits and penetration testing.

Workaround:

• Restrict access to Allegra via VPN or IP whitelisting.
• Run Allegra with minimal privileges (not LOCAL SERVICE).

Valters IT