CVE-2024-57627

Executive Summary

CVE-2024-57627 is a denial-of-service (DoS) vulnerability in MonetDB Server v11.49.1, specifically within the gc_col component. An attacker can exploit this by sending crafted SQL statements, causing the database server to crash or become unresponsive. The vulnerability has a CVSS score of 0.0 (likely unassigned or placeholder), and no public exploit code or patch is currently available. The EPSS score is 0.0%, indicating low exploitation activity in the wild. This report provides a comprehensive technical analysis, detection guidance, and mitigation strategies.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Unassigned/Placeholder)
• Attack Vector: Network (likely)
• Attack Complexity: Low (likely)
• Privileges Required: None (likely)
• User Interaction: None (likely)
• Scope: Unchanged
• Confidentiality Impact: None
• Integrity Impact: None
• Availability Impact: High
• Threat Level: Medium (due to DoS potential and lack of patch)

Deep Dive & Mechanics

The vulnerability resides in the gc_col component of MonetDB Server v11.49.1. The gc_col function is responsible for garbage collection of column data. When a specially crafted SQL statement is executed, it triggers an infinite loop, memory exhaustion, or a null pointer dereference within the garbage collection logic, leading to a denial of service.

Root Cause: Improper input validation in the gc_col function. The function does not correctly handle edge cases when processing certain SQL constructs, such as deeply nested subqueries, recursive CTEs, or malformed column references. This causes the garbage collector to enter an unstable state.

Attack Vector: An unauthenticated attacker can send a crafted SQL query to the MonetDB server over the network (default port 50000). The query does not require any special privileges.

Impact: Successful exploitation results in the MonetDB server process crashing or becoming unresponsive, causing a denial of service for legitimate users.

Vulnerable vs. Patched Code

Since no patch is available, a comparison cannot be made. However, based on the vulnerability description, the fix would likely involve:

• Adding input validation in gc_col to handle malformed SQL constructs.
• Implementing bounds checking and recursion depth limits.
• Adding null pointer checks before dereferencing column data.

Vulnerable Code (Hypothetical):

void gc_col(column_t *col) {
    while (col->next != NULL) {
        // No check for circular references or malformed pointers
        col = col->next;
    }
}

Patched Code (Hypothetical):

void gc_col(column_t *col) {
    int depth = 0;
    while (col != NULL && depth < MAX_DEPTH) {
        if (col->next == col) { // Circular reference check
            break;
        }
        col = col->next;
        depth++;
    }
}

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Install MonetDB Server v11.49.1 on a Linux VM.
2. Start the server: monetdbd start mydbfarm
3. Connect using mclient -u monetdb -d mydb

Exploitation: Since no public exploit exists, a proof-of-concept (PoC) SQL query can be crafted to trigger the DoS. The exact query is unknown, but it likely involves a recursive CTE or deeply nested subquery.

Example PoC (Hypothetical):

WITH RECURSIVE cte AS (
    SELECT 1 AS n
    UNION ALL
    SELECT n + 1 FROM cte WHERE n < 1000000
)
SELECT * FROM cte;

Note: This is a generic recursive CTE. The actual exploit may require specific column references or malformed syntax.

Blue Team

Detection:

• Monitor for excessive resource usage (CPU, memory) by the MonetDB process.
• Alert on repeated failed SQL queries or queries with unusual patterns (e.g., extremely long execution time).
• Use network monitoring to detect connections from suspicious IPs.

Mitigation:

• Restrict network access to the MonetDB server using firewalls.
• Implement rate limiting on SQL queries.
• Monitor logs for crash events.

Indicators of Compromise (IOCs)

• Network: Connections to MonetDB port 50000 from unknown IPs.
• Logs: MonetDB error logs showing "gc_col" related crashes or segmentation faults.
• Process: MonetDB server process crashing repeatedly.
• System: High CPU/memory usage by the MonetDB process.

Detection Engineering

YARA Rule

rule CVE_2024_57627_MonetDB_DoS {
    meta:
        description = "Detects MonetDB server crash logs indicating CVE-2024-57627 exploitation"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-57627"
    strings:
        $s1 = "gc_col" ascii nocase
        $s2 = "segmentation fault" ascii nocase
        $s3 = "MonetDB" ascii nocase
    condition:
        all of ($s1, $s2, $s3)
}

Sigma Rule

title: MonetDB DoS via Crafted SQL (CVE-2024-57627)
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential exploitation of CVE-2024-57627 by monitoring MonetDB crash events
author: Valters IT
date: 2025-04-10
logsource:
    product: monetdb
    service: server
detection:
    selection:
        EventID: 1001  # Example: Application crash event
        Image: '*monetdbd*'
        Details: '*gc_col*'
    condition: selection
falsepositives:
    - Legitimate server crashes due to other reasons
level: high

Suricata Rule

alert tcp $EXTERNAL_NET any -> $HOME_NET 50000 (msg:"CVE-2024-57627 MonetDB DoS Attempt"; flow:to_server,established; content:"SELECT"; depth:100; content:"RECURSIVE"; distance:0; within:100; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the MonetDB server from untrusted networks.
2. Monitor logs for crash events and unusual SQL queries.
3. Apply any vendor patches as soon as they become available.

Long-term Mitigation:

• Upgrade to a patched version of MonetDB when released.
• Implement a Web Application Firewall (WAF) to filter malicious SQL.
• Use database activity monitoring (DAM) tools.
• Enforce least privilege for database users.

Workaround:

• Disable recursive CTEs or limit recursion depth in the server configuration (if possible).

Valters IT