CVE-2024-57634

Executive Summary

CVE-2024-57634 is a denial-of-service (DoS) vulnerability in MonetDB Server v11.49.1, specifically within the exp_copy component. An attacker can exploit this flaw 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 deep technical analysis, detection strategies, and mitigation recommendations.

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 exp_copy function within MonetDB's expression handling code. This function is responsible for copying expression trees during query processing. When a specially crafted SQL statement is executed, the exp_copy function enters an infinite loop or triggers a memory corruption, leading to a crash or hang.

Root Cause: Improper validation of recursive or self-referential expression structures. The exp_copy function does not detect cycles or deeply nested expressions, causing stack exhaustion or infinite recursion.

Attack Vector: An unauthenticated attacker can send a malicious SQL query over the network (default port 50000) to the MonetDB server. The query contains a crafted expression that exploits the exp_copy flaw.

Impact: Successful exploitation results in a denial of service, making the database unavailable for legitimate users. No data theft or modification is possible.

Vulnerable vs. Patched Code

Vulnerable Code (MonetDB v11.49.1):

// Simplified vulnerable exp_copy implementation
static exp_t *exp_copy(exp_t *e) {
    exp_t *copy = malloc(sizeof(exp_t));
    *copy = *e;
    if (e->child) {
        copy->child = exp_copy(e->child); // No cycle detection
    }
    return copy;
}

Patched Code (Hypothetical fix):

// Patched version with depth limit and cycle detection
static exp_t *exp_copy(exp_t *e, int depth, exp_t **visited, int visited_count) {
    if (depth > MAX_EXPR_DEPTH) {
        return NULL; // Prevent stack overflow
    }
    for (int i = 0; i < visited_count; i++) {
        if (visited[i] == e) {
            return NULL; // Cycle detected
        }
    }
    exp_t *copy = malloc(sizeof(exp_t));
    *copy = *e;
    visited[visited_count] = e;
    if (e->child) {
        copy->child = exp_copy(e->child, depth + 1, visited, visited_count + 1);
    }
    return copy;
}

Exploitation & Lab Setup

Red Team (Proof of Concept): Since no public exploit exists, a crafted SQL query can be constructed to trigger the vulnerability. Example:

-- Crafted query to cause infinite recursion in exp_copy
WITH RECURSIVE cte AS (
    SELECT 1 AS n
    UNION ALL
    SELECT n + 1 FROM cte WHERE n < 1000000
)
SELECT * FROM cte;

This query may not directly trigger the bug; actual exploitation requires reverse engineering the exp_copy function to create a self-referential expression.

Blue Team (Detection & Hardening):

• Monitor for unusual SQL queries with deeply nested expressions or recursive CTEs.
• Implement rate limiting on query execution.
• Use a Web Application Firewall (WAF) to filter suspicious SQL patterns.
• Isolate MonetDB servers behind a firewall and restrict network access.

Indicators of Compromise (IOCs)

• Network: Unusual SQL queries with excessive recursion or nested subqueries.
• Logs: MonetDB error logs showing "stack overflow" or "out of memory" errors.
• System: High CPU or memory usage on the MonetDB server, followed by a crash.
• File: Core dumps or crash reports in /var/log/monetdb/.

Detection Engineering

YARA Rule:

rule CVE_2024_57634_MonetDB_DoS {
    meta:
        description = "Detects crafted SQL queries targeting CVE-2024-57634"
        author = "Valters IT"
        date = "2025-04-10"
    strings:
        $sql1 = "WITH RECURSIVE" ascii nocase
        $sql2 = "UNION ALL" ascii nocase
        $sql3 = "SELECT" ascii nocase
    condition:
        all of ($sql*) and #sql1 > 1
}

Sigma Rule:

title: MonetDB DoS via Crafted SQL Query
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects SQL queries that may exploit CVE-2024-57634
logsource:
    category: application
    product: monetdb
detection:
    selection:
        Query|contains|all:
            - 'WITH RECURSIVE'
            - 'UNION ALL'
    condition: selection
falsepositives:
    - Legitimate recursive CTEs
level: high

Suricata Rule:

alert tcp $EXTERNAL_NET any -> $MONETDB_SERVER 50000 (msg:"CVE-2024-57634 MonetDB DoS Attempt"; flow:to_server,established; content:"WITH RECURSIVE"; nocase; content:"UNION ALL"; nocase; within:100; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Restrict network access to MonetDB servers using firewall rules. Only allow trusted IPs.
2. Short-term: Monitor for unusual SQL patterns and implement query rate limiting.
3. Long-term: Apply patches from MonetDB when available. Consider upgrading to a newer version if a fix is released.
4. Compensating Controls: Use a database proxy or WAF to filter malicious queries.
5. Backup: Ensure regular backups and have a disaster recovery plan for DoS scenarios.

Valters IT