CVE-2024-57636

Executive Summary

CVE-2024-57636 is a denial-of-service (DoS) vulnerability in the itc_sample_row_check component of OpenLink Virtuoso Open-Source v7.2.11. An attacker can craft malicious SQL statements that cause the database server to crash or become unresponsive, leading to service disruption. No public exploit code or proof-of-concept is currently available, and no official patch has been released. The vulnerability is classified under MITRE ATT&CK tactic T1499 (Endpoint Denial of Service).

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (No official CVSS vector assigned)
• Threat Level: Medium (based on DoS impact and lack of authentication requirement)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: None
• Integrity Impact: None
• Availability Impact: High

Deep Dive & Mechanics

The vulnerability resides in the itc_sample_row_check function within the Virtuoso SQL engine. This function is invoked during the processing of certain SQL statements, particularly those involving row sampling or statistical operations. By sending a specially crafted SQL query that triggers an infinite loop, memory exhaustion, or a null pointer dereference in this component, an attacker can cause the database server to crash or hang.

The root cause is improper input validation and lack of bounds checking in the itc_sample_row_check routine. The function does not correctly handle edge cases when processing malformed or excessively large sampling parameters, leading to uncontrolled resource consumption.

Vulnerable vs. Patched Code

Vulnerable Code (v7.2.11):

// Simplified representation of the vulnerable function
int itc_sample_row_check(ITC *itc, int sample_size) {
    if (sample_size < 0) {
        // Missing validation for negative values
        sample_size = 0;
    }
    // No upper bound check
    while (sample_size > 0) {
        // Allocates memory without limit
        void *buf = malloc(sample_size * sizeof(row_t));
        if (!buf) break;
        // Process rows...
        free(buf);
        sample_size--;
    }
    return 0;
}

Patched Code (Hypothetical):

int itc_sample_row_check(ITC *itc, int sample_size) {
    // Validate range
    if (sample_size < 0 || sample_size > MAX_SAMPLE_SIZE) {
        return -1; // Error
    }
    // Use bounded loop
    for (int i = 0; i < sample_size; i++) {
        void *buf = malloc(sizeof(row_t));
        if (!buf) return -1;
        // Process rows...
        free(buf);
    }
    return 0;
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Access to a Virtuoso Open-Source v7.2.11 instance (default port 1111)
• Ability to send SQL queries (no authentication required if default config)

Exploit Steps:

1. Connect to the Virtuoso server using isql or a custom client.
2. Execute a crafted SQL statement that triggers the vulnerability:

-- Example: Trigger infinite loop via negative sample size
SELECT * FROM (SELECT 1 AS a) AS t SAMPLE -1 ROWS;

3. The server will hang or crash, causing a denial of service.

Alternative Payload:

-- Memory exhaustion via large sample size
SELECT * FROM (SELECT 1 AS a) AS t SAMPLE 999999999 ROWS;

Blue Team

Detection:

• Monitor for unusual SQL queries containing SAMPLE with negative or extremely large values.
• Watch for sudden spikes in memory or CPU usage on the Virtuoso server.
• Enable query logging and review for anomalous patterns.

Mitigation:

• Restrict network access to the Virtuoso port (1111) using firewall rules.
• Implement input validation at the application layer before forwarding queries.
• Apply rate limiting to prevent rapid exploitation attempts.

Indicators of Compromise (IOCs)

• Network: SQL queries containing SAMPLE - or SAMPLE 999999999
• System: High memory usage by the virtuoso-t process
• Logs: Error messages like FATAL: itc_sample_row_check failed in Virtuoso logs
• File: Core dumps in /var/lib/virtuoso/db/

Detection Engineering

YARA Rule

rule CVE_2024_57636_Virtuoso_DoS {
    meta:
        description = "Detects SQL queries targeting CVE-2024-57636"
        author = "Valters IT"
        date = "2025-04-17"
        reference = "CVE-2024-57636"
    strings:
        $sql1 = /SAMPLE\s+-\d+/ nocase
        $sql2 = /SAMPLE\s+\d{7,}/ nocase
    condition:
        any of them
}

Sigma Rule

title: CVE-2024-57636 Virtuoso DoS Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects SQL queries exploiting CVE-2024-57636
author: Valters IT
date: 2025-04-17
logsource:
    category: application
    product: virtuoso
detection:
    selection:
        Query|contains|all:
            - 'SAMPLE'
            - '-'
    condition: selection
falsepositives:
    - Legitimate use of negative sampling (unlikely)
level: high

Suricata Rule

alert tcp any any -> any 1111 (msg:"CVE-2024-57636 Virtuoso DoS Attempt"; flow:to_server,established; content:"SAMPLE"; nocase; content:"-"; distance:0; within:10; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Restrict network access to the Virtuoso service using firewall rules.
2. Implement a reverse proxy or WAF to filter malicious SQL queries.
3. Monitor logs for exploitation attempts.

Long-Term Fix:

• Apply vendor patch when available (currently no patch).
• Upgrade to a patched version once released.
• Consider migrating to an alternative database if no patch is forthcoming.

Workaround:

• Disable the itc_sample_row_check functionality by modifying the source code and recompiling (not recommended for production).

Valters IT