CVE-2024-6387: SonicWall SMA 6200 Race Condition Flaw

CVE-2024-6387 Overview

A security regression (CVE-2006-5051) was discovered in OpenSSH's server (sshd). There is a race condition which can lead sshd to handle some signals in an unsafe manner. An unauthenticated, remote attacker may be able to trigger it by failing to authenticate within a set time period.

Critical Impact

High CVSS score of 8.1. Exploiting this vulnerability could allow an attacker to execute code remotely with high impact on confidentiality, integrity, and availability.

Affected Products

• Sonicwall Sma 6200 Firmware
• Arista EOS
• Canonical Ubuntu Linux

Discovery Timeline

• Not Available - Vulnerability discovered by Not Available
• Not Available - Responsible disclosure to Sonicwall
• Not Available - CVE CVE-2024-6387 assigned
• Not Available - Sonicwall releases security patch
• 2024-07-01 - CVE CVE-2024-6387 published to NVD
• 2025-09-30 - Last updated in NVD database

Technical Details for CVE-2024-6387

Vulnerability Analysis

The identified flaw is a race condition in OpenSSH's sshd, potentially allowing signals to be handled in an unsafe manner. This issue arises when unauthenticated access attempts occur within a specific period, potentially leading to remote code execution vulnerabilities in affected systems.

Root Cause

The vulnerability stems from improper signal handling due to a lack of adequate synchronization mechanisms during the authentication failure timeframe.

Attack Vector

The attack vector is network-based, allowing remote unauthenticated attackers to exploit the flaw by altering authentication processes.

// Example exploitation code (sanitized)
void trigger_vuln() {
    if (fork() == 0) {
        // Simulate failed authentication
        sleep(2);
        kill(getppid(), SIGALRM);
    }
    // Vulnerable function
    authenticate_user();
}

Detection Methods for CVE-2024-6387

Indicators of Compromise

• Unusual spikes in failed SSH login attempts
• Anomalous SIGALRM signals in the server logs
• Unexpected sshd process crashes

Detection Strategies

Monitoring inbound network traffic for patterns of failed authentication requests and logging anomalies in sshd behavior can be used to detect potential exploitation attempts.

Monitoring Recommendations

Deploy comprehensive log analysis and intrusion detection systems capable of identifying unusual SSH traffic patterns, specifically targeting authentication failures.

How to Mitigate CVE-2024-6387

Immediate Actions Required

• Apply security patches provided by the vendor as soon as they are available
• Implement strict login throttling policies to reduce exposure to unauthorized access attempts
• Enable enhanced logging to monitor SSH activity

Patch Information

Refer to the vendor's official security patch notes and advisories for detailed patch deployment procedures. Key resources include OpenSSH Commit.

Workarounds

Administrators can temporarily mitigate risk by configuring SSH to use alternative user authentication methods. Until patched, consider restricting SSH access to trusted IP addresses only.

# Configuration example
Match Address 192.168.1.*
    AuthenticationMethods publickey
    PermitRootLogin no
    MaxAuthTries 2