CVE-2024-22394: SonicWall SonicOS Auth Bypass Vulnerability

CVE-2024-22394 Overview

An improper authentication vulnerability has been identified in the SonicWall SonicOS SSL-VPN feature that, under specific conditions, could allow a remote attacker to bypass authentication mechanisms entirely. This authentication bypass flaw represents a significant security risk as it enables unauthorized access to protected network resources without requiring valid credentials.

The vulnerability is classified as an Authentication Bypass (CWE-287), which occurs when an application fails to properly verify the identity of users attempting to access protected resources. In the context of SSL-VPN infrastructure, this type of vulnerability is particularly dangerous as VPN services are typically internet-facing and designed to provide secure remote access to internal networks.

Critical Impact

Remote attackers can bypass SSL-VPN authentication to gain unauthorized access to protected internal networks without valid credentials, potentially compromising confidentiality, integrity, and availability of enterprise resources.

Affected Products

• SonicWall SonicOS version 7.1.1-7040
• SonicWall NSA Series (NSA 2700, NSA 3700, NSA 4700, NSA 5700, NSA 6700)
• SonicWall NSSP Series (NSSP 10700, NSSP 11700, NSSP 13700)
• SonicWall NSv Series (NSv 270, NSv 470, NSv 870)
• SonicWall TZ Series (TZ270W, TZ370, TZ370W, TZ470, TZ470W, TZ570, TZ570P, TZ570W, TZ670, T2270)

Discovery Timeline

• February 8, 2024 - CVE-2024-22394 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2024-22394

Vulnerability Analysis

This authentication bypass vulnerability exists within the SSL-VPN feature of SonicWall SonicOS. The flaw allows remote attackers to circumvent authentication controls under specific conditions, granting them access to VPN-protected resources without presenting valid credentials.

The vulnerability is network-accessible, meaning attackers can exploit it remotely without requiring any prior authentication or user interaction. Successful exploitation results in complete compromise of confidentiality, integrity, and availability of the affected system and the networks it protects.

SSL-VPN appliances serve as critical network perimeter security devices, making this vulnerability particularly concerning for enterprise environments. An attacker exploiting this flaw could potentially gain the same level of network access as a legitimately authenticated VPN user, enabling lateral movement within the internal network.

Root Cause

The root cause of CVE-2024-22394 is an improper authentication implementation (CWE-287) in the SonicOS SSL-VPN feature. This classification indicates that the authentication mechanism fails to properly verify user identity under certain conditions.

Authentication bypass vulnerabilities typically arise from logic flaws in the authentication flow, improper session handling, or insufficient validation of authentication tokens. In this case, the specific conditions that trigger the bypass are limited to firmware version SonicOS 7.1.1-7040, suggesting a regression or flaw introduced in this particular release.

Attack Vector

The attack vector for this vulnerability is network-based, requiring no privileges, authentication, or user interaction. An attacker with network access to the SSL-VPN portal could exploit this vulnerability to bypass authentication and gain unauthorized access.

The attack scenario involves:

1. Attacker identifies an exposed SonicWall SSL-VPN portal running vulnerable firmware version 7.1.1-7040
2. Attacker crafts requests that trigger the specific conditions enabling authentication bypass
3. The SonicOS SSL-VPN feature fails to properly validate the authentication attempt
4. Attacker gains access to VPN-protected network resources without valid credentials

Due to the sensitive nature of this vulnerability and responsible disclosure practices, specific exploitation techniques are not detailed here. Organizations should consult the SonicWall Vulnerability Advisory SNWLID-2024-0003 for technical details and remediation guidance.

Detection Methods for CVE-2024-22394

Indicators of Compromise

• Unexpected or anomalous SSL-VPN authentication events without corresponding valid credential submissions
• VPN session establishments from unusual geographic locations or IP addresses
• Authentication log entries showing successful logins without proper credential validation sequences
• Unusual patterns of internal network access from VPN-connected sessions that don't match normal user behavior

Detection Strategies

• Monitor SonicWall firewall logs for SSL-VPN authentication anomalies and unexpected session establishments
• Implement network traffic analysis to identify unusual access patterns from VPN connections
• Deploy intrusion detection systems (IDS) with signatures for authentication bypass attempts targeting SonicWall devices
• Correlate VPN authentication events with identity management systems to identify sessions lacking proper authentication workflows

Monitoring Recommendations

• Enable verbose logging on SonicWall appliances for SSL-VPN authentication events and access attempts
• Configure SIEM alerts for VPN authentication patterns that deviate from established baselines
• Regularly audit VPN session logs for connections that lack corresponding user authentication records
• Implement network segmentation monitoring to detect lateral movement from potentially compromised VPN sessions

How to Mitigate CVE-2024-22394

Immediate Actions Required

• Verify the firmware version running on all SonicWall appliances; devices running SonicOS 7.1.1-7040 are vulnerable
• Apply the security patch provided by SonicWall immediately to all affected devices
• Review VPN access logs for any indicators of unauthorized access or authentication anomalies
• Consider temporarily disabling SSL-VPN functionality on affected devices until patching is complete if business operations permit

Patch Information

SonicWall has released security updates to address this vulnerability. Organizations should immediately upgrade affected devices from firmware version 7.1.1-7040 to a patched version. Detailed patch information and upgrade instructions are available in the SonicWall Vulnerability Advisory SNWLID-2024-0003.

Administrators should follow SonicWall's recommended upgrade procedures, including backing up device configurations before applying updates. Given the critical nature of this vulnerability, patching should be prioritized and performed during the earliest available maintenance window.

Workarounds

• Restrict SSL-VPN portal access to trusted IP ranges using firewall access rules if the portal cannot be immediately patched
• Implement multi-factor authentication (MFA) as an additional layer of protection for VPN access
• Deploy network access control mechanisms to limit the scope of access for VPN-connected users
• Consider using SonicWall's client-based VPN solutions (Global VPN Client) as an alternative to SSL-VPN until patching is complete

# Verify SonicOS firmware version via CLI
show version

# Check SSL-VPN status and configuration
show ssl-vpn status

# Review active VPN sessions for anomalies
show vpn sessions