CVE-2023-41677: Fortinet FortiProxy Auth Bypass Vulnerability

CVE-2023-41677 Overview

CVE-2023-41677 is a high-severity vulnerability involving insufficiently protected credentials in Fortinet FortiProxy and FortiOS products. This vulnerability allows an attacker to execute unauthorized code or commands via a targeted social engineering attack. The flaw stems from improper credential protection mechanisms (CWE-522), enabling malicious actors to potentially compromise authentication credentials through carefully crafted attacks that require user interaction.

Critical Impact

Successful exploitation could allow attackers to execute unauthorized code or commands, potentially leading to complete system compromise of affected Fortinet security appliances.

Affected Products

• Fortinet FortiProxy 7.4.0, 7.2.0 through 7.2.6, 7.0.0 through 7.0.12, 2.0.0 through 2.0.13, 1.2.0 through 1.2.13, 1.1.0 through 1.1.6, 1.0.0 through 1.0.7
• Fortinet FortiOS 7.4.0 through 7.4.1, 7.2.0 through 7.2.6, 7.0.0 through 7.0.12
• Fortinet FortiOS 6.4.0 through 6.4.14, 6.2.0 through 6.2.15, 6.0.0 through 6.0.17

Discovery Timeline

• 2024-04-09 - CVE-2023-41677 published to NVD
• 2024-12-12 - Last updated in NVD database

Technical Details for CVE-2023-41677

Vulnerability Analysis

The insufficiently protected credentials vulnerability in FortiProxy and FortiOS represents a significant security risk to organizations relying on these Fortinet products for network security. The vulnerability exists due to inadequate protection of sensitive credential information within the affected products.

When credentials are not properly protected during storage, transmission, or processing, attackers can potentially intercept or extract this sensitive information. In the context of CVE-2023-41677, the vulnerability requires user interaction through social engineering, meaning attackers must craft convincing scenarios to manipulate users into actions that expose their credentials.

The network-based attack vector means that exploitation can occur remotely without requiring prior access to the target system. However, the user interaction requirement provides some mitigation, as attacks cannot be fully automated without human participation.

Root Cause

The root cause of this vulnerability is CWE-522: Insufficiently Protected Credentials. This weakness occurs when the application transmits or stores authentication credentials using an insecure method that could allow them to be intercepted or obtained. In the affected Fortinet products, credential handling mechanisms fail to adequately protect sensitive authentication data, creating an exploitable attack surface.

Attack Vector

The attack vector for CVE-2023-41677 is network-based and requires user interaction. An attacker would typically:

1. Identify target organizations using vulnerable FortiProxy or FortiOS versions
2. Craft targeted social engineering campaigns (such as phishing emails or malicious websites)
3. Trick users into performing actions that expose their credentials
4. Capture insufficiently protected credentials through the vulnerability
5. Leverage obtained credentials to execute unauthorized code or commands on affected systems

The social engineering component is critical to successful exploitation, making security awareness training an important defensive measure alongside technical mitigations.

Detection Methods for CVE-2023-41677

Indicators of Compromise

• Unusual authentication attempts or credential usage patterns on FortiProxy/FortiOS management interfaces
• Unexpected administrative commands or configuration changes on Fortinet appliances
• Anomalous network traffic patterns to or from Fortinet devices, particularly involving credential data
• User reports of phishing attempts targeting Fortinet administrator credentials

Detection Strategies

• Implement network monitoring to detect suspicious traffic patterns targeting Fortinet management interfaces
• Enable comprehensive logging on FortiProxy and FortiOS devices and forward logs to SIEM for analysis
• Monitor for unauthorized configuration changes or command execution on affected devices
• Deploy email security solutions to detect and block social engineering attempts targeting users

Monitoring Recommendations

• Regularly audit authentication logs on affected Fortinet products for suspicious activity
• Configure alerting for failed authentication attempts and unusual access patterns
• Monitor for indicators of credential harvesting or unauthorized access attempts
• Implement behavioral analytics to detect anomalous administrator activities

How to Mitigate CVE-2023-41677

Immediate Actions Required

• Identify all FortiProxy and FortiOS installations within your environment and verify version numbers
• Review the FortiGuard Security Advisory for specific remediation guidance
• Prioritize patching of internet-facing and critical Fortinet appliances
• Implement additional security awareness training focused on social engineering attacks

Patch Information

Fortinet has released security updates to address this vulnerability. Organizations should consult the official FortiGuard Security Advisory FG-IR-23-493 for detailed patch information and upgrade paths specific to their deployed versions.

For FortiProxy, upgrade to patched versions as specified in the advisory. For FortiOS, similarly consult the advisory for recommended target versions that address this credential protection vulnerability.

Workarounds

• Restrict management interface access to trusted networks and IP addresses only
• Implement multi-factor authentication (MFA) for all administrative access to Fortinet devices
• Enhance security awareness training to help users recognize and resist social engineering attacks
• Consider implementing additional network segmentation to limit the impact of potential credential compromise

# Example: Restrict management access to trusted networks on FortiOS
# Access the FortiOS CLI and configure trusted hosts
config system admin
    edit "admin"
        set trusthost1 10.0.0.0 255.255.255.0
        set trusthost2 192.168.1.0 255.255.255.0
    next
end