CVE-2023-27997:

Heap-based buffer overflow vulnerability in FortiOS and FortiProxy SSL-VPN allows remote code execution.

Score
A numerical rating that indicates how dangerous this vulnerability is.

9.8Critical

Published Date:Jun 13, 2023
CISA KEV Date:Jun 13, 2023
Industries Affected:20

Threat Predictions

EPSS Score:91.2
EPSS Percentile:100%

Exploitability

Score:3.9
Attack Vector:NETWORK
Attack Complexity:LOW
Privileges Required:NONE
User Interaction:NONE
Scope:UNCHANGED

Impact

Score:5.9
Confidentiality Impact:HIGH
Integrity Impact:HIGH
Availability Impact:HIGH

Description Preview

Heap-based buffer overflow vulnerability in FortiOS and FortiProxy SSL-VPN allows remote code execution.

Overview

This vulnerability (CVE-2023-27997) is a heap-based buffer overflow in the SSL-VPN functionality of FortiOS and FortiProxy products. The issue occurs when processing specifically crafted requests, allowing attackers to potentially execute arbitrary code with the privileges of the affected service. Since SSL-VPN services are typically exposed to the internet, this vulnerability presents a significant risk as it can be exploited remotely without authentication. Successful exploitation could lead to complete system compromise, allowing attackers to gain unauthorized access to the network, intercept traffic, or use the compromised system as a launching point for further attacks.

Remediation

To address this vulnerability, organizations should:
1. Update to the following fixed versions or later:
FortiOS: 7.2.5+, 7.0.12+, 6.4.13+, 6.2.15+ (or newer)
FortiProxy: 7.2.4+, 7.0.10+, 2.0.13+ (or newer)
2. If immediate patching is not possible, consider temporarily disabling SSL-VPN functionality until updates can be applied.
3. Implement network segmentation to limit the potential impact of exploitation.
4. Monitor logs for suspicious SSL-VPN access attempts.
5. Implement additional network security controls such as IP restrictions for VPN access where possible.
6. Follow Fortinet security best practices for hardening FortiOS and FortiProxy deployments.