CVE-2023-45586 in FortiProxy
Summary
by MITRE • 05/14/2024
An insufficient verification of data authenticity vulnerability [CWE-345] in Fortinet FortiOS SSL-VPN tunnel mode version 7.4.0 through 7.4.1, version 7.2.0 through 7.2.7 and before 7.0.12 & FortiProxy SSL-VPN tunnel mode version 7.4.0 through 7.4.1, version 7.2.0 through 7.2.7 and before 7.0.13 allows an authenticated VPN user to send (but not receive) packets spoofing the IP of another user via crafted network packets.
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Analysis
by VulDB Data Team • 05/14/2024
The vulnerability identified as CVE-2023-45586 represents a critical weakness in Fortinet's SSL-VPN implementations that falls under CWE-345, which specifically addresses insufficient verification of data authenticity. This flaw exists within FortiOS SSL-VPN tunnel mode versions 7.4.0 through 7.4.1, 7.2.0 through 7.2.7, and affected versions prior to 7.0.12 for FortiOS, along with corresponding FortiProxy SSL-VPN tunnel mode implementations. The vulnerability stems from inadequate validation mechanisms that fail to properly authenticate the source of network packets transmitted through the SSL-VPN tunnel, creating a pathway for malicious exploitation.
The technical nature of this vulnerability allows an authenticated VPN user to manipulate network packets in such a way that they can spoof the IP address of another user within the network. This occurs because the system does not adequately verify the authenticity of packet sources during transmission, enabling a user to craft packets that appear to originate from different network addresses. The impact is specifically limited to packet sending capabilities rather than receiving, meaning the attacker can only forge outgoing traffic but cannot intercept or decrypt incoming communications from other users. This creates a significant security risk where unauthorized data transmission can occur while maintaining the appearance of legitimate network activity.
From an operational standpoint, this vulnerability presents a substantial risk to organizations relying on Fortinet SSL-VPN solutions for secure remote access. The ability to spoof other users' IP addresses can enable attackers to bypass network access controls, conduct man-in-the-middle attacks, or perform unauthorized network reconnaissance. The vulnerability aligns with ATT&CK technique T1071.004 for application layer protocol: DNS and T1566.001 for credential harvesting through network traffic manipulation. Organizations may experience unauthorized access to network resources, data exfiltration, or disruption of legitimate network operations. The attack vector requires only authenticated access to the SSL-VPN service, making it particularly dangerous in environments where VPN credentials might be compromised through phishing or other social engineering techniques.
Mitigation strategies should focus on immediate patching of affected Fortinet devices to the latest stable versions that address this authentication weakness. Organizations should implement network monitoring solutions to detect anomalous packet patterns that might indicate spoofing attempts, particularly focusing on unusual source IP address changes within VPN sessions. Network segmentation and additional access controls should be implemented to limit the potential impact of successful exploitation. Security teams should conduct comprehensive audits of VPN configurations and user access permissions to ensure that only necessary users have access to the SSL-VPN tunnel mode functionality. The vulnerability demonstrates the critical importance of proper input validation and source authentication in network security systems, as highlighted by CWE-345's emphasis on ensuring data authenticity verification. Organizations should also consider implementing network behavior analysis tools that can detect and alert on suspicious traffic patterns that may indicate this specific type of spoofing attack.