SB20240611271 - MitM attack in Fortinet FortiClient
Published: June 11, 2024 Updated: April 2, 2025
Security Bulletin ID
SB20240611271
Severity
Medium
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Adjecent network
Highest impact
Data manipulation
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 security vulnerability.
1) Man-in-the-Middle (MitM) attack (CVE-ID: CVE-2024-3661)
The vulnerability allows a remote attacker to perform MitM attack.
The vulnerability exists due to way the VPN client handles routes advertised by the DHCP server. A remote attacker with access to the local network can route the victim's traffic to a malicious server instead of sending it via a secured channel.
This vulnerability was dubbed "TunnelVision".
Remediation
Install update from vendor's website.
References
- https://datatracker.ietf.org/doc/html/rfc2131#section-7
- https://datatracker.ietf.org/doc/html/rfc3442#section-7
- https://tunnelvisionbug.com/
- https://www.leviathansecurity.com/research/tunnelvision
- https://news.ycombinator.com/item?id=40279632
- https://arstechnica.com/security/2024/05/novel-attack-against-virtually-all-vpn-apps-neuters-their-entire-purpose/
- https://krebsonsecurity.com/2024/05/why-your-vpn-may-not-be-as-secure-as-it-claims/
- https://issuetracker.google.com/issues/263721377
- https://mullvad.net/en/blog/evaluating-the-impact-of-tunnelvision
- https://www.zscaler.com/blogs/security-research/cve-2024-3661-k-tunnelvision-exposes-vpn-bypass-vulnerability
- https://lowendtalk.com/discussion/188857/a-rogue-dhcp-server-within-your-network-can-and-will-hijack-your-vpn-traffic
- https://news.ycombinator.com/item?id=40284111
- https://www.agwa.name/blog/post/hardening_openvpn_for_def_con
- https://www.theregister.com/2024/05/07/vpn_tunnelvision_dhcp/
- https://www.fortiguard.com/psirt/FG-IR-24-170