CVE-2024-7595: GRE Protocol Auth Bypass Vulnerability

CVE-2024-7595 Overview

GRE and GRE6 Protocols (RFC2784) do not validate or verify the source of a network packet allowing an attacker to spoof and route arbitrary traffic via an exposed network interface that can lead to spoofing, access control bypass, and other unexpected network behaviors.

Critical Impact

This vulnerability allows attackers to perform spoofing and access control bypass, impacting network traffic integrity and security.

Affected Products

• ietf generic_routing_encapsulation
• ietf generic_routing_encapsulation6

Discovery Timeline

• 2025-02-05 - CVE CVE-2024-7595 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2024-7595

Vulnerability Analysis

The vulnerability arises from the lack of source validation in the GRE and GRE6 protocols as defined by RFC2784. This allows malicious actors to spoof source addresses and send unauthorized traffic, potentially bypassing network security controls.

Root Cause

The core issue is the absence of packet source verification, which results in the ability to forge packet origins.

Attack Vector

The attack vector is network-based, allowing remote attackers to exploit the weak protocol validation.

// Example exploitation code (sanitized)
void send_spoofed_packet() {
    char packet[GRE_PACKET_SIZE];
    // Prepare GRE packet with spoofed source
    prepare_gre_packet(packet, SPOOFED_SOURCE_ADDRESS);
    // Send packet over network
    send_packet_over_network(packet);
}

Detection Methods for CVE-2024-7595

Indicators of Compromise

• Unusual GRE packets from unexpected network sources
• Increased network traffic indicating routing anomalies
• Alerts from network monitoring tools about spoofing attempts

Detection Strategies

Utilize IDS/IPS systems to monitor GRE traffic and flag anomalies. Implement network flow analysis to detect unusual patterns synonymous with spoofing attacks.

Monitoring Recommendations

Regularly inspect GRE traffic for irregularities. Set up alerts for mismatches in expected and actual packet sources.

How to Mitigate CVE-2024-7595

Immediate Actions Required

• Implement packet filtering to drop packets with spoofed sources
• Configure network devices to log and alert on unusual GRE traffic patterns
• Use access control lists (ACLs) to restrict GRE traffic to known sources

Patch Information

Consult with your network device vendor for any available updates or patches that address this issue.

Workarounds

Implement GRE source address validation using firewall rules or network equipment settings to ensure only legitimate sources are allowed.

# Configuration example
iptables -A INPUT -p gre -s ! TRUSTED_SOURCE_ADDRESS -j DROP