CVE-2024-21762: Fortinet FortiProxy RCE Vulnerability

CVE-2024-21762 Overview

A out-of-bounds write in Fortinet FortiOS versions 7.4.0 through 7.4.2, 7.2.0 through 7.2.6, 7.0.0 through 7.0.13, 6.4.0 through 6.4.14, 6.2.0 through 6.2.15, 6.0.0 through 6.0.17, FortiProxy versions 7.4.0 through 7.4.2, 7.2.0 through 7.2.8, 7.0.0 through 7.0.14, 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 allows an attacker to execute unauthorized code or commands via specifically crafted requests.

Critical Impact
This vulnerability could allow remote attackers to execute arbitrary code, posing significant risks to system integrity and data confidentiality.

Affected Products

Fortinet FortiOS
Fortinet FortiProxy

Discovery Timeline

2024-02-09 - CVE CVE-2024-21762 published to NVD
2025-10-24 - Last updated in NVD database

Technical Details for CVE-2024-21762

Vulnerability Analysis

The vulnerability arises from improper bounds checking on memory operations, leading to an out-of-bounds write. This condition allows the injection and execution of arbitrary code.

Root Cause

The root cause is a failure in input validation when parsing network packets, which allows overwriting memory beyond its intended buffer limits.

Attack Vector

This vulnerability can be exploited remotely through network access, requiring no prior authentication.

// Example exploitation code (sanitized)
#include <stdio.h>
#include <string.h>

void vulnerable_function(char *input) {
    char buffer[64];
    // Lack of bounds checking
    strcpy(buffer, input);
}

int main(int argc, char *argv[]) {
    if (argc != 2) {
        printf("Usage: %s <input>\n", argv[0]);
        return 1;
    }
    vulnerable_function(argv[1]);
    return 0;
}

Detection Methods for CVE-2024-21762

Indicators of Compromise

Unexpected network traffic patterns
Unusual process execution
Memory corruption errors in logs

Detection Strategies

Utilize endpoint protection solutions like SentinelOne to monitor for anomaly-based behaviors and potential memory corruptions indicative of exploitation attempts.

Monitoring Recommendations

Implement network monitoring to detect abnormal traffic and use Host Intrusion Detection Systems (HIDS) to observe unauthorized code execution activities.

How to Mitigate CVE-2024-21762

Immediate Actions Required

Update to the latest patched versions of FortiOS and FortiProxy
Restrict network access to vulnerable services
Implement application-layer firewalls to filter malicious inputs

Patch Information

Refer to the vendor advisory for patch details: Fortinet Advisory.

Workarounds

Temporary workarounds involve configuring network level restrictions to limit exposure until patches are applied.

bash

# Configuration example
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP