CVE-2026-25089: FortiSandbox Command Injection — Detection and Remediation Guide

---
title: Potential Command Injection in FortiSandbox WEB UI
id: 8a1b2c3d-4e5f-6789-0a1b-2c3d4e5f6789
status: experimental
description: Detects potential command injection attempts against the FortiSandbox WEB UI by identifying shell metacharacters in URL parameters.
references:
  - https://fortiguard.com/encyclopedia?ipsid=0
author: Security Arsenal
date: 2026/06/24
tags:
  - attack.initial_access
  - attack.t1190
logsource:
  category: web
product: fortinet
detection:
  selection:
    c-host|contains: 'sandbox'
    cs-uri-query|contains:
      - '|'
      - ';'
      - '`'
      - '$('
  condition: selection
falsepositives:
  - Legitimate administrative use of special characters (rare)
level: high
---
title: FortiSandbox Web Server Spawning Shell
id: 9b2c3d4e-5f60-7890-1b2c-3d4e5f67890a
status: experimental
description: Detects the FortiSandbox web server process spawning a shell, indicative of successful command injection.
references:
  - https://attack.mitre.org/techniques/T1059/
author: Security Arsenal
date: 2026/06/24
tags:
  - attack.execution
  - attack.t1059.004
logsource:
  category: process_creation
  product: linux
detection:
  selection:
    ParentImage|endswith:
      - '/lighttpd'
      - '/nginx'
      - '/httpd'
    Image|endswith:
      - '/sh'
      - '/bash'
      - '/bin/netcat'
  condition: selection
falsepositives:
  - Administrative debugging via shell (rare)
level: critical

// Hunt for command injection patterns in FortiSandbox Logs
// Assumes FortiSandbox logs are forwarded via Syslog/CEF
Syslog
| where DeviceVendor == "Fortinet"
| where DeviceProduct == "FortiSandbox"
| where SyslogMessage has_any ("sandbox", "fgfm")
| extend ExtractedFields = extract_all(@"(?i)(\||;|&|`|\$\()", Dynamic([0]), SyslogMessage)
| where isnotnull(ExtractedFields[0])
| project TimeGenerated, DeviceName, Facility, SeverityLevel, SyslogMessage, ExtractedFields
| order by TimeGenerated desc

-- Hunt for web server processes spawning shells on Linux endpoints (Appliance investigation)
SELECT Parent.Name AS ParentProcess, Name AS ChildProcess, CommandLine, Pid, PPid, Username
FROM pslist()
WHERE Parent.Name =~ "httpd" OR Parent.Name =~ "nginx" OR Parent.Name =~ "lighttpd"
  AND Name =~ "sh" OR Name =~ "bash" OR Name =~ "nc"

#!/bin/bash
# Remediation script for FortiSandbox CVE-2026-25089
# This script checks the installed version and searches logs for indicators of compromise.

# 1. Check FortiSandbox Version
# Note: 'execute version' is the standard CLI command. Adjust if running via API.
# Assuming SSH access or CLI access context.
echo "[+] Checking FortiSandbox version..."
# This command is simulated for the script context. In reality, run 'get system status' in CLI.
# execute get system status

# 2. Search Web Access Logs for Common Command Injection Characters
# Adjust path based on your specific deployment/log rotation settings.
LOG_FILE="/var/log/lighttpd/access.log"
IOC_PATTERN="[|;`]"

if [ -f "$LOG_FILE" ]; then
    echo "[+] Scanning $LOG_FILE for potential command injection indicators..."
    grep -E "$IOC_PATTERN" "$LOG_FILE" | tail -n 20
else
    echo "[-] Log file not found at $LOG_FILE. Check specific appliance logging paths."
fi

echo "[+] Remediation Recommendation:"
echo "1. Upgrade to the latest FortiSandbox firmware immediately per Fortinet Advisory FG-IR-26-XXX"
echo "2. Restrict WEB UI access to specific management IPs only."
echo "3. Enforce MFA for all administrative access."