Detect Fortinet FortiSandbox OS Command Injection (CVE-2026-25089) in IBM QRadar
Detects potential exploitation of CVE-2026-25089, an OS command injection vulnerability (CWE-78) in Fortinet FortiSandbox that allows an authenticated or remote attacker to execute arbitrary commands on the underlying operating system via crafted input to a vulnerable API/web endpoint. This vulnerability is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog and is subject to BOD 26-04 prioritized remediation timelines. Detection focuses on anomalous shell/process execution spawned from FortiSandbox web/management processes, suspicious HTTP requests containing shell metacharacters against FortiSandbox management interfaces, and post-exploitation command execution artifacts.
MITRE ATT&CK
QRadar Detection Query
SELECT DATEFORMAT(devicetime, 'YYYY-MM-dd HH:mm:ss') AS EventTime, sourceip, destinationip, URL, "Log Source", payload
FROM events
WHERE LOGSOURCETYPENAME(devicetype) ILIKE '%Fortinet%'
AND (URL IMATCHES '.*(;|\\||&&|\\$\\(|`|wget |curl |chmod \\+x).*' OR UTF8(payload) IMATCHES '.*(;|\\||&&|\\$\\(|`|/bin/sh|/bin/bash).*')
LAST 24 HOURSIdentifies FortiSandbox-related events with command-injection payload patterns in the URL or raw payload field, indicative of exploitation attempts against CVE-2026-25089.
Data Sources
Required Tables
False Positives & Tuning
- Authorized red team or vulnerability scanning activity against FortiSandbox
- Payload inspection artifacts from TLS-terminating proxies that alter logged content
- Benign administrative API calls that legitimately include special characters
Other platforms for CVE-2026-25089
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Simulate command injection payload in HTTP request
Expected signal: HTTP access log entry on the FortiSandbox lab appliance (or reverse proxy) showing the request URL with embedded shell metacharacters
- Test 2Simulate payload download via wget from web-server-spawned shell
Expected signal: Process creation event showing wget spawned as a child of a web-server user/process, with associated CommandLine and ParentBaseFileName
- Test 3Simulate reverse shell command execution pattern
Expected signal: Process creation log/EDR telemetry showing sh -c invocation with an unusual parent process (web server user context)
References (4)
- https://fortiguard.fortinet.com/psirt/FG-IR-26-141
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
- https://nvd.nist.gov/vuln/detail/CVE-2026-25089
Response Playbook
Triage
- Confirm the affected FortiSandbox appliance's firmware version against Fortinet's advisory FG-IR-26-141 to determine if it falls within the vulnerable version range
- Review FortiSandbox system logs, web access logs, and CLI audit logs around the alert timeframe for unexpected process spawns, shell invocations, or configuration changes
- Correlate source IP addresses of suspicious requests against known scanning infrastructure, threat intelligence feeds, and prior authorized testing schedules to rule out false positives
- Check for outbound connections from the FortiSandbox device to unfamiliar external IPs/domains that could indicate a reverse shell or payload download following successful injection
Containment
- Isolate the FortiSandbox appliance from untrusted network segments (restrict management interface access to trusted admin subnets only) while investigation proceeds
- If compromise is confirmed, take the device offline or place it in a quarantined VLAN, then follow Fortinet's guidance to apply the patched firmware version referenced in FG-IR-26-141
Evidence Collection
- Export FortiSandbox system event logs, web server access logs, and CLI history covering at least 30 days prior to the earliest detected suspicious activity
- Capture a forensic image or configuration/system snapshot of the appliance (where supported) prior to remediation, and preserve any identified dropped files, cron entries, or unauthorized accounts
Escalation Criteria
- !Evidence of successful command execution (e.g., new unauthorized system accounts, modified cron jobs, unexpected outbound C2-like traffic, or webshell files) warrants immediate escalation to incident response
- !Presence of this device in a network segment with access to sensitive file analysis results, malware samples, or other security tooling should trigger escalation given potential lateral movement risk and the KEV/BOD 26-04 mandated urgency
Investigation Guide
Related Techniques
Forensic Artifacts
- >
FortiSandbox web/API access logs showing crafted requests with shell metacharacters - >
Unexpected child processes (sh, bash, wget, curl) spawned from FortiSandbox web/management daemons - >
New or modified cron jobs, startup scripts, or unauthorized local/system accounts on the appliance - >
Outbound network connections from the FortiSandbox device to unfamiliar external hosts
Tuning Guidance
Baseline normal administrative and integration traffic to FortiSandbox management interfaces to reduce noise from legitimate encoded URL parameters. Exclude known vulnerability scanner IP ranges used for authorized assessments. If FortiSandbox logs are not natively ingested, prioritize onboarding syslog/CEF forwarding from the appliance before relying on this detection, and consider raising confidence to high once verified log field mappings are validated in your environment.
Hunting Queries
Broader hunt for command-execution indicators in FortiSandbox logs over a 30-day window to identify low-and-slow or previously unalerted exploitation attempts.
CommonSecurityLog
| where DeviceProduct has "FortiSandbox"
| where Message has_any ("wget", "curl", "chmod +x", "/bin/sh", "/bin/bash")
| summarize count() by SourceIP, DestinationIP, bin(TimeGenerated, 1h)
| sort by count_ descindex=network sourcetype=fortinet:fortisandbox ("wget" OR "curl" OR "chmod +x" OR "/bin/sh" OR "/bin/bash")
| stats count by src_ip, dest_ip, _time
| sort -countAtomic Red Team Tests
Sends a crafted HTTP request containing shell metacharacters to a lab FortiSandbox instance or mock endpoint to validate log capture and detection logic.
Command
curl -sk "https://LAB-FORTISANDBOX-IP/api/v1/submit?file=test;id;whoami" -o /dev/nullCleanup
No persistent changes made; verify no unintended command execution occurred on the lab target.Expected Telemetry
HTTP access log entry on the FortiSandbox lab appliance (or reverse proxy) showing the request URL with embedded shell metacharacters
Expected Detection
SIEM alert fires from the kql/spl/elastic_eql rules matching shell metacharacter patterns in the request URL
Emulates post-exploitation behavior by having a process resembling the FortiSandbox web daemon spawn wget to fetch a benign test file, validating EDR process-lineage detection.
Command
sudo -u www-data bash -c 'wget -q http://127.0.0.1:8000/testfile.txt -O /tmp/atomic_test_download.txt'Cleanup
rm -f /tmp/atomic_test_download.txtExpected Telemetry
Process creation event showing wget spawned as a child of a web-server user/process, with associated CommandLine and ParentBaseFileName
Expected Detection
CrowdStrike CQL query flags the wget child process spawned from a web-server-context parent
Generates a benign local process chain resembling a shell invocation (sh -c) launched from a web-server-owned account to validate detection of interpreter execution consistent with command injection.
Command
sudo -u www-data sh -c 'echo atomic_test_marker > /tmp/atomic_test_marker.txt'Cleanup
rm -f /tmp/atomic_test_marker.txtExpected Telemetry
Process creation log/EDR telemetry showing sh -c invocation with an unusual parent process (web server user context)
Expected Detection
CrowdStrike CQL and Elastic EQL rules identify the shell interpreter execution originating from a web-server-associated parent process