Detect Fortinet FortiOS Sensitive Information Exposure (CVE-2025-68686) in Splunk
CVE-2025-68686 is an Exposure of Sensitive Information to an Unauthorized Actor vulnerability (CWE-200) in Fortinet FortiOS, added to CISA's Known Exploited Vulnerabilities catalog. Unauthorized actors may be able to access sensitive information exposed by affected FortiOS instances, potentially including configuration data, credentials, session tokens, or internal system details that could facilitate further compromise. This detection focuses on identifying anomalous access to FortiOS management interfaces, unusual API/CLI enumeration behavior, and downstream indicators of information disclosure abuse such as suspicious authentication following reconnaissance against exposed FortiOS endpoints.
MITRE ATT&CK
SPL Detection Query
index=network_firewall sourcetype=fortinet:fortigate
| eval mgmt_action=case(match(_raw,"(?i)login"),"login", match(_raw,"(?i)config"),"config", match(_raw,"(?i)backup"),"backup", match(_raw,"(?i)download"),"download", 1=1,"other")
| where mgmt_action!="other"
| bin _time span=1h
| stats count as request_count values(mgmt_action) as actions dc(user) as unique_users by src_ip, dest_ip, _time
| where request_count > 20
| sort - request_countFlags bursts of FortiOS administrative/management log activity per source IP within an hourly window, consistent with attempts to enumerate or extract sensitive information related to CVE-2025-68686.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Authorized config backup automation
- IT staff performing scheduled maintenance
- Security scanning traffic from approved scanners
- High-traffic MSP management consoles managing multiple tenants
Other platforms for CVE-2025-68686
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 high-volume FortiOS admin API access
Expected signal: Multiple HTTP GET requests to /api/v2/cmdb/* endpoint from a single source IP within a short time window, logged in firewall/proxy logs.
- Test 2Simulate FortiOS config backup enumeration
Expected signal: Repeated backup/config-related HTTP requests logged in FortiOS event logs and network proxy logs.
- Test 3Simulate SSL-VPN portal session enumeration
Expected signal: Multiple failed/attempted SSL-VPN login events logged with consistent source IP within a short window.
References (4)
- https://fortiguard.fortinet.com/psirt/FG-IR-25-934
- 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-2025-68686
Response Playbook
Triage
- Confirm the affected FortiOS device version against Fortinet's advisory FG-IR-25-934 to verify exposure to CVE-2025-68686.
- Review management interface (HTTPS admin, SSL-VPN portal) access logs for the affected device over the past 30 days for anomalous source IPs or unusual request volumes.
- Cross-reference alerting source IPs against known scanner/threat intel feeds and internal asset inventory to distinguish authorized administration from suspicious external access.
- Check whether the FortiOS management interface is internet-facing; if so, treat as high priority given active KEV exploitation status.
Containment
- Restrict or disable internet-facing access to FortiOS administrative interfaces (HTTPS admin, SSL-VPN management) via local-in policies or trusted host restrictions.
- Rotate all credentials, API tokens, and certificates that may have been exposed via the affected FortiOS instance, then apply Fortinet's patch per FG-IR-25-934.
Evidence Collection
- Export FortiOS event logs, admin login logs, and configuration change history for the affected time window for forensic review.
- Capture full packet captures or proxy logs for sessions to/from suspicious source IPs interacting with the management interface, preserving timestamps and payload sizes.
Escalation Criteria
- !Escalate immediately if evidence shows successful extraction of configuration data, credentials, or VPN session data from an internet-facing FortiOS device.
- !Escalate to incident response if the affected device is unpatched, internet-facing, and access patterns match known KEV exploitation TTPs referenced in CISA BOD 26-04 guidance.
Investigation Guide
Related Techniques
Forensic Artifacts
- >
FortiOS admin/webadmin access logs (event.log, elog entries) - >
SSL-VPN portal authentication and session logs - >
Configuration change history (diff logs) and backup file access timestamps
Tuning Guidance
Baseline normal administrative access patterns per FortiOS device (expected admin source IPs, typical request volume, scheduled backup windows) before enabling alerting thresholds. Exclude known MSP management IPs and vulnerability scanning ranges. Adjust the request-count threshold (default 20/hour) based on organizational admin activity volume, and prioritize alerts on internet-facing management interfaces per CISA BOD 26-04 guidance.
Hunting Queries
Hunts for repeated or bulk access to FortiOS configuration/API endpoints that may indicate information disclosure activity related to CVE-2025-68686.
CommonSecurityLog
| where DeviceVendor has "Fortinet"
| where isnotempty(RequestURL)
| where RequestURL has_any ("cmdb", "api", "backup")
| summarize count() by SourceIP, RequestURL, bin(TimeGenerated, 1h)
| order by count_ descindex=network_firewall sourcetype=fortinet:fortigate url=*cmdb* OR url=*api* OR url=*backup*
| stats count by src_ip, url, _time
| sort - countAtomic Red Team Tests
Generates repeated HTTP requests to a lab FortiOS-like management API path to simulate enumeration/extraction behavior for detection validation.
Command
for i in $(seq 1 30); do curl -sk -o /dev/null -w '%{http_code}\n' https://<lab-fortios-ip>/api/v2/cmdb/system/status; doneCleanup
No persistent changes made; clear local curl history if desired: history -cExpected Telemetry
Multiple HTTP GET requests to /api/v2/cmdb/* endpoint from a single source IP within a short time window, logged in firewall/proxy logs.
Expected Detection
KQL/SPL/QRadar rules should trigger on request_count > 20 within the 1-hour bin for the source IP.
Simulates repeated attempts to access configuration backup endpoints on a lab FortiOS management interface.
Command
for i in $(seq 1 25); do curl -sk -o /dev/null https://<lab-fortios-ip>/api/v2/monitor/system/config-backup; sleep 1; doneCleanup
No persistent state changes; no cleanup required beyond clearing shell history.Expected Telemetry
Repeated backup/config-related HTTP requests logged in FortiOS event logs and network proxy logs.
Expected Detection
Sumo Logic and Chronicle YARA-L rules should flag the source IP for exceeding the config/backup action threshold.
Simulates repeated login attempts against a lab FortiOS SSL-VPN portal to emulate credential/session enumeration tied to information exposure.
Command
1..25 | ForEach-Object { Invoke-WebRequest -Uri 'https://<lab-fortios-ip>/remote/login' -Method POST -Body @{username='testuser';password='testpass'} -SkipCertificateCheck -UseBasicParsing | Out-Null; Start-Sleep -Seconds 1 }Cleanup
No persistent accounts or sessions created on the lab device; verify no residual sessions remain via FortiOS admin console.Expected Telemetry
Multiple failed/attempted SSL-VPN login events logged with consistent source IP within a short window.
Expected Detection
CrowdStrike CQL and QRadar AQL rules should alert on the elevated event count for admin/login activity from the source IP.