Detect Fortinet FortiClient EMS SQL Injection Exploitation (CVE-2026-21643) in CrowdStrike LogScale
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
LogScale Detection Query
#event_simpleName=NetworkConnectIP4
| src_ip_address != "127.0.0.1"
| LocalPort in (443, 8013, 8014)
| join(
#event_simpleName=ProcessRollup2
| ImageFileName = "/FortiClient*" OR ImageFileName = "*EMS*" OR CommandLine = "*forticlient*"
| fields aid, ContextProcessId, CommandLine, ImageFileName
, field=[aid]
)
| #event_simpleName=DnsRequest
OR #event_simpleName=NetworkConnectIP4
| RemotePort in (1433, 3306, 5432)
| fields timestamp, aid, src_ip_address, LocalPort, RemotePort, ImageFileName, CommandLine
| eval sqli_context=if(match(CommandLine, "(?i)(sqlcmd|osql|xp_cmdshell|bcp |isql)"), "DB Command Execution", "Network Connection")
| stats count() as connection_count, values(sqli_context) as contexts by aid, src_ip_address, RemotePort
| where connection_count >= 1CrowdStrike CQL query correlating network connections to FortiClient EMS ports with subsequent database server connections and SQL command-line tool executions, indicating post-exploitation database access.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate database administration tools run by DBAs managing the EMS backend database
- Automated backup jobs connecting from EMS to SQL Server on standard ports
- Security tools performing authorized connectivity tests to FortiClient EMS
- Deployment scripts that interact with both EMS and SQL Server during maintenance windows
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
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