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
Unlock Pro Content
Get the full detection package for CVE-2026-21643 including response playbook, investigation guide, and atomic red team tests.