Detect SmarterMail Missing Authentication for Critical Function (CVE-2026-24423) in IBM QRadar
Detects exploitation of CVE-2026-24423, a missing authentication vulnerability (CWE-306) in SmarterTools SmarterMail. This KEV-listed vulnerability allows unauthenticated attackers to access critical functions in SmarterMail, potentially enabling unauthorized administrative access, data exfiltration, or further lateral movement. Detection focuses on unauthenticated access patterns to administrative and critical API endpoints.
MITRE ATT&CK
QRadar Detection Query
SELECT
sourceip,
destinationip,
URL,
username,
"HTTP Method" as http_method,
"HTTP Response Code" as response_code,
starttime,
COUNT(*) as request_count
FROM events
WHERE LOGSOURCETYPENAME(devicetype) ILIKE '%IIS%'
AND (URL ILIKE '%/api/%' OR URL ILIKE '%/admin/%' OR URL ILIKE '%/settings/%' OR URL ILIKE '%/interface/%')
AND "HTTP Method" IN ('POST', 'PUT', 'DELETE', 'PATCH')
AND (username IS NULL OR username = '-' OR username = '')
AND "HTTP Response Code" IN (200, 201, 204, 302)
AND LOGSOURCENAME(logsourceid) ILIKE '%SmarterMail%'
GROUP BY sourceip, destinationip, URL, username, http_method, response_code, starttime
HAVING COUNT(*) > 1
LAST 60 MINUTESQRadar AQL query detecting unauthenticated successful HTTP requests to SmarterMail critical function endpoints, grouped by source IP and URL to surface exploitation patterns.
Data Sources
Required Tables
False Positives & Tuning
- Automated integration services that authenticate via custom mechanisms not visible in standard IIS logs
- Internal administrative tools accessing SmarterMail API endpoints with service account tokens logged elsewhere
- QRadar log source misconfiguration where username field mapping is incorrect for SmarterMail IIS logs
Other platforms for CVE-2026-24423
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 1Unauthenticated GET to SmarterMail Admin API Endpoint
Expected signal: IIS access log entry with csUsername='-', cs-method=GET, sc-status=200, cs-uri-stem=/api/v1/settings/sysadmin/general
- Test 2Unauthenticated POST to SmarterMail User Creation Endpoint
Expected signal: IIS log: csMethod=POST, csUriStem=/api/v1/settings/sysadmin/users, csUsername=-, scStatus=200 or 201. SmarterMail app log: new user creation event for [email protected]
- Test 3Unauthenticated SmarterMail Mail Forwarding Rule Injection
Expected signal: IIS log entry: POST to /api/v1/settings/sysadmin/users/[email protected]/forwardingRules with csUsername='-' and scStatus=200. SmarterMail audit log: forwarding rule added for [email protected] pointing to external domain.
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