Detect SmarterMail Missing Authentication for Critical Function (CVE-2026-24423) in CrowdStrike LogScale
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
LogScale Detection Query
#event_simpleName=NetworkReceiveAccept OR #event_simpleName=NetworkConnectIP4
| UserName = "-" OR UserName = ""
| RemotePort IN (80, 443, 8080, 9998)
| CommandLine = /smartermail/i OR ImageFileName = /smartermail/i
| RemotePath IN ("/api/", "/admin/", "/settings/", "/interface/", "/services/")
| groupBy([SourceIP, RemoteIP, RemotePath, UserName], function=count(1, as=ConnectionCount))
| ConnectionCount > 2
| sort(ConnectionCount, order=desc)CrowdStrike Falcon LogScale CQL detecting network connections to SmarterMail process on administrative ports without associated authenticated user context, indicating potential unauthenticated access exploitation.
Data Sources
Required Tables
False Positives & Tuning
- SmarterMail service account processes that run as SYSTEM or non-domain accounts appearing without username attribution
- Automated backup or replication processes connecting to SmarterMail administrative ports with service identities
- Network scanning or security tools that connect to SmarterMail ports for inventory purposes
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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