Detect SmarterMail Unrestricted File Upload Exploitation (CVE-2025-52691) in CrowdStrike LogScale
Detects exploitation of CVE-2025-52691, an unrestricted file upload vulnerability in SmarterTools SmarterMail. This vulnerability allows attackers to upload files with dangerous types (e.g., web shells, executables) to the mail server, potentially enabling remote code execution. This CVE is listed in CISA's Known Exploited Vulnerabilities catalog.
MITRE ATT&CK
- Tactic
- Initial Access Execution Persistence
LogScale Detection Query
event_simpleName IN ("FileCreate", "ProcessRollup2")
| eval lower_path=lower(TargetFileName), lower_image=lower(ImageFileName), lower_parent=lower(ParentBaseFileName)
| where (
(event_simpleName="FileCreate"
AND (lower_path LIKE "%smartermail%" OR lower_path LIKE "%mailroot%" OR lower_path LIKE "%webmail%")
AND match(lower_path, @"\.(aspx|asp|php|jsp|cfm|cgi|pl|exe|dll|bat|cmd|ps1|vbs|hta)$"))
OR
(event_simpleName="ProcessRollup2"
AND lower_parent LIKE "%smartermail.exe%"
AND (lower_image LIKE "%cmd.exe%" OR lower_image LIKE "%powershell.exe%" OR lower_image LIKE "%wscript.exe%"
OR lower_image LIKE "%cscript.exe%" OR lower_image LIKE "%mshta.exe%" OR lower_image LIKE "%certutil.exe%"))
)
| table _time, ComputerName, UserName, event_simpleName, TargetFileName, ImageFileName, ParentBaseFileName, CommandLine
| sort -_timeCrowdStrike Falcon Query Language detection for file creation with dangerous extensions in SmarterMail directories and suspicious child process execution from SmarterMail parent, indicating active exploitation of CVE-2025-52691.
Data Sources
Required Tables
False Positives & Tuning
- CrowdStrike sensor or other security agent processes spawning from SmarterMail service context
- Legitimate automated deployment pipelines writing configuration files with unusual extensions to mail server paths
- SmarterMail licensed add-ons or third-party integrations that create executable content in the application directory
Other platforms for CVE-2025-52691
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 1Simulate Web Shell Upload to SmarterMail Directory
Expected signal: Sysmon Event ID 11 (FileCreate) with TargetFilename containing 'SmarterMail' and ending in '.aspx'; DeviceFileEvents in Defender with ActionType=FileCreated
- Test 2Simulate SmarterMail Spawning Suspicious Child Process
Expected signal: Sysmon Event ID 1 (ProcessCreate) showing cmd.exe with parent process context; DeviceProcessEvents showing cmd.exe creation with CommandLine containing 'whoami'
- Test 3Upload Executable File to Simulated Mail Server Web Directory
Expected signal: Sysmon Event ID 11 (FileCreate) with TargetFilename matching 'C:\Temp\mailroot\webmail\update.exe'; file hash telemetry for the copied executable
- Test 4Simulate PowerShell Execution via Web Shell Context
Expected signal: Sysmon Event ID 1 (ProcessCreate) for powershell.exe with CommandLine containing reconnaissance commands; PowerShell Script Block Logging (Event ID 4104) if enabled
Unlock Pro Content
Get the full detection package for CVE-2025-52691 including response playbook, investigation guide, and atomic red team tests.