Suspicious Outbound SMTP Connections

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About the rule

Rule Type

Standard

Rule Description

Adversaries may steal data by exfiltrating it over an un-encrypted network protocol other than that of the existing command and control channel. The data may also be sent to an alternate network location from the main command and control server.

Severity

Trouble

Rule Requirement

Criteria

Action1: actionname = "sa_network_connection" AND (DEST_PORT = "25,587,465,2525" AND IS_INITIATED = "true") AND (PROCESSNAME notendswith "\thunderbird.exe,\outlook.exe" AND PROCESSNAME notstartswith "C:\Program Files\Microsoft\Exchange Server" AND (PROCESSNAME notstartswith "C:\Program Files\WindowsApps\microsoft.windowscommunicationsapps_" OR PROCESSNAME notendswith "\HxTsr.exe")) select Action1.HOSTNAME,Action1.MESSAGE,Action1.USERNAME,Action1.PROCESSNAME,Action1.DESTINATIONHOST,Action1.DESTINATION_IPV6,Action1.DEST_IP,Action1.SOURCEHOST,Action1.SOURCE_IP,Action1.SOURCE_IPV6

Detection

Execution Mode

realtime

Log Sources

Windows

Author

frack113