PH_Rule_SIGMA_2000
Enabled
Detects creation of the PSEXEC key file, which is created anytime a PsExec command is executed. It gets written to the file system and will be recorded in the USN Journal on the target system. This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/file/file_event/file_event_win_sysinternals_psexec_service_key.yml
7
Security
Lateral Movement
Lateral Movement consists of techniques that adversaries use to enter and control remote systems on a network. Following through on their primary objective often requires exploring the network to find their target and subsequently gaining access to it. Reaching their objective often involves pivoting through multiple systems and accounts to gain. Adversaries might install their own remote access tools to accomplish Lateral Movement or use legitimate credentials with native network and operating system tools, which may be stealthier.
https://attack.mitre.org/tactics/TA0008T1570
Lateral Tool Transfer
Adversaries may transfer tools or other files between systems in a compromised environment. Files may be copied from one system to another to stage adversary tools or other files over the course of an operation. Adversaries may copy files laterally between internal victim systems to support lateral movement using inherent file sharing protocols such as file sharing over SMB to connected network shares or with authenticated connections with SMB/Windows Admin Shares.
https://attack.mitre.org/techniques/T1570Server
Windows Sysmon via FortiSIEM Agent
Correlation
Investigate whether the user needs to really run PAExec or PsExec. Typically system administrators need these utilities to do their work. PAExec may be bundled with other software. If necessary, rebuild the host from a known, good source and have the user change their password.
If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.
300 seconds
If the following defined pattern/s occur within a 300 second time window.
Filter
This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.
This is the query logic that matches incoming events
eventType="Win-Sysmon-11-FileCreate" AND fileName REGEXP "^C:\\Windows\\PSEXEC-" AND fileName REGEXP "\.key$"
This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID
fileName,hostName
This is most typically a numerical constraint that defines when the rule should trigger an incident
COUNT(*) >= 1
This section defines which fields in matching raw events should be mapped to the incident attributes in the resulting incident.
The available raw event attributes to map are limited to the group by attributes and the aggregate event constraint fields for each subpattern
fileName = Filter.fileName,
hostName = Filter.hostName