PH_Rule_SIGMA_1608
Enabled
Detects potential psexec command that initiate execution on a remote systems via common commandline flags used by the utility. This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_sysinternals_psexec_remote_execution.yml
7
Security
Resource Development
Resource Development consists of techniques that involve adversaries creating, purchasing, or compromising/stealing resources that can be used to support targeting. Such resources include infrastructure, accounts, or capabilities. These resources can be leveraged by the adversary to aid in other phases of the adversary lifecycle, such as using purchased domains to support Command and Control, email accounts for phishing as a part of Initial Access, or stealing code signing certificates to help with Defense Evasion.
https://attack.mitre.org/tactics/TA0042T1587.001
Develop Capabilities: Malware
Before compromising a victim, adversaries may develop malware and malware components that can be used during targeting. Building malicious software can include the development of payloads, droppers, post-compromise tools, backdoors, packers, C2 protocols, and the creation of infected removable media. Adversaries may develop malware to support their operations, creating a means for maintaining control of remote machines, evading defenses, and executing post-compromise behaviors.
https://attack.mitre.org/techniques/T1587/001Server
Windows Sysmon via FortiSIEM Agent
Correlation
Investigate whether the user needs to really run psexec.py on the specific host. Typically system administrators need these utilities to do their work. psexec.py 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-1-Create-Process" AND command REGEXP ".*accepteula.*" AND command REGEXP ".* -u .*" AND command REGEXP ".* -p .*" AND command REGEXP ".* \\\\.*"
This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID
command,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
command = Filter.command,
hostName = Filter.hostName