PH_Rule_SIGMA_1205
Enabled
Look for non-system accounts SMB accessing a file with write (0x2) access mask via administrative share (i.e C$). This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/builtin/security/win_security_smb_file_creation_admin_shares.yml
7
Security
Lateral Movement
Lateral Movement consists of techniques that adversaries use to enter and control remote systems on a network. Following through on their primary objective often requires exploring the network to find their target and subsequently gaining access to it. Reaching their objective often involves pivoting through multiple systems and accounts to gain. Adversaries might install their own remote access tools to accomplish Lateral Movement or use legitimate credentials with native network and operating system tools, which may be stealthier.
https://attack.mitre.org/tactics/TA0008T1021.002
Remote Services: SMB/Windows Admin Shares
Adversaries may use Valid Accounts to interact with a remote network share using Server Message Block (SMB). The adversary may then perform actions as the logged-on user.
https://attack.mitre.org/techniques/T1021/002Server
Windows Security Log via OMI or FortiSIEM Agent
Correlation
No remediation guidance specified
If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.
300 seconds
If the following defined pattern/s occur within a 300 second time window.
Filter
This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.
This is the query logic that matches incoming events
(eventType="Win-Security-5145" AND fileName REGEXP "C\$$" AND fileAccess="0x2") AND (user NOT REGEXP "\$$")
This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID
fileAccess,fileName,hostName,user
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
fileAccess = Filter.fileAccess,
fileName = Filter.fileName,
hostName = Filter.hostName,
user = Filter.user