PH_Rule_SIGMA_2255
Enabled
Detects process LSASS memory dump using Mimikatz, NanoDump, Invoke-Mimikatz, Procdump or Taskmgr based on the CallTrace pointing to ntdll.dll, dbghelp.dll or dbgcore.dll for win10, server2016 and up. Mimikatz is a open source malware program that is commonly used by hackers and security professionals to extract sensitive information, such as passwords and credentials, from a system's memory. This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_access/proc_access_win_lsass_werfault.yml
7
Security
Credential Access
Credential Access consists of techniques for stealing credentials like account names and passwords. Techniques used to get credentials include keylogging or credential dumping. Using legitimate credentials can give adversaries access to systems, make them harder to detect, and provide the opportunity to create more accounts to help achieve their goals.
https://attack.mitre.org/tactics/TA0006T1003.001
OS Credential Dumping: LSASS Memory
Adversaries may attempt to access credential material stored in the process memory of the Local Security Authority Subsystem Service (LSASS).
https://attack.mitre.org/techniques/T1003/001Server
Windows Sysmon via FortiSIEM Agent
Correlation
Mimikatz is intended to be used by penetration testers and security red teams to simulate a real cyberthreat. Investigate whether the user needs to really run Mimikatz. Investigate what other incidents are occurring on that host during that time frame. 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-10-ProcessAccess" AND procName REGEXP "\\WerFault\.exe$" AND targetProcName REGEXP "\\lsass\.exe$" AND accessKeyId="0x1FFFFF"
This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID
accessKeyId,hostName,procName,targetProcName
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
accessKeyId = Filter.accessKeyId,
hostName = Filter.hostName,
procName = Filter.procName,
targetProcName = Filter.targetProcName