PH_Rule_SIGMA_1084
Enabled
Detects process access to LSASS memory with suspicious access flags. Local Security Authority Subsystem Service (LSASS.exe) manages system-level authentication. This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_access/proc_access_win_susp_proc_access_lsass.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
Determine if this was an authorized penetration testing activity on the host. Otherwise, there is no reason for this activity to be occurring. The host should be quarantined and investigated immediately. Collect the process hash and check for malware match. Investigate what other incidents are occurring on that host during that time frame.
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 (targetProcName REGEXP "\\lsass\.exe$" AND accessKeyId REGEXP "0x14C2$|18$|1A$|30$|38$|3A$|50$|58$|5A$|70$|78$|7A$|90$|98$|9A$|B0$|B8$|BA$|D0$|D8$|DA$|F0$|F8$|FA$") AND ((( procName NOT IN ("C:\\PROGRAMDATA\\MALWAREBYTES\\MBAMSERVICE\\ctlrupdate\\mbupdatr.exe","C:\\Program Files (x86)\\Cisco\\Cisco AnyConnect Secure Mobility Client\\vpnagent.exe","C:\\Program Files\\Cisco\\Cisco AnyConnect Secure Mobility Client\\vpnagent.exe","C:\\Program Files\\Malwarebytes\\Anti-Malware\\MBAMService.exe","C:\\Program Files\\Windows Defender\\MsMpEng.exe","C:\\WINDOWS\\System32\\perfmon.exe","C:\\WINDOWS\\system32\\taskhostw.exe","C:\\WINDOWS\\system32\\taskmgr.exe","C:\\Windows\\SysWOW64\\msiexec.exe","C:\\Windows\\System32\\MRT.exe","C:\\Windows\\System32\\lsass.exe","C:\\Windows\\System32\\msiexec.exe") AND procName NOT REGEXP "^C:\\Users\\.*\\AppData\\Local\\Programs\\Microsoft VS Code\\Code\.exe$" )) AND (procName NOT REGEXP "^C:\\ProgramData\\Microsoft\\Windows Defender\\" OR procName NOT REGEXP "\\MsMpEng\.exe$") AND (procPath NOT REGEXP ".*\|C:\\ProgramData\\Microsoft\\Windows Defender\\Definition Updates\\\{.*" OR procPath NOT REGEXP ".*\}\\mpengine\.dll\+.*" OR accessKeyId!="0x1418") AND (procName!="C:\\Program Files\\Microsoft Security Client\\MsMpEng.exe" OR accessKeyId!="0x1418") AND (procName NOT REGEXP "^C:\\ProgramData\\VMware\\VMware Tools\\" OR procName NOT REGEXP "\\vmtoolsd\.exe$") AND (procName NOT REGEXP "^C:\\Program Files \(x86\)\\|^C:\\Program Files\\" OR procName NOT REGEXP ".*Antivirus.*") AND (procName!="C:\\WINDOWS\\system32\\MRT.exe" OR accessKeyId!="0x1418") AND (procName!="C:\\Program Files\\Common Files\\McAfee\\MMSSHost\\MMSSHOST.exe") AND (procName NOT REGEXP "^C:\\Windows\\Temp\\asgard2-agent\\" OR procName NOT REGEXP "\\thor64\.exe$|\\thor\.exe$" OR 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,procPath,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,
procPath = Filter.procPath,
targetProcName = Filter.targetProcName