PH_Rule_SIGMA_1491
Enabled
Detects process creation with a renamed BrowserCore.exe (used to extract Azure tokens). a core component of Windows 10 and it serves as a browser add-on that allows Microsoft users to connect via Azure and Microsoft websites. This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_renamed_browsercore.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/TA0006T1528
Steal Application Access Token
Adversaries can steal user application access tokens as a means of acquiring credentials to access remote systems and resources. This can occur through social engineering and typically requires user action to grant access.
https://attack.mitre.org/techniques/T1528Server
Windows Sysmon via FortiSIEM Agent
Correlation
Determine if this was an authorized penetration testing activity or authorized sysadmin activity. 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-1-Create-Process" AND srcFileName="BrowserCore.exe" AND ((procName NOT REGEXP "\\BrowserCore\.exe$"))
This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID
hostName,procName,srcFileName
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
hostName = Filter.hostName,
procName = Filter.procName,
srcFileName = Filter.srcFileName