Windows: Code Integrity Attempted DLL Load

Rule ID

PH_Rule_SIGMA_1816

Default Status

Enabled

Description

Detects attempted DLL load events that didn't meet anti-malware or Windows signing level requirements. It often means the file's signature is revoked or expired. This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/builtin/code_integrity/win_codeintegrity_attempted_dll_load.yml

Severity

MITRE ATT&CK® Tactics

Persistence

Persistence consists of techniques that adversaries use to keep access to systems across restarts, changed credentials, and other interruptions that could cut off their access. Techniques used for persistence include any access, action, or configuration changes that let them maintain their foothold on systems, such as replacing or hijacking legitimate code or adding startup code.

https://attack.mitre.org/tactics/TA0003

MITRE ATT&CK® Techniques

No Technique Specified

Impacts

Server

Data Source

Windows Code Integrity/Operational logs via FortiSIEM Agent

Detection

Correlation

Remediation Guidance

No remediation guidance specified

Time Window

If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.

300 seconds

Trigger Conditions

If the following defined pattern/s occur within a 300 second time window.

Filter

SubPattern Definitions

SubPattern Name: Filter

This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.

SubPattern Query

This is the query logic that matches incoming events

eventType = "Win-CodeIntegrity-Operational-3033" AND ((fileName NOT REGEXP "\\Program Files\\DTrace\\dtrace\.dll$" OR procName NOT REGEXP "\\Windows\\System32\\svchost\.exe$" OR policyIdentity!="12" OR recipientPolicyId!="1") AND (fileName NOT REGEXP ".*\\Windows\\System32\\DriverStore\\FileRepository\\.*" OR fileName NOT REGEXP "\\igd10iumd64\.dll$" OR policyIdentity!="7" OR recipientPolicyId!="1") AND (fileName NOT REGEXP "\\Windows\\System32\\nvspcap64\.dll$" OR procName NOT REGEXP "\\AppData\\Local\\Keybase\\Gui\\Keybase\.exe$|\\Microsoft\\Teams\\stage\\Teams\.exe$" OR policyIdentity!="8" OR recipientPolicyId!="1") AND (fileName NOT REGEXP "\\Program Files\\Bonjour\\mdnsNSP\.dll$" OR procName NOT REGEXP "\\Windows\\System32\\SIHClient\.exe$|\\Windows\\System32\\svchost\.exe$" OR policyIdentity NOT IN ("12","8") OR recipientPolicyId!="1") AND (fileName NOT REGEXP ".*\\Microsoft Office\\root\\vfs\\ProgramFilesCommonX64\\Microsoft Shared\\OFFICE.*" OR fileName NOT REGEXP "\\MSOXMLMF\.DLL$" OR policyIdentity!="7" OR recipientPolicyId!="1") AND (fileName NOT REGEXP "\\Windows\\System32\\nvspcap64\.dll$" OR procName NOT REGEXP ".*\\AppData\\Local\\slack\\app-.*" OR procName NOT REGEXP "\\slack\.exe$" OR policyIdentity!="8" OR recipientPolicyId!="1") AND (fileName NOT REGEXP "\\Mozilla Firefox\\mozavcodec\.dll$|\\Mozilla Firefox\\mozavutil\.dll$" OR procName NOT REGEXP "\\Mozilla Firefox\\firefox\.exe$" OR policyIdentity!="8") AND (fileName NOT REGEXP "\\Program Files \(x86\)\\Avast Software\\Avast\\aswAMSI\.dll$|\\Program Files\\Avast Software\\Avast\\aswAMSI\.dll$" OR policyIdentity NOT IN ("12","8") OR recipientPolicyId!="1") AND (fileName NOT REGEXP ".*\\Windows\\assembly\\GAC\\.*" OR procName NOT REGEXP "\\mscorsvw\.exe$" OR procName NOT REGEXP ".*\\Windows\\Microsoft\.NET\\.*" OR policyIdentity!="8" OR recipientPolicyId NOT IN ("1","2")) AND (fileName NOT REGEXP ".*\\Program Files\\Google\\Drive File Stream\\.*" OR fileName NOT REGEXP "\\crashpad_handler\.exe$" OR procName NOT REGEXP "\\Windows\\ImmersiveControlPanel\\SystemSettings\.exe$" OR policyIdentity!="8" OR recipientPolicyId!="1"))

Group by Attributes

This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID

fileName,hostName,policyIdentity,procName,recipientPolicyId

Aggregate Constraint

This is most typically a numerical constraint that defines when the rule should trigger an incident

COUNT(*) >= 1

Incident Attribute Mapping

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

fileName = Filter.fileName,
hostName = Filter.hostName,
policyIdentity = Filter.policyIdentity,
procName = Filter.procName,
recipientPolicyId = Filter.recipientPolicyId

FortiSIEM Rules