Windows: LPE InstallerFileTakeOver PoC CVE-2021-41379

Rule ID

PH_Rule_SIGMA_1793

Default Status

Enabled

Description

Detects PoC tool used to exploit LPE vulnerability CVE-2021-41379. This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/builtin/application/msiinstaller/win_vul_cve_2021_41379.yml

Severity

MITRE ATT&CK® Tactics

Initial Access

Initial Access consists of techniques that use various entry vectors to gain their initial foothold within a network. Techniques used to gain a foothold include targeted spearphishing and exploiting weaknesses on public-facing web servers. Footholds gained through initial access may allow for continued access, like valid accounts and use of external remote services, or may be limited-use due to changing passwords.

https://attack.mitre.org/tactics/TA0001

MITRE ATT&CK® Techniques

T1190

Exploit Public-Facing Application

Adversaries may attempt to take advantage of a weakness in an Internet-facing computer or program using software, data, or commands in order to cause unintended or unanticipated behavior. The weakness in the system can be a bug, a glitch, or a design vulnerability. These applications are often websites, but can include databases, standard services, and any other applications with Internet accessible open sockets, such as web servers and related services. Depending on the flaw being exploited this may include Exploitation for Defense Evasion.

https://attack.mitre.org/techniques/T1190

Impacts

Server

Data Source

Windows Application Log Via OMI or 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-App-MsiInstaller-1033" AND lineContent REGEXP ".*test pkg.*"

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

hostName,lineContent

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

hostName = Filter.hostName,
lineContent = Filter.lineContent

FortiSIEM Rules