FortiSIEM Rules

Failed Account Activity On Prior Disabled Account

Rule ID

PH_Rule_Access_60

Default Status

Enabled

Description

Detects failed account activity to a recently disabled account

Severity

8

Category

Security

MITRE ATT&CK® Tactics

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/TA0006

MITRE ATT&CK® Techniques


T1110.001

Brute Force: Password Guessing

Adversaries with no prior knowledge of legitimate credentials within the system or environment may guess passwords to attempt access to accounts.

https://attack.mitre.org/techniques/T1110/001

Impacts

Server

Data Source

Windows Security 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.

86400 seconds

Trigger Conditions

If the following defined pattern/s occur within a 86400 second time window.

AcctDisabled FOLLOWED_BY FailedLogin

Global Constraint

This defines how two or more distinct events are related in a time-series based action. e.g. An event occurs followed by another event if the source IP, user, and messageId are the same

AcctDisabled.reptDevIpAddr = FailedLogin.reptDevIpAddr AND AcctDisabled.targetUser = FailedLogin.user

SubPattern Definitions

SubPattern Name: AcctDisabled

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 IN ("Win-Security-629","Win-Security-4725")

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

reptDevName,reptDevIpAddr,targetUser,computer

Aggregate Constraint

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

COUNT (*) >= 1
Operator Rank: 0 Operator Type: FOLLOWED_BY

This operator defines the logic condition relating to the prior event subpattern clause and the following event subpattern clause

SubPattern Name: FailedLogin

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 IN (Group@PH_SYS_EVENT_HostLogonFailure,Group@PH_SYS_EVENT_DomainLogonFailure)

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

reptDevIpAddr,user,computer

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

 destName = AcctDisabled.reptDevName,
 destIpAddr = AcctDisabled.reptDevIpAddr,
 user = AcctDisabled.targetUser,
 computer = FailedLogin.computer