Windows Debugger registry key for common Windows accessibility tools

Rule ID

PH_Rule_OSQ_WIN_3

Default Status

Enabled

Description

Detects the presence of the 'Debugger' registry key for common Windows accessibility tools. This Accessibility Tool Backdoor allows a user to assign a program of their choice (e.g. Notepad2.exe) to be the debugger to another program (e.g. Notepad.exe), so that the debugger program Notepad2.exe is automatically started when the program Notepad.exe is launched.

Severity

MITRE ATT&CK® Tactics

Privilege Escalation

Privilege Escalation consists of techniques that adversaries use to gain higher-level permissions on a system or network. Adversaries can often enter and explore a network with unprivileged access but require elevated permissions to follow through on their objectives. Common approaches are to take advantage of system weaknesses, misconfigurations, and vulnerabilities.

https://attack.mitre.org/tactics/TA0004

MITRE ATT&CK® Techniques

T1574.002

Hijack Execution Flow: DLL Side-Loading

Adversaries may execute their own malicious payloads by hijacking the library manifest used to load DLLs. Adversaries may take advantage of vague references in the library manifest of a program by replacing a legitimate library with a malicious one, causing the operating system to load their malicious library when it is called for by the victim program. Adversaries likely use this technique as a means of masking actions they perform under a legitimate, trusted system or software process.

https://attack.mitre.org/techniques/T1574/002

Impacts

Server

Data Source

Windows osquery windows_debugger_registry_keys 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 = "PH_OSQUERY_WIN_DEBUGGER_REGKEY" AND totalNum >= 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

reptDevName,regKeyPath,regValueName,newRegValue

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.reptDevName,
 regKeyPath = Filter.regKeyPath,
 regValueName = Filter.regValueName,
 newRegValue = Filter.newRegValue

FortiSIEM Rules