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Detection rules › Sigma

Suspicious Application Allowed Through Exploit Guard

Status
test
Severity
high
Log source
product windows, category registry_set
Author
Nasreddine Bencherchali (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects applications being added to the "allowed applications" list of exploit guard in order to bypass controlled folder settings

MITRE ATT&CK coverage

TacticTechniques
Defense ImpairmentT1685 Disable or Modify Tools

Event coverage

ProviderEventTitle
SysmonEvent ID 13RegistryEvent (Value Set)

Rule body yaml

title: Suspicious Application Allowed Through Exploit Guard
id: 42205c73-75c8-4a63-9db1-e3782e06fda0
status: test
description: Detects applications being added to the "allowed applications" list of exploit guard in order to bypass controlled folder settings
references:
    - https://www.microsoft.com/security/blog/2017/10/23/windows-defender-exploit-guard-reduce-the-attack-surface-against-next-generation-malware/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-08-05
modified: 2023-08-17
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    category: registry_set
    product: windows
detection:
    selection_key:
        TargetObject|contains: 'SOFTWARE\Microsoft\Windows Defender\Windows Defender Exploit Guard\Controlled Folder Access\AllowedApplications'
    selection_paths:
        TargetObject|contains:
            # Add more paths you don't allow in your org
            - '\Users\Public\'
            - '\AppData\Local\Temp\'
            - '\Desktop\'
            - '\PerfLogs\'
            - '\Windows\Temp\'
    condition: all of selection_*
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_key

selection_key:
    TargetObject|contains: 'SOFTWARE\Microsoft\Windows Defender\Windows Defender Exploit Guard\Controlled Folder Access\AllowedApplications'

Stage 2: selection_paths

selection_paths:
    TargetObject|contains:
        - '\Users\Public\'
        - '\AppData\Local\Temp\'
        - '\Desktop\'
        - '\PerfLogs\'
        - '\Windows\Temp\'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
TargetObjectmatch
  • SOFTWARE\Microsoft\Windows Defender\Windows Defender Exploit Guard\Controlled Folder Access\AllowedApplications
  • \AppData\Local\Temp\
  • \Desktop\
  • \PerfLogs\
  • \Users\Public\
  • \Windows\Temp\