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Detection rules › Sigma

Potential Suspicious Execution From GUID Like Folder Names

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

Detects potential suspicious execution of a GUID like folder name located in a suspicious location such as %TEMP% as seen being used in IcedID attacks. Use this rule to hunt for potentially suspicious activity stemming from uncommon folders.

MITRE ATT&CK coverage

TacticTechniques
StealthT1027 Obfuscated Files or Information

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation
Security-AuditingEvent ID 4688A new process has been created.

Rule body yaml

title: Potential Suspicious Execution From GUID Like Folder Names
id: 90b63c33-2b97-4631-a011-ceb0f47b77c3
status: test
description: |
    Detects potential suspicious execution of a GUID like folder name located in a suspicious location such as %TEMP% as seen being used in IcedID attacks.
    Use this rule to hunt for potentially suspicious activity stemming from uncommon folders.
references:
    - https://twitter.com/Kostastsale/status/1565257924204986369
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-09-01
modified: 2023-03-02
tags:
    - attack.stealth
    - attack.t1027
    - detection.threat-hunting
logsource:
    category: process_creation
    product: windows
detection:
    # Uncomment this section and remove the filter if you want the rule to be more specific to processes
    # selection_img:
    #     Image|endswith:
    #         - '\rundll32.exe'
    selection_folder:
        CommandLine|contains:
            # Add more suspicious or unexpected paths
            - '\AppData\Roaming\'
            - '\AppData\Local\Temp\' # This could generate some FP with some installers creating folders with GUID
    selection_guid:
        CommandLine|contains|all:
            - '\{'
            - '}\'
    filter_main_image_guid:
        Image|contains|all:
            - '\{'
            - '}\'
    filter_main_null:
        Image: null
    filter_main_driver_inst:  # DrvInst.exe "4" "0" "C:\Users\venom\AppData\Local\Temp\{a0753cc2-fcea-4d49-a787-2290b564b06f}\nvvhci.inf" "9" "43a2fa8e7" "00000000000001C0" "WinSta0\Default" "00000000000001C4" "208" "c:\program files\nvidia corporation\installer2\nvvhci.{eb7b4460-7ec9-42d6-b73f-d487d4550526}"
        Image: 'C:\Windows\System32\drvinst.exe'
    filter_main_msiexec:
        Image:
            - 'C:\Windows\System32\msiexec.exe'
            - 'C:\Windows\SysWOW64\msiexec.exe'
    condition: all of selection_* and not 1 of filter*
falsepositives:
    - Installers are sometimes known for creating temporary folders with GUID like names. Add appropriate filters accordingly
level: low

Stages and Predicates

Stage 0: condition

all of selection_* and not 1 of filter*

Stage 1: selection_folder

selection_folder:
    CommandLine|contains:
        - '\AppData\Roaming\'
        - '\AppData\Local\Temp\'

Stage 2: selection_guid

selection_guid:
    CommandLine|contains|all:
        - '\{'
        - '}\'

Stage 3: not filter*

filter_main_image_guid:
    Image|contains|all:
        - '\{'
        - '}\'
filter_main_null:
    Image: null
filter_main_driver_inst:
    Image: 'C:\Windows\System32\drvinst.exe'
filter_main_msiexec:
    Image:
        - 'C:\Windows\System32\msiexec.exe'
        - 'C:\Windows\SysWOW64\msiexec.exe'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
Imagematch\{
Imagematch}\
ImageeqC:\Windows\SysWOW64\msiexec.exe
ImageeqC:\Windows\System32\drvinst.exe
ImageeqC:\Windows\System32\msiexec.exe
Imageis_null(no value, null check)

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
CommandLinematch
  • \AppData\Local\Temp\ corpus 26 (sigma 26)
  • \AppData\Roaming\ corpus 16 (sigma 16)
  • \{
  • }\