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Detection rules › Sigma

Suspicious HH.EXE Execution

Status
test
Severity
high
Log source
product windows, category process_creation
Author
Maxim Pavlunin
Source
github.com/SigmaHQ/sigma

Detects a suspicious execution of a Microsoft HTML Help (HH.exe)

MITRE ATT&CK coverage

TacticTechniques
Initial AccessT1566.001 Phishing: Spearphishing Attachment
ExecutionT1047 Windows Management Instrumentation, T1059.001 Command and Scripting Interpreter: PowerShell, T1059.003 Command and Scripting Interpreter: Windows Command Shell, T1059.005 Command and Scripting Interpreter: Visual Basic, T1059.007 Command and Scripting Interpreter: JavaScript
StealthT1218.001 System Binary Proxy Execution: Compiled HTML File, T1218.010 System Binary Proxy Execution: Regsvr32, T1218.011 System Binary Proxy Execution: Rundll32

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: Suspicious HH.EXE Execution
id: e8a95b5e-c891-46e2-b33a-93937d3abc31
status: test
description: Detects a suspicious execution of a Microsoft HTML Help (HH.exe)
references:
    - https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/chm-badness-delivers-a-banking-trojan/
    - https://github.com/elastic/protections-artifacts/commit/746086721fd385d9f5c6647cada1788db4aea95f#diff-27939090904026cc396b0b629c8e4314acd6f5dac40a676edbc87f4567b47eb7
    - https://www.ptsecurity.com/ww-en/analytics/pt-esc-threat-intelligence/higaisa-or-winnti-apt-41-backdoors-old-and-new/
    - https://www.zscaler.com/blogs/security-research/unintentional-leak-glimpse-attack-vectors-apt37
author: Maxim Pavlunin
date: 2020-04-01
modified: 2023-04-12
tags:
    - attack.execution
    - attack.initial-access
    - attack.stealth
    - attack.t1047
    - attack.t1059.001
    - attack.t1059.003
    - attack.t1059.005
    - attack.t1059.007
    - attack.t1218
    - attack.t1218.001
    - attack.t1218.010
    - attack.t1218.011
    - attack.t1566
    - attack.t1566.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - OriginalFileName: 'HH.exe'
        - Image|endswith: '\hh.exe'
    selection_paths:
        CommandLine|contains:
            - '.application'
            - '\AppData\Local\Temp\'
            - '\Content.Outlook\'
            - '\Downloads\'
            - '\Users\Public\'
            - '\Windows\Temp\'
            # - '\AppData\Local\Temp\Temp?_'
            # - '\AppData\Local\Temp\Rar$'
            # - '\AppData\Local\Temp\7z'
            # - '\AppData\Local\Temp\wz'
            # - '\AppData\Local\Temp\peazip-tmp'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_img

selection_img:
    - OriginalFileName: 'HH.exe'
    - Image|endswith: '\hh.exe'

Stage 2: selection_paths

selection_paths:
    CommandLine|contains:
        - '.application'
        - '\AppData\Local\Temp\'
        - '\Content.Outlook\'
        - '\Downloads\'
        - '\Users\Public\'
        - '\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
CommandLinematch
  • .application
  • \AppData\Local\Temp\ corpus 26 (sigma 26)
  • \Content.Outlook\
  • \Downloads\ corpus 14 (sigma 14)
  • \Users\Public\ corpus 17 (sigma 17)
  • \Windows\Temp\ corpus 12 (sigma 12)
Imageends_with
  • \hh.exe corpus 16 (sigma 16)
OriginalFileNameeq
  • HH.exe corpus 9 (sigma 5, splunk 4)