Detection rules › Sigma

Legitimate Application Dropped Archive

Status
test
Severity
high
Log source
product windows, category file_event
Author
frack113, Florian Roth
Source
github.com/SigmaHQ/sigma

Detects programs on a Windows system that should not write an archive to disk

MITRE ATT&CK coverage

Event coverage

ProviderEventTitle
SysmonEvent ID 11FileCreate

Rule body yaml

title: Legitimate Application Dropped Archive
id: 654fcc6d-840d-4844-9b07-2c3300e54a26
status: test
description: Detects programs on a Windows system that should not write an archive to disk
references:
    - https://github.com/Neo23x0/sysmon-config/blob/3f808d9c022c507aae21a9346afba4a59dd533b9/sysmonconfig-export-block.xml#L1326
author: frack113, Florian Roth
date: 2022-08-21
tags:
    - attack.stealth
    - attack.t1218
logsource:
    product: windows
    category: file_event
detection:
    selection:
        Image|endswith:
            # Microsoft Office Programs Dropping Executables
            - \winword.exe
            - \excel.exe
            - \powerpnt.exe
            - \msaccess.exe
            - \mspub.exe
            - \eqnedt32.exe
            - \visio.exe
            - \wordpad.exe
            - \wordview.exe
            # LOLBINs that can be used to download executables
            - \certutil.exe
            - \certoc.exe
            - \CertReq.exe
            # - \bitsadmin.exe (depends on the environment; comment in if you're sure that bitsadmin doesn't do that in your env)
            - \Desktopimgdownldr.exe
            - \esentutl.exe
            # - \expand.exe
            - \finger.exe
            # Executables that should never drop an executable to disk (but may after a previous process injection or if it's malware that uses a legitimate name)
            - \notepad.exe
            - \AcroRd32.exe
            - \RdrCEF.exe
            - \mshta.exe
            - \hh.exe
        TargetFilename|endswith:
            - '.zip'
            - '.rar'
            - '.7z'
            - '.diagcab'
            - '.appx'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    Image|endswith:
        - \winword.exe
        - \excel.exe
        - \powerpnt.exe
        - \msaccess.exe
        - \mspub.exe
        - \eqnedt32.exe
        - \visio.exe
        - \wordpad.exe
        - \wordview.exe
        - \certutil.exe
        - \certoc.exe
        - \CertReq.exe
        - \Desktopimgdownldr.exe
        - \esentutl.exe
        - \finger.exe
        - \notepad.exe
        - \AcroRd32.exe
        - \RdrCEF.exe
        - \mshta.exe
        - \hh.exe
    TargetFilename|endswith:
        - '.zip'
        - '.rar'
        - '.7z'
        - '.diagcab'
        - '.appx'

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
Imageends_with
  • \AcroRd32.exe corpus 3 (sigma 3)
  • \CertReq.exe corpus 7 (sigma 7)
  • \Desktopimgdownldr.exe corpus 5 (sigma 5)
  • \RdrCEF.exe corpus 4 (sigma 4)
  • \certoc.exe corpus 10 (sigma 10)
  • \certutil.exe corpus 43 (sigma 43)
  • \eqnedt32.exe corpus 6 (sigma 6)
  • \esentutl.exe corpus 8 (sigma 8)
  • \excel.exe corpus 18 (sigma 18)
  • \finger.exe corpus 8 (sigma 8)
  • \hh.exe corpus 16 (sigma 16)
  • \msaccess.exe corpus 4 (sigma 4)
  • \mshta.exe corpus 67 (sigma 67)
  • \mspub.exe corpus 10 (sigma 10)
  • \notepad.exe corpus 9 (sigma 9)
  • \powerpnt.exe corpus 15 (sigma 15)
  • \visio.exe corpus 3 (sigma 3)
  • \winword.exe corpus 20 (sigma 20)
  • \wordpad.exe corpus 5 (sigma 5)
  • \wordview.exe corpus 6 (sigma 6)
TargetFilenameends_with
  • .7z corpus 5 (sigma 5)
  • .appx
  • .diagcab corpus 2 (sigma 2)
  • .rar corpus 5 (sigma 5)
  • .zip corpus 7 (sigma 6, splunk 1)