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Detection rules › Sigma

Self Extraction Directive File Created In Potentially Suspicious Location

Status
test
Severity
medium
Log source
product windows, category file_event
Author
Joseliyo Sanchez, @Joseliyo_Jstnk
Source
github.com/SigmaHQ/sigma

Detects the creation of Self Extraction Directive files (.sed) in a potentially suspicious location. These files are used by the "iexpress.exe" utility in order to create self extracting packages. Attackers were seen abusing this utility and creating PE files with embedded ".sed" entries.

MITRE ATT&CK coverage

TacticTechniques
StealthT1218 System Binary Proxy Execution

Event coverage

ProviderEventTitle
SysmonEvent ID 11FileCreate

Rule body yaml

title: Self Extraction Directive File Created In Potentially Suspicious Location
id: 760e75d8-c3b5-409b-a9bf-6130b4c4603f
related:
    - id: ab90dab8-c7da-4010-9193-563528cfa347
      type: derived
status: test
description: |
    Detects the creation of Self Extraction Directive files (.sed) in a potentially suspicious location.
    These files are used by the "iexpress.exe" utility in order to create self extracting packages.
    Attackers were seen abusing this utility and creating PE files with embedded ".sed" entries.
references:
    - https://strontic.github.io/xcyclopedia/library/iexpress.exe-D594B2A33EFAFD0EABF09E3FDC05FCEA.html
    - https://en.wikipedia.org/wiki/IExpress
    - https://www.virustotal.com/gui/file/602f4ae507fa8de57ada079adff25a6c2a899bd25cd092d0af7e62cdb619c93c/behavior
author: Joseliyo Sanchez, @Joseliyo_Jstnk
date: 2024-02-05
tags:
    - attack.stealth
    - attack.t1218
logsource:
    category: file_event
    product: windows
detection:
    selection:
        TargetFilename|contains:
            - ':\ProgramData\'
            - ':\Temp\'
            - ':\Windows\System32\Tasks\'
            - ':\Windows\Tasks\'
            - ':\Windows\Temp\'
            - '\AppData\Local\Temp\'
        TargetFilename|endswith: '.sed'
    condition: selection
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    TargetFilename|contains:
        - ':\ProgramData\'
        - ':\Temp\'
        - ':\Windows\System32\Tasks\'
        - ':\Windows\Tasks\'
        - ':\Windows\Temp\'
        - '\AppData\Local\Temp\'
    TargetFilename|endswith: '.sed'

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
TargetFilenameends_with
  • .sed corpus 2 (sigma 2)
TargetFilenamematch
  • :\ProgramData\ corpus 4 (sigma 4)
  • :\Temp\ corpus 5 (sigma 5)
  • :\Windows\System32\Tasks\ corpus 2 (sigma 2)
  • :\Windows\Tasks\ corpus 2 (sigma 2)
  • :\Windows\Temp\ corpus 2 (sigma 2)
  • \AppData\Local\Temp\ corpus 8 (sigma 8)