Self Extracting Package Creation Via Iexpress.EXE From Potentially Suspicious Location — Sigma Rule

Rule metadata and linked tags

Author: Joseliyo Sanchez, @Joseliyo_Jstnk, Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2024-02-05 / 2024-06-04.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 5319410ec73a2f15e7702d6591ec5334a42775badd9679d7edb056ebacd4440a

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Self Extracting Package Creation Via Iexpress.EXE From Potentially Suspicious Location
id: b2b048b0-7857-4380-b0fb-d3f0ab820b71
status: test
description: |
    Detects the use of iexpress.exe to create binaries via Self Extraction Directive (SED) files located in potentially suspicious locations.
    This behavior has been observed in-the-wild by different threat actors.
references:
    - https://strontic.github.io/xcyclopedia/library/iexpress.exe-D594B2A33EFAFD0EABF09E3FDC05FCEA.html
    - https://en.wikipedia.org/wiki/IExpress
    - https://decoded.avast.io/janvojtesek/raspberry-robins-roshtyak-a-little-lesson-in-trickery/
    - https://www.virustotal.com/gui/file/602f4ae507fa8de57ada079adff25a6c2a899bd25cd092d0af7e62cdb619c93c/behavior
author: Joseliyo Sanchez, @Joseliyo_Jstnk, Nasreddine Bencherchali (Nextron Systems)
date: 2024-02-05
modified: 2024-06-04
tags:
    - attack.stealth
    - attack.t1218
logsource:
    category: process_creation
    product: windows
detection:
    # VT Query: behavior_processes:"iexpress.exe" and behavior_processes:"/n /q /m" and behavior_processes:"*.sed*" and p:5+
    selection_img:
        - Image|endswith: '\iexpress.exe'
        - OriginalFileName: 'IEXPRESS.exe'
    selection_cli:
        CommandLine|contains|windash: ' /n '
    selection_paths:
        CommandLine|contains:
            # Note: Add more uncommon paths that fit your organizational needs.
            - ':\ProgramData\'
            - ':\Temp\'
            - ':\Windows\System32\Tasks\'
            - ':\Windows\Tasks\'
            - ':\Windows\Temp\'
            - '\AppData\Local\Temp\'
    condition: all of selection_*
falsepositives:
    - Administrators building packages using iexpress.exe
level: high

Original YAML and metadata in JSON

False positives

• Administrators building packages using iexpress.exe

Source references

• https://strontic.github.io/xcyclopedia/library/iexpress.exe-D594B2A33EFAFD0EABF09E3FDC05FCEA.html
• https://en.wikipedia.org/wiki/IExpress
• https://decoded.avast.io/janvojtesek/raspberry-robins-roshtyak-a-little-lesson-in-trickery/
• https://www.virustotal.com/gui/file/602f4ae507fa8de57ada079adff25a6c2a899bd25cd092d0af7e62cdb619c93c/behavior