Windows Self Extraction Directive (.sed) File Created in Suspicious Paths

Alerts on .sed directive file creation under ProgramData/Temp/Tasks paths on Windows, consistent with iExpress-based packaging abuse.

FreeReviewedSigma · Medium · v2

Product: windows
Category: file_event
Author: Joseliyo Sanchez, @Joseliyo_Jstnk (SigmaHQ), DRL 1.1
Published: 2024-02-05
Updated: 2026-07-31

Analysis Detection

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1218System Binary Proxy Execution
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags creation events for self extraction directive files ending in .sed when the target filename is located under common attacker-preferred directories such as ProgramData, Temp, AppData Local Temp, and Windows Tasks folders. These .sed files can be consumed by iExpress (iexpress.exe) to build self-extracting packages, and their placement in sensitive or temporary paths can indicate staging or stealthy packaging. The detection relies on Windows file creation telemetry that includes the TargetFilename and supports substring and suffix matching.

Reporting behind it

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Windows Self Extraction Directive (.sed) File Created in Suspicious Paths

Pivot detection · T1218 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-detect-sed-directive-file-creation-in-suspicious-directories-760e75d8

title: Windows Self Extraction Directive (.sed) File Created in Suspicious Paths
id: 32cece5f-497c-44c6-afb4-026e456eacf3
related:
  - id: ab90dab8-c7da-4010-9193-563528cfa347
    type: derived
  - id: 760e75d8-c3b5-409b-a9bf-6130b4c4603f
    type: derived
status: test
description: This rule flags creation events for self extraction directive files ending in .sed when the target filename is located under common attacker-preferred directories such as ProgramData, Temp, AppData Local Temp, and Windows Tasks folders. These .sed files can be consumed by iExpress (iexpress.exe) to build self-extracting packages, and their placement in sensitive or temporary paths can indicate staging or stealthy packaging. The detection relies on Windows file creation telemetry that includes the TargetFilename and supports substring and suffix matching.
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
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/file/file_event/file_event_win_sed_file_creation.yml
author: Joseliyo Sanchez, @Joseliyo_Jstnk, Huntrule Team
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
license: DRL-1.1

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