Windows: Suspicious Cabinet (CAB) File Expansion via expand.exe from Uncommon Paths

Flags expand.exe ("-F:") extracting cabinets when used from suspicious/uncommon Windows paths.

FreeReviewedSigma · Medium · v2

Product: windows
Category: process_creation
Author: Bhabesh Raj, X__Junior (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2021-07-30
Updated: 2026-07-31

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 Windows executions of expand.exe with the -F argument that expand CAB files originating from potentially suspicious or uncommon directories (e.g., Perflogs, ProgramData, Public, Windows Temp, Admin$ shares, Temp under AppData). Attackers may use this behavior to extract embedded payloads or staging files while blending into normal-looking system activity. It relies on process creation telemetry capturing Image and CommandLine, including parent process context.

Reporting behind it

Related detections9 linkedT1218 — drag to rearrange

Suspicious Renamed Windows Debugger CDB Execution

Suspicious Scripting Interpreter Execution From Downloads Or Temp via Reputation Hijacking

Suspicious MMC Console Spawning Script Interpreter via GrimResource

Suspicious MMC Console Loading MSC File From User Writable Path

Suspicious Cabinet Extraction of Masqueraded vstm Archive via extrac32

Malicious DLL Execution via Wuauclt Update Handler (via process_creation)

Malicious aspnet_compiler.exe Injection Host Spawned by PowerShell via process_creation

Malicious regsvcs LOLBin Loading Ransomware DLL from UNC Path

Suspicious RegAsm or RegSvcs Spawned by Script Host (via process_creation)

Windows: Suspicious Cabinet (CAB) File Expansion via expand.exe from Uncommon 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-alert-on-expand-exe-cabinet-file-expansion-from-uncommon-paths-9f107a84

title: "Windows: Suspicious Cabinet (CAB) File Expansion via expand.exe from Uncommon Paths"
id: 4c525ce6-793c-476a-84b0-fe3cd42cf064
status: test
description: This rule flags Windows executions of expand.exe with the -F argument that expand CAB files originating from potentially suspicious or uncommon directories (e.g., Perflogs, ProgramData, Public, Windows Temp, Admin$ shares, Temp under AppData). Attackers may use this behavior to extract embedded payloads or staging files while blending into normal-looking system activity. It relies on process creation telemetry capturing Image and CommandLine, including parent process context.
references:
  - https://labs.sentinelone.com/meteorexpress-mysterious-wiper-paralyzes-iranian-trains-with-epic-troll
  - https://blog.malwarebytes.com/threat-intelligence/2021/08/new-variant-of-konni-malware-used-in-campaign-targetting-russia/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_expand_cabinet_files.yml
author: Bhabesh Raj, X__Junior (Nextron Systems), Huntrule Team
date: 2021-07-30
modified: 2024-11-13
tags:
  - attack.stealth
  - attack.t1218
logsource:
  category: process_creation
  product: windows
detection:
  selection_cmd:
    Image|endswith: \expand.exe
    CommandLine|contains|windash: "-F:"
  selection_folders_1:
    CommandLine|contains:
      - :\Perflogs\
      - :\ProgramData
      - :\Users\Public\
      - :\Windows\Temp\
      - \Admin$\
      - \AppData\Local\Temp\
      - \AppData\Roaming\
      - \C$\
      - \Temporary Internet
  selection_folders_2:
    - CommandLine|contains|all:
        - :\Users\
        - \Favorites\
    - CommandLine|contains|all:
        - :\Users\
        - \Favourites\
    - CommandLine|contains|all:
        - :\Users\
        - \Contacts\
  filter_optional_dell:
    ParentImage: C:\Program Files (x86)\Dell\UpdateService\ServiceShell.exe
    CommandLine|contains: C:\ProgramData\Dell\UpdateService\Temp\
  condition: selection_cmd and 1 of selection_folders_* and not 1 of filter_optional_*
falsepositives:
  - System administrator Usage
level: medium
license: DRL-1.1
related:
  - id: 9f107a84-532c-41af-b005-8d12a607639f
    type: derived

Convert

This rule as a query you can run. Uses no unlock credit.

SplunkSPL