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.
- 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 EvasionRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
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
- labs.sentinelone.comhttps://labs.sentinelone.com/meteorexpress-mysterious-wiper-paralyzes-iranian-trains-with-epic-troll
- blog.malwarebytes.comhttps://blog.malwarebytes.com/threat-intelligence/2021/08/new-variant-of-konni-malware-used-in-campaign-targetting-russia/
- github.comhttps://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_expand_cabinet_files.yml
Changelog
v2- v2Candidate ingested via manual entry.2026-07-31
- v1No 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.
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