Sigma rule: Suspicious PowerShell IEX Execution Patterns

Rule

Title

Suspicious PowerShell IEX Execution Patterns

Status

test

Level

high

Author

Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)

Date

2022-03-24

Modified

2022-11-28

File

rules/windows/process_creation/proc_creation_win_powershell_iex_patterns.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects suspicious ways to run Invoke-Execution using IEX alias

Log source

product

windows

category

process_creation

Detection

selection_combined_1:
    Image|endswith:
        - '\powershell.exe'
        - '\pwsh.exe'
    CommandLine|contains:
        - ' | iex;'
        - ' | iex '
        - ' | iex}'
        - ' | IEX ;'
        - ' | IEX -Error'
        - ' | IEX (new'
        - ');IEX '
selection_combined_2:
    CommandLine|contains:
        - '::FromBase64String'
        - '.GetString([System.Convert]::'
selection_standalone:
    CommandLine|contains:
        - ')|iex;$'
        - ');iex($'
        - ');iex $'
        - ' | IEX | '
        - ' | iex\"'
condition: all of selection_combined_* or selection_standalone

False positives (as the rule lists them)

• Legitimate scripts that use IEX

Tags

• attack.execution
• attack.t1059.001

MITRE ATT&CK ids this rule names

• T1059.001

References

• https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/invoke-expression?view=powershell-7.2
• https://www.huntress.com/blog/slashandgrab-screen-connect-post-exploitation-in-the-wild-cve-2024-1709-cve-2024-1708

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_powershell_iex_patterns.yml