Sigma rule: Exchange PowerShell Snap-Ins Usage

Rule

Title

Exchange PowerShell Snap-Ins Usage

Status

test

Level

high

Author

FPT.EagleEye, Nasreddine Bencherchali (Nextron Systems)

Date

2021-03-03

Modified

2023-03-24

File

rules/windows/process_creation/proc_creation_win_powershell_snapins_hafnium.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects adding and using Exchange PowerShell snap-ins to export mailbox data. As seen used by HAFNIUM and APT27

Log source

product

windows

category

process_creation

Detection

selection_img:
    - Image|endswith:
          - '\powershell.exe'
          - '\pwsh.exe'
    - OriginalFileName:
          - 'PowerShell.EXE'
          - 'pwsh.dll'
selection_cli:
    CommandLine|contains: 'Add-PSSnapin'
selection_module:
    CommandLine|contains:
        - 'Microsoft.Exchange.Powershell.Snapin'
        - 'Microsoft.Exchange.Management.PowerShell.SnapIn'
filter_msiexec:
    # ParentCommandLine: C:\Windows\System32\MsiExec.exe -Embedding C9138ECE2536CB4821EB5F55D300D88E E Global\MSI0000
    ParentImage: 'C:\Windows\System32\msiexec.exe'
    CommandLine|contains: '$exserver=Get-ExchangeServer ([Environment]::MachineName) -ErrorVariable exerr 2> $null'
condition: all of selection_* and not 1 of filter_*

False positives (as the rule lists them)

• Unknown

Tags

• attack.execution
• attack.t1059.001
• attack.collection
• attack.t1114

MITRE ATT&CK ids this rule names

• T1059.001
• T1114

References

• https://www.volexity.com/blog/2021/03/02/active-exploitation-of-microsoft-exchange-zero-day-vulnerabilities/
• https://www.microsoft.com/security/blog/2021/03/02/hafnium-targeting-exchange-servers/
• https://www.intrinsec.com/apt27-analysis/

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_snapins_hafnium.yml