Graph API Teams User Activity Reporting

Creating a CSV file of Teams User activity

For tenancies with thousands of users, extracting usage data from Office 365 is no mean feat. This process will allow you to extract a CSV file that contains the usage data for thousands of users.

Make a note of the application ID:

App ID: 849232c6-f6dc-450e-892a-149982db63a6

Create a certificate to authenticate the app when it accesses user data in Azure:

You will need an Azure App Registration with the correct permission assigned:

Read All User Activity Data

# Your tenant name (can something more descriptive as well)

$TenantName        = "<tenancy_name>"

# Where to export the certificate without the private key

$CerOutputPath     = "C:\Temp\PowerShellGraphCert.cer"

# What cert store you want it to be in

$StoreLocation = "Cert:\CurrentUser\My"

# Expiration date of the new certificate$ExpirationDate    = (Get-Date).AddYears(2)

# Splat for readability

$CreateCertificateSplat = @{    

    FriendlyName      = "AzureApp"

    DnsName           = $TenantName

    CertStoreLocation = $StoreLocation

    NotAfter          = $ExpirationDate    

    KeyExportPolicy   = "Exportable"    

    KeySpec           = "Signature"    

    Provider          = "Microsoft Enhanced RSA and AES Cryptographic Provider"

    HashAlgorithm     = "SHA256"

                                }

# Create certificate$Certificate = New-SelfSignedCertificate @CreateCertificateSplat

# Get certificate path$CertificatePath = Join-Path -Path $StoreLocation -ChildPath $Certificate.Thumbprint

# Export certificate without private key

Export-Certificate -Cert $CertificatePath -FilePath $CerOutputPath | Out-Null

Upload the cert to Azure 

Ensure API permissions are granted in the app
Create an access token in Powershell

$TenantName = "<your tenant name>.onmicrosoft.com"
$AppId = "<your application id"
$Certificate = Get-Item Cert:\CurrentUser\My\<self signed and uploaded cert thumbprint>
$Scope = "https://graph.microsoft.com/.default"

# Create base64 hash of certificate
$CertificateBase64Hash = [System.Convert]::ToBase64String($Certificate.GetCertHash())

# Create JWT timestamp for expiration
$StartDate = (Get-Date "1970-01-01T00:00:00Z" ).ToUniversalTime()
$JWTExpirationTimeSpan = (New-TimeSpan -Start $StartDate -End (Get-Date).ToUniversalTime().AddMinutes(2)).TotalSeconds
$JWTExpiration = [math]::Round($JWTExpirationTimeSpan,0)

# Create JWT validity start timestamp
$NotBeforeExpirationTimeSpan = (New-TimeSpan -Start $StartDate -End ((Get-Date).ToUniversalTime())).TotalSeconds
$NotBefore = [math]::Round($NotBeforeExpirationTimeSpan,0)

# Create JWT header
$JWTHeader = @{
    alg = "RS256"
    typ = "JWT"
    # Use the CertificateBase64Hash and replace/strip to match web encoding of base64
    x5t = $CertificateBase64Hash -replace '\+','-' -replace '/','_' -replace '='
}

# Create JWT payload
$JWTPayLoad = @{
    # What endpoint is allowed to use this JWT
    aud = "https://login.microsoftonline.com/$TenantName/oauth2/token"

    # Expiration timestamp
    exp = $JWTExpiration

    # Issuer = your application
    iss = $AppId

    # JWT ID: random guid
    jti = [guid]::NewGuid()

    # Not to be used before
    nbf = $NotBefore

    # JWT Subject
    sub = $AppId
}

# Convert header and payload to base64
$JWTHeaderToByte = [System.Text.Encoding]::UTF8.GetBytes(($JWTHeader | ConvertTo-Json))
$EncodedHeader = [System.Convert]::ToBase64String($JWTHeaderToByte)

$JWTPayLoadToByte =  [System.Text.Encoding]::UTF8.GetBytes(($JWTPayload | ConvertTo-Json))
$EncodedPayload = [System.Convert]::ToBase64String($JWTPayLoadToByte)

# Join header and Payload with "." to create a valid (unsigned) JWT
$JWT = $EncodedHeader + "." + $EncodedPayload

# Get the private key object of your certificate
$PrivateKey = $Certificate.PrivateKey

# Define RSA signature and hashing algorithm
$RSAPadding = [Security.Cryptography.RSASignaturePadding]::Pkcs1
$HashAlgorithm = [Security.Cryptography.HashAlgorithmName]::SHA256

# Create a signature of the JWT
$Signature = [Convert]::ToBase64String(
    $PrivateKey.SignData([System.Text.Encoding]::UTF8.GetBytes($JWT),$HashAlgorithm,$RSAPadding)
) -replace '\+','-' -replace '/','_' -replace '='

# Join the signature to the JWT with "."
$JWT = $JWT + "." + $Signature

# Create a hash with body parameters
$Body = @{
    client_id = $AppId
    client_assertion = $JWT
    client_assertion_type = "urn:ietf:params:oauth:client-assertion-type:jwt-bearer"
    scope = $Scope
    grant_type = "client_credentials"

}

$Url = "https://login.microsoftonline.com/$TenantName/oauth2/v2.0/token"

# Use the self-generated JWT as Authorization
$Header = @{
    Authorization = "Bearer $JWT"
}

# Splat the parameters for Invoke-Restmethod for cleaner code
$PostSplat = @{
    ContentType = 'application/x-www-form-urlencoded'
    Method = 'POST'
    Body = $Body
    Uri = $Url
    Headers = $Header
}

$Request = Invoke-RestMethod @PostSplat

Reference: https://adamtheautomator.com/microsoft-graph-api-powershell/