LoFP LoFP / support engineers, infrastructure-as-code, and vm health automation may legitimately retrieve boot diagnostics during troubleshooting. the first occurrence per principal will alert; baseline expected support users, service principals, and managed identities and exclude them if the activity is verified as authorized.

Techniques

Sample rules

Azure VM Boot Diagnostics Retrieved

Description

Identifies retrieval of Azure VM boot diagnostics data (“MICROSOFT.COMPUTE/VIRTUALMACHINES/RETRIEVEBOOTDIAGNOSTICSDATA/ACTION”) by an identity that has not performed this operation recently. Boot diagnostics expose the VM serial console log and a console screenshot, which frequently contain plaintext boot-time output such as credentials, tokens, cloud-init/agent secrets, and command history. An adversary with VM read/contributor rights can retrieve this data over the control plane, without logging into the guest or touching the network, to harvest credentials.

Detection logic

data_stream.dataset:azure.activitylogs and
    event.action:"MICROSOFT.COMPUTE/VIRTUALMACHINES/RETRIEVEBOOTDIAGNOSTICSDATA/ACTION" and
    event.outcome:(success or Success)