Cloud – SEC-LABS R&D

Azure Sentinel is now GA

SEC-LABS R&D 2019-09-25 0 Comments

Azure Sentinel—the cloud-native SIEM that empowers defenders is now generally available

Some of the new features are:

Workbooks are replacing dashboards, providing for richer analytics and visualizations
New Microsoft and 3rd party connectors

Detection and hunting:

Out of the box detection rules: The GitHub detection rules are now built into Sentinel.
Easy elevation of MTP alerts to Sentinel incidents.
Built-in detection rules utilizing the threat intelligence connector.
New ML models to discover malicious SSH access, fuse identity, and access data to detect 35 unique threats that span multiple stages of the kill chain. Fusion is now on by default and managed through the UI
Template playbooks now available on Github.
New threat hunting queries and libraries for Jupyter Notebooks

Incidents:

The interactive investigation graph is now publicly available.
Incidents support for tagging, comments, and assignments, both manually and automatically using playbooks.

MSSP and enterprise support:

Azure Lighthouse for multi-tenant management
RBAC support

For further information:

Pricing: https://azure.microsoft.com/en-us/pricing/details/azure-sentinel/
Product page: https://azure.microsoft.com/en-us/services/azure-sentinel/
Documentation: https://docs.microsoft.com/en-us/azure/sentinel/

Happy Hunting

Detect, Events, Respond, Security

Azure, Cloud, Sentinel, SIEM, ThreatHunting

Audit Scheduled tasks using Azure Sentinel

SEC-LABS R&D 2019-03-19 1 Comment

Azure Sentinel is a powerful cloud based SIEM solution.
This blog series will be on how to work with Sentinel.

It will be example based on different solutions which we might run into.

This first post is about how you can work with logs and get insight in Scheduled Tasks as a way for attackers to persist in your network

For further information regards Sentinel, visit https://azure.microsoft.com/en-us/services/azure-sentinel/

Scheduled Tasks

By default there are no events created if someone creates or modifieds a scheduled task. To enable logging you have to enable logging of object access.

To view current settings, use the following command:

auditpol.exe /get /category:*

Only Success is required for this. This enables us to get the event 4698

To enable logging, create a new GPO and assign the following settings (depending if you want success/failure or only success)

You also have to configure your agents to send log to your workspace, you can download the agent from the Azure Sentinel workspace / <workspace name> / Advanced Settings

Otherwise, you can add the Sentinel workspace to your existing agents

$Agent = New-Object -ComObject AgentConfigManager.MgmtSvcCfg
$ID= "<WorkspaceID>"
$Key = "<key>"
$Agent.AddCloudWorkspace($ID,$Key)
restart-service HealthService

In Azure Sentinel – Data connectors, configure Security Events

Verify heartbeats from computers


Heartbeat | summarize argmax(TimeGenerated, *) by Computer

So now we have logs from 2 computers and now we want to query Scheduled Tasks

A simple way is to just query the EventID

We can use project to format our table but we still want to get information about the tasks that were created to get a better overview

According to documentation we can use Parse operator into one or more calculated columns

https://docs.microsoft.com/en-us/azure/kusto/query/parseoperator

//Example
SecurityEvent
| where EventID == "4698"
| parse EventData with * '"SubjectUserName">' SubjectUserName '<' * '"SubjectDomainName">' SubjectDomainName '<' *

This query will

Select all events where eventid=4698
parse the column event data and look for ‘”SubjectUserName”>’
Put everyting to a column named SubjectUserName until character ‘<‘
the wildcard will run the samething again
Continue parsing until ‘”SubjectDomainName”>’
Put everything into column SubjectDomainName until character ‘<‘

To continue this to get some really useful information we continue to parse the content until we get everything we need

//Sec-Labs Demo - Sentinel Hunting for Scheduled Tasks Persistance
let start=datetime("2019-03-12T19:39:47.762Z");
let end=datetime("2019-03-19T22:39:47.762Z");
SecurityEvent
|where TimeGenerated > start and TimeGenerated < end
| where EventID == "4698"
| parse EventData with * '"SubjectUserName">' SubjectUserName '<' * '"SubjectDomainName">' SubjectDomainName '<' * '"TaskName">\\' TaskName '<' * 'Author>' Author '<' * '<Command>' SchedCommand '</Command' * 'Arguments>' SchedArgs '</Arguments' * 'WorkingDirectory>' SchedDir '&' *
| where isnotempty (SubjectUserName) 
| project TimeGenerated,SubjectUserName,Computer,Activity,SubjectDomainName,TaskName,SchedCommand,SchedArgs,SchedDir
| project-rename CreatedBy = SubjectUserName