LoFP / false positives should be limited as the analytic is specific to a filename with extension .zip. filter as needed.

Techniques

• T1069
• T1069.001
• T1069.002
• T1087
• T1087.001
• T1087.002
• T1482

Sample rules

Detect AzureHound File Modifications

• source: splunk
• technicques:
  • T1087.002
  • T1069.001
  • T1482
  • T1087.001
  • T1087
  • T1069.002
  • T1069

Description

The following analytic is similar to SharpHound file modifications, but this instance covers the use of Invoke-AzureHound. AzureHound is the SharpHound equivilent but for Azure. It’s possible this may never be seen in an environment as most attackers may execute this tool remotely. Once execution is complete, a zip file with a similar name will drop 20210601090751-azurecollection.zip. In addition to the zip, multiple .json files will be written to disk, which are in the zip.

Detection logic

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Filesystem where Filesystem.file_name IN ("*-azurecollection.zip", "*-azprivroleadminrights.json", "*-azglobaladminrights.json", "*-azcloudappadmins.json", "*-azapplicationadmins.json") by Filesystem.file_create_time Filesystem.process_id  Filesystem.file_name Filesystem.file_path Filesystem.dest Filesystem.user 
| `drop_dm_object_name(Filesystem)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `detect_azurehound_file_modifications_filter`

Detect SharpHound File Modifications

• source: splunk
• technicques:
  • T1087.002
  • T1069.001
  • T1482
  • T1087.001
  • T1087
  • T1069.002
  • T1069

Description

SharpHound is used as a reconnaissance collector, ingestor, for BloodHound. SharpHound will query the domain controller and begin gathering all the data related to the domain and trusts. For output, it will drop a .zip file upon completion following a typical pattern that is often not changed. This analytic focuses on the default file name scheme. Note that this may be evaded with different parameters within SharpHound, but that depends on the operator. -randomizefilenames and -encryptzip are two examples. In addition, executing SharpHound via .exe or .ps1 without any command-line arguments will still perform activity and dump output to the default filename. Example default filename 20210601181553_BloodHound.zip. SharpHound creates multiple temp files following the same pattern 20210601182121_computers.json, domains.json, gpos.json, ous.json and users.json. Tuning may be required, or remove these json’s entirely if it is too noisy. During traige, review parallel processes for further suspicious behavior. Typically, the process executing the .ps1 ingestor will be PowerShell.

Detection logic

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Filesystem where Filesystem.file_name IN ("*bloodhound.zip", "*_computers.json", "*_gpos.json", "*_domains.json", "*_users.json", "*_groups.json", "*_ous.json", "*_containers.json") by Filesystem.file_create_time Filesystem.process_id  Filesystem.file_name Filesystem.file_path Filesystem.dest Filesystem.user
| `drop_dm_object_name(Filesystem)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `detect_sharphound_file_modifications_filter`