Network Share Discovery Via Dir Command

Name:Network Share Discovery Via Dir Command
id:dc1457d0-1d9b-422e-b5a7-db46c184d9aa
version:7
date:None
author:Teoderick Contreras, Splunk
status:production
type:Hunting
Description:The following analytic detects access to Windows administrative SMB shares (Admin$, IPC$, C$) using the 'dir' command. It leverages Windows Security Event Logs with EventCode 5140 to identify this activity. This behavior is significant as it is commonly used by tools like PsExec/PaExec for staging binaries before creating and starting services on remote endpoints, a technique often employed by adversaries for lateral movement and remote code execution. If confirmed malicious, this activity could allow attackers to propagate malware, such as IcedID, across the network, leading to widespread infection and potential data breaches.
Data_source:

• -Windows Event Log Security 5140

search:`wineventlog_security`
EventCode=5140
ShareName IN (
"\\\\*\\Admin$",
"\\\\*\\C$",
"\\\\*\\IPC$"
)


```
We select only read-related operations:
0x1 = ReadData (or ListDirectory)
```

| eval AccessMask_ = tonumber(AccessMask, 16)
| where (bit_and(AccessMask_, 1) != 0)

| stats min(_time) as firstTime
max(_time) as lastTime
count

by ShareName IpAddress ObjectType SubjectUserName
SubjectDomainName IpPort AccessMask Computer

| rename Computer as dest

| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `network_share_discovery_via_dir_command_filter`

how_to_implement:To successfully implement this search, you need to be ingesting Windows Security Event Logs with 5140 EventCode enabled. The Windows TA is also required. Also enable the object Audit access success/failure in your group policy.
known_false_positives:System Administrators may use tools like "net.exe", "net1.exe", or "dir" for troubleshooting or administrations tasks. However, this will typically come only from certain users and certain systems that can be added to an allow list.
References:
  -https://thedfirreport.com/2023/05/22/icedid-macro-ends-in-nokoyawa-ransomware/
  -https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-10/security/threat-protection/auditing/event-5140#table-of-file-access-codes
  -https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-10/security/threat-protection/auditing/event-5140
drilldown_searches:
  :
analytic_story:['IcedID']

asset_type:Endpoint

mitre_attack_id:['T1135']

product:['Splunk Enterprise', 'Splunk Enterprise Security', 'Splunk Cloud']

category:endpoint

security_domain:endpoint

tags:

tests:
 name:'True Positive Test'
 attack_data:
  data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1135/net_share_discovery_via_dir/smb_access_security_xml.log
  source: XmlWinEventLog:Security
  sourcetype: XmlWinEventLog
 test_type:'unit'
manual_test:None