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AnomalousSMBSessionsCreated.md

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Anomalous amount of SMB sessions created (BloodHound)

Query Information

MITRE ATT&CK Technique(s)

Technique ID Title Link
T1018 Remote System Discovery https://attack.mitre.org/techniques/T1018

Description

This detection rule is aimed to detect a host that performs SMB Discovery by alerting if a device creates more then 100 unique SMB sessions within 15 minutes. That is one of the characteristics of bloodhound. The SMB sessions can be used to identify remote systems.

Risk

A actor has gotten access to a system en performs a scan to identify possible lateral movement paths.

Defender XDR

DeviceNetworkEvents
| where ingestion_time() > ago(1h)
| where RemotePort == 445
| summarize
     TotalIpsAccessed = dcount(RemoteIP),
     RemoteIPs = make_set(RemoteIP),
     arg_max(Timestamp, *)
     by DeviceName, bin(Timestamp, 15m)
| where TotalIpsAccessed > 100 // Can be adjusted to reduce false positives
| project-reorder
     Timestamp,
     DeviceName,
     InitiatingProcessAccountDomain,
     InitiatingProcessAccountName,
     InitiatingProcessCommandLine,
     InitiatingProcessFolderPath

Sentinel

DeviceNetworkEvents
| where ingestion_time() > ago(1h)
| where RemotePort == 445
| summarize
     TotalIpsAccessed = dcount(RemoteIP),
     RemoteIPs = make_set(RemoteIP),
     arg_max(TimeGenerated, *)
     by DeviceName, bin(TimeGenerated, 15m)
| where TotalIpsAccessed > 100 // Can be adjusted to reduce false positives
| project-reorder
     TimeGenerated,
     DeviceName,
     InitiatingProcessAccountDomain,
     InitiatingProcessAccountName,
     InitiatingProcessCommandLine,
     InitiatingProcessFolderPath

Versions

Version Comment
1.0 Initial commit
1.1 Timespan update