SMB Events Monitoring
Hypothesis and description
[Server Message Block](https://en.wikipedia.org/wiki/Server_Message Block) (SMB) is used by Windows to allow for file, pipe, and printer sharing over port 445/tcp. It allows for enumerating, and reading from and writing to file shares for a remote computer. Although it is heavily used by Windows servers for legitimate purposes and by users for file and printer sharing, many adversaries also use SMB to achieve Lateral Movement. Looking at this activity more closely to obtain an adequate sense of situational awareness may make it possible to detect adversaries moving between hosts in a way that deviates from normal activity. Because SMB traffic is heavy in many environments, this analytic may be difficult to turn into something that can be used to quickly detect an APT. In some cases, it may make more sense to run this analytic in a forensic fashion. Looking through and filtering its output after an intrusion has been discovered may be helpful in identifying the scope of compromise.
### Output Description
The source, destination, content, and time of each event.
- Platforms
- N/A
- Domain
- Network
- Subtypes
- PCAP
- Submitted
- 2013-01-25
- Contributors
- MITRE
ATT&CK coverage
| Technique | Tactics | Coverage |
|---|---|---|
| T1039 Data from Network Shared Drive | Collection | Moderate |
| T1021 Remote ServicesT1021.002 | Lateral Movement | Moderate |
2 techniques, 3 ATT&CK ids including sub-techniques. Links open MITRE ATT&CK.
D3FEND techniques MITRE maps to this analytic
Data model references
Fields from the CAR data model (object/action/field) the analytic reads.
Pseudocode and implementations
Although there may be more native ways to detect detailed SMB events on the host, they can be extracted out of network traffic. With the right protocol decoders, port 445 traffic can be filtered and even the file path (relative to the share) can be retrieved.
flow = search Flow:Message
smb_events = filter flow where (dest_port == "445" and protocol == "smb")
smb_events.file_name = smb_events.proto_info.file_name
output smb_writeAcross MITRE's defensive frameworks
Linked through the 2 ATT&CK techniques above.
Counter with D3FEND
Defensive techniques MITRE D3FEND maps to the same ATT&CK techniques.
- D3-STSession Termination1 shared
- D3-DNRDecoy Network Resource1 shared
- D3-NRAMNetwork Resource Access Mediation1 shared
- D3-CAAConnection Attempt Analysis1 shared
- D3-APCAApplication Protocol Command Analysis1 shared
- D3-CSPPClient-server Payload Profiling1 shared
- D3-NTCDNetwork Traffic Community Deviation1 shared
- D3-NTFNetwork Traffic Filtering1 shared
- D3-NTSANetwork Traffic Signature Analysis1 shared
- D3-PHDURAPer Host Download-Upload Ratio Analysis1 shared
- D3-PMADProtocol Metadata Anomaly Detection1 shared
- D3-RTSDRemote Terminal Session Detection1 shared