# T1052 - Exfiltration Over Physical Medium

## SOC Recommendation
Investigate Exfiltration Over Physical Medium activity in the context of Exfiltration: confirm scope, affected host/identity, and whether it matches expected administrative behaviour before deciding this is benign.

## D3FEND Mappings
| D3FEND Technique | Relationship | Practical SOC Action |
|---|---|---|
| Radiation Hardening | Harden | Apply Radiation Hardening to reduce this technique's viability before an incident occurs. |
| IO Port Restriction | Isolate | Apply IO Port Restriction to contain the blast radius once this technique is observed. |
| Hardware Component Inventory | Model | Use Hardware Component Inventory to establish a baseline that makes this technique's deviations easier to spot. |

## Investigation Steps
1. Review Defender for Endpoint / Defender XDR alerts and timeline for the affected host or identity.
2. Check Sentinel analytics rules and incidents correlated with this technique.
3. Review Entra ID sign-in and audit logs if the technique involves an identity or cloud resource.

## Evidence to Collect
- Host or resource affected
- Account or identity involved
- Timestamp of the activity
- Related process, file, or network artifact
- Any preceding or follow-on alerts

## Response Actions
| Action | Risk | Automation Safe | Approval Required |
|---|---|---|---|
| Contain the affected host or account | Medium | No | Yes |
| Collect and preserve evidence | Low | Yes | No |

## KQL
```kql
let drive_mount_lookback = 14d;
let query_frequency = 1h;
DataverseActivity
| distinct InstanceUrl
| join kind=inner (DeviceFileEvents
    | where TimeGenerated >= ago(query_frequency))
    on $left.InstanceUrl == $right.FileOriginUrl
| join kind=inner (MSBizAppsTerminatedEmployees()) on $left.InitiatingProcessAccountUpn == $right.UserPrincipalName
| join kind=inner (DeviceEvents
    | where TimeGenerated >= ago(drive_mount_lookback)
    | where ActionType == "UsbDriveMounted"
    | extend DriveLetter = tostring(AdditionalFields.DriveLetter)
    | summarize MountedDriveLetters = make_set(DriveLetter, 26) by DeviceId, DeviceName)
    on DeviceId
| extend TargetDriveLetter = tostring(split(FolderPath, "\\")[0])
| where set_has_element(MountedDriveLetters, TargetDriveLetter)
| join kind=inner (DeviceInfo
    | summarize arg_max(TimeGenerated, DeviceId, PublicIP) by DeviceName)
    on DeviceId
| project-rename
    UserId = UserPrincipalName
| summarize LatestEvent = arg_max(TimeGenerated, *), Files = make_set(FileName, 100) by UserId, InstanceUrl
| extend
    CloudAppId = int(32780),
    AccountName = tostring(split(UserId, '@')[0]),
    UPNSuffix = tostring(split(UserId, '@')[1])
| project
    LatestEvent,
    UserId,
    PublicIP,
    Files,
    InstanceUrl,
    CloudAppId,
    AccountName,
    UPNSuffix
```
```kql
let Alerts = SecurityAlert
| where AlertName =~ "mass download by a single user"
| where Status != 'Resolved'
| extend ipEnt = parse_json(Entities), accountEnt = parse_json(Entities)
| mv-apply tempParams = ipEnt on (
mv-expand ipEnt
| where ipEnt.Type == "ip" 
| extend IpAddress = tostring(ipEnt.Address)
)
| mv-apply tempParams = accountEnt on (
mv-expand accountEnt
| where accountEnt.Type == "account"
| extend AADUserId = tostring(accountEnt.AadUserId)
)
| extend Alert_TimeGenerated = TimeGenerated
| distinct Alert_TimeGenerated, IpAddress, AADUserId, DisplayName, Description, ProductName, ExtendedProperties, Entities, Status, CompromisedEntity
;
let CA_Events = CloudAppEvents
| where ActionType == "FileDownloaded"
| extend parsed = parse_json(RawEventData)
| extend UserId = tostring(parsed.UserId)
| extend FileName = tostring(parsed.SourceFileName)
| extend FileExtension = tostring(parsed.SourceFileExtension)
| summarize CloudAppEvent_StartTime = min(TimeGenerated), CloudAppEvent_EndTime = max(TimeGenerated), CloudAppEvent_Files = make_set(FileName), FileCount = dcount(FileName) by Application, AccountObjectId, UserId, IPAddress, City, CountryCode
| extend CloudAppEvents_Details = pack_all();
let CA_Alerts_Events = Alerts | join kind=inner (CA_Events)
on $left.AADUserId == $right.AccountObjectId and $left.IpAddress == $right.IPAddress
// Cloud app event comes before Alert
| where CloudAppEvent_EndTime <= Alert_TimeGenerated
| project Alert_TimeGenerated, UserId, AADUserId, IPAddress, CloudAppEvents_Details, CloudAppEvent_Files
;
// setup list to filter DeviceFileEvents for only files downloaded as indicated by CloudAppEvents
let CA_FileList = CA_Alerts_Events | project CloudAppEvent_Files;
CA_Alerts_Events
| join kind=inner ( DeviceFileEvents
| where ActionType in ("FileCreated", "FileRenamed")
| where FileName in~ (CA_FileList)
| summarize DeviceFileEvent_StartTime = min(TimeGenerated), DeviceFileEvent_EndTime = max(TimeGenerated), DeviceFileEvent_Files = make_set(FolderPath), DeviceFileEvent_FileCount = dcount(FolderPath) by InitiatingProcessAccountUpn, DeviceId, DeviceName, InitiatingProcessFolderPath, InitiatingProcessParentFileName//, InitiatingProcessCommandLine
| extend DeviceFileEvents_Details = pack_all()
) on $left.UserId == $right.InitiatingProcessAccountUpn
| where DeviceFileEvent_StartTime >= Alert_TimeGenerated
| join kind=inner (
// get device events where a USB drive was mounted
DeviceEvents
| where ActionType == "UsbDriveMounted"
| extend parsed = parse_json(AdditionalFields)
| extend USB_DriveLetter = tostring(AdditionalFields.DriveLetter), USB_ProductName = tostring(AdditionalFields.ProductName), USB_Volume = tostring(AdditionalFields.Volume)
| where isnotempty(USB_DriveLetter)
| project USB_TimeGenerated = TimeGenerated, DeviceId, USB_DriveLetter, USB_ProductName, USB_Volume
| extend USB_Details = pack_all()
)  
on DeviceId
// USB event occurs after the Alert
| where USB_TimeGenerated >= Alert_TimeGenerated
| mv-expand DeviceFileEvent_Files
| extend DeviceFileEvent_Files = tostring(DeviceFileEvent_Files)
// make sure that we only pickup the files that have the USB drive letter
| where DeviceFileEvent_Files startswith USB_DriveLetter
| summarize USB_Drive_MatchedFiles = make_set_if(DeviceFileEvent_Files, DeviceFileEvent_Files startswith USB_DriveLetter) by Alert_TimeGenerated, USB_TimeGenerated, UserId, AADUserId, DeviceId, DeviceName, IPAddress, CloudAppEvents_Details = tostring(CloudAppEvents_Details), DeviceFileEvents_Details = tostring(DeviceFileEvents_Details), USB_Details = tostring(USB_Details)
| extend InitiatingProcessFileName = tostring(split(todynamic(DeviceFileEvents_Details).InitiatingProcessFolderPath, "\\")[-1]), InitiatingProcessFolderPath = tostring(todynamic(DeviceFileEvents_Details).InitiatingProcessFolderPath)
| extend HostName = tostring(split(DeviceName, ".")[0]), DomainIndex = toint(indexof(DeviceName, '.'))
| extend HostNameDomain = iff(DeviceName != -1, substring(DeviceName, DomainIndex + 1), DeviceName)
| extend AccountName = tostring(split(UserId, "@")[0]), AccountUPNSuffix = tostring(split(UserId, "@")[1])
| project-away DomainIndex
```

## Escalation Criteria
- Exfiltration Over Physical Medium activity observed on a privileged account or critical system.
- Activity follows or precedes other suspicious behaviour in the same investigation.
- Automated triage cannot confidently rule out malicious intent.

## False Positive Considerations
- Legitimate administrative or maintenance activity matching this pattern.
- Approved security testing or red team exercise.
- Known benign software producing similar telemetry.

Generated by SOC Response Atlas by Basyrix.