TEARDROP memory-only dropper

Status: available
Severity: high
Time window: 1d
Source: github.com/Azure/Azure-Sentinel

Identifies SolarWinds TEARDROP memory-only dropper IOCs in Window's defender Exploit Guard activity References: - https://www.fireeye.com/blog/threat-research/2020/12/evasive-attacker-leverages-solarwinds-supply-chain-compromises-with-sunburst-backdoor.html - https://gist.github.com/olafhartong/71ffdd4cab4b6acd5cbcd1a0691ff82f

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059` Command and Scripting Interpreter
Persistence	`T1543` Create or Modify System Process
Stealth	`T1027` Obfuscated Files or Information

Telemetry coverage

Platform	Record / event type
Microsoft Defender for Endpoint	`DeviceEvents` action `ExploitGuardNonMicrosoftSignedBlocked`: Exploit Guard non-Microsoft signed image (blocked)

Rule body

id: 738702fd-0a66-42c7-8586-e30f0583f8fe
name: TEARDROP memory-only dropper
description: |
  Identifies SolarWinds TEARDROP memory-only dropper IOCs in Window's defender Exploit Guard activity
  References:
  - https://www.fireeye.com/blog/threat-research/2020/12/evasive-attacker-leverages-solarwinds-supply-chain-compromises-with-sunburst-backdoor.html
  - https://gist.github.com/olafhartong/71ffdd4cab4b6acd5cbcd1a0691ff82f
severity: High
status: Available
requiredDataConnectors:
  - connectorId: MicrosoftThreatProtection
    dataTypes:
      - DeviceEvents
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Execution
  - Persistence
  - DefenseEvasion
relevantTechniques:
  - T1543
  - T1059
  - T1027
tags:
  - Sunburst
  - Solorigate
  - NOBELIUM
query:  |
  DeviceEvents
  | where ActionType has "ExploitGuardNonMicrosoftSignedBlocked"
  | where InitiatingProcessFileName has "svchost.exe" and FileName has "NetSetupSvc.dll"
  | extend HashAlgorithm = "SHA1"
  | extend HostName = tostring(split(DeviceName, ".")[0]), DomainIndex = toint(indexof(DeviceName, '.'))
  | extend HostNameDomain = iff(DomainIndex != -1, substring(DeviceName, DomainIndex + 1), DeviceName)
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: FullName 
        columnName: DeviceName
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: HostNameDomain
  - entityType: Account
    fieldMappings:
      - identifier: FullName 
        columnName: InitiatingProcessAccountUpn
      - identifier: Name
        columnName: InitiatingProcessAccountName
      - identifier: UPNSuffix
        columnName: InitiatingProcessAccountDomain
  - entityType: FileHash
    fieldMappings:
      - identifier: Algorithm
        columnName: HashAlgorithm
      - identifier: Value
        columnName: InitiatingProcessSHA1
version: 1.0.6
kind: Scheduled

Stages and Predicates

Stage 1: `source`

DeviceEvents

Stage 2: `where`

| where ActionType has "ExploitGuardNonMicrosoftSignedBlocked"

Stage 3: `where`

| where InitiatingProcessFileName has "svchost.exe" and FileName has "NetSetupSvc.dll"

Stage 4: `extend` (3 consecutive steps)

| extend HashAlgorithm = "SHA1"
| extend HostName = tostring(split(DeviceName, ".")[0]), DomainIndex = toint(indexof(DeviceName, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(DeviceName, DomainIndex + 1), DeviceName)

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`ActionType`	match	`ExploitGuardNonMicrosoftSignedBlocked` transforms: `term`	`field:"ActionType" kind:match value:"ExploitGuardNonMicrosoftSignedBlocked"`
`FileName`	match	`NetSetupSvc.dll` transforms: `term`	`field:"file_name" kind:match value:"NetSetupSvc.dll"`
`InitiatingProcessFileName`	match	`svchost.exe` transforms: `term`	`field:"parent_process_name" kind:match value:"svchost.exe"`

Output fields

These fields are emitted when the rule matches.

Field	Source
`HashAlgorithm`	`extend`
`DomainIndex`	`extend`
`HostName`	`extend`
`HostNameDomain`	`extend`

TEARDROP memory-only dropper

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: extend (3 consecutive steps)

Indicators

Output fields

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `extend` (3 consecutive steps)