# [HIGH] From package to postinstall payload: Inside the Mastra npm supply chain compromise

**Source:** Microsoft Security Blog
**Published:** 2026-06-18
**Article:** https://www.microsoft.com/en-us/security/blog/2026/06/17/postinstall-payload-inside-mastra-npm-supply-chain-compromise/

## Threat Profile

Tags 
Malware 
npm 
Content types 
Research 
Products and services 
Microsoft Defender 
Topics 
Actionable threat insights 
Microsoft Threat Intelligence observed a large-scale npm supply chain attack affecting 140+ packages across the mastra and @mastra scopes on the npm registry. Microsoft shared its findings with the npm security team, and the compromised packages have been removed and the attacker’s publish access to the @mastra scope has been revoked. The compromise originated from the take…

## Indicators of Compromise (high-fidelity only)

- **IPv4 (defanged):** `23.254.164.92`
- **IPv4 (defanged):** `23.254.164.123`
- **Domain (defanged):** `hwsrv-1327786.hostwindsdns.com`
- **Domain (defanged):** `hwsrv-1327785.hostwindsdns.com`
- **SHA256:** `b122a9873bedf145ae2a7fd024b5f309007dbb025149f4dc4ac3f7e4f32a36a4`
- **SHA256:** `c38954e85bf5433e61e7c8f4230336695624ae88b6953afabf7bf817aa91b638`
- **SHA256:** `cdec8b20338beb708b5be8d3d7a3041a35a8b0fb92f9186262f312d55ff82066`
- **SHA256:** `9570f77a5e1511869f4e554e7166df9fde081f2583e293c2569621792ed7d9c9`
- **SHA256:** `221c45a790dec2a296af57969e1165a16f8f49733aeab64c0bbd768d9943badf`

## MITRE ATT&CK Techniques

- **T1071.001** — Web Protocols
- **T1071.004** — DNS
- **T1071** — Application Layer Protocol
- **T1005** — Data from Local System
- **T1539** — Steal Web Session Cookie
- **T1555.003** — Credentials from Web Browsers
- **T1021.002** — SMB/Windows Admin Shares
- **T1569.002** — Service Execution
- **T1059.001** — PowerShell
- **T1027** — Obfuscated Files or Information
- **T1195.002** — Compromise Software Supply Chain
- **T1543.001** — Persistence (article-specific)
- **T1547.001** — Persistence (article-specific)
- **T1059.007** — JavaScript
- **T1546.016** — Installer Packages
- **T1105** — Ingress Tool Transfer
- **T1571** — Non-Standard Port
- **T1547.001** — Registry Run Keys / Startup Folder
- **T1036.005** — Match Legitimate Resource Name or Location
- **T1217** — Browser Information Discovery
- **T1518** — Software Discovery
- **T1518.001** — Security Software Discovery

## Kill chain phases observed

_(none detected from narrative keywords)_

## Recommended hunts

### Mastra npm supply chain: easy-day-js postinstall dropper (node setup.cjs --no-warnings)

`UC_0_9` · phase: **install** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name IN ("node.exe","node") AND Processes.process="*setup.cjs*" AND Processes.process="*--no-warnings*" by Processes.user Processes.dest Processes.process_name Processes.process Processes.parent_process_name Processes.parent_process Processes.process_hash | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(7d)
| where FileName in~ ("node.exe","node")
| where ProcessCommandLine has "setup.cjs" and ProcessCommandLine has "--no-warnings"
| where InitiatingProcessFileName in~ ("npm.exe","node.exe","yarn.exe","pnpm.exe","npm-cli.js","npm","node","yarn","pnpm","cmd.exe","powershell.exe")
   or ProcessCommandLine has_any (@"\easy-day-js\", "easy-day-js/setup.cjs")
| project Timestamp, DeviceName, AccountName, FolderPath, ProcessCommandLine, SHA256, InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessParentFileName
| sort by Timestamp desc
```

### Mastra C2 beacon: node.exe to Hostwinds 23.254.164.92:8000 / .123:443

`UC_0_10` · phase: **c2** · confidence: **Medium** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Network_Traffic.All_Traffic where All_Traffic.dest IN ("23.254.164.92","23.254.164.123") OR All_Traffic.app IN ("node.exe","node") AND All_Traffic.dest IN ("23.254.164.92","23.254.164.123") by All_Traffic.src All_Traffic.dest All_Traffic.dest_port All_Traffic.app All_Traffic.user | `drop_dm_object_name(All_Traffic)` | append [| tstats `summariesonly` count from datamodel=Network_Resolution.DNS where DNS.query IN ("hwsrv-1327785.hostwindsdns.com","hwsrv-1327786.hostwindsdns.com") by DNS.src DNS.query DNS.answer | `drop_dm_object_name(DNS)`] | sort 0 - lastTime
```

**Defender KQL:**
```kql
union
(DeviceNetworkEvents
  | where Timestamp > ago(14d)
  | where RemoteIP in ("23.254.164.92","23.254.164.123")
  | where RemotePort in (8000, 443)
  | project Timestamp, DeviceName, RemoteIP, RemotePort, RemoteUrl, InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessSHA256),
(DeviceEvents
  | where Timestamp > ago(14d)
  | where ActionType == "DnsQueryResponse"
  | where AdditionalFields has_any ("hwsrv-1327785.hostwindsdns.com","hwsrv-1327786.hostwindsdns.com")
  | project Timestamp, DeviceName, ActionType, AdditionalFields, InitiatingProcessFileName)
| sort by Timestamp desc
```

### Mastra implant Windows persistence: NvmProtocal Run key + NodePackages drop

`UC_0_11` · phase: **install** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where (Registry.registry_path="*\\CurrentVersion\\Run*" AND (Registry.registry_value_name="NvmProtocal" OR Registry.registry_value_data="*\\ProgramData\\NodePackages\\*" OR Registry.registry_value_data="*protocal.cjs*")) by Registry.dest Registry.user Registry.registry_path Registry.registry_value_name Registry.registry_value_data Registry.process_name | `drop_dm_object_name(Registry)` | append [| tstats `summariesonly` count from datamodel=Endpoint.Filesystem where (Filesystem.file_name="protocal.cjs" OR Filesystem.file_path="*\\ProgramData\\NodePackages\\*") by Filesystem.dest Filesystem.file_path Filesystem.file_name Filesystem.process_name | `drop_dm_object_name(Filesystem)`] | sort 0 - lastTime
```

**Defender KQL:**
```kql
union
(DeviceRegistryEvents
  | where Timestamp > ago(14d)
  | where ActionType in ("RegistryValueSet","RegistryKeyCreated")
  | where RegistryKey has @"\CurrentVersion\Run"
  | where RegistryValueName =~ "NvmProtocal"
        or RegistryValueData has_any (@"\ProgramData\NodePackages\", "protocal.cjs")
  | project Timestamp, DeviceName, ActionType, RegistryKey, RegistryValueName, RegistryValueData, InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessAccountName),
(DeviceFileEvents
  | where Timestamp > ago(14d)
  | where FileName =~ "protocal.cjs" or FolderPath has @"\ProgramData\NodePackages\"
  | project Timestamp, DeviceName, ActionType, FileName, FolderPath, SHA256, InitiatingProcessFileName, InitiatingProcessCommandLine)
| sort by Timestamp desc
```

### Mastra implant credential access: node.exe reading crypto wallet extensions / browser History

`UC_0_12` · phase: **actions** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Filesystem where Filesystem.process_name IN ("node.exe","node") AND (Filesystem.file_path="*\\User Data\\*\\Local Extension Settings\\*" OR Filesystem.file_path="*\\User Data\\*\\Extensions\\*" OR Filesystem.file_path="*\\User Data\\*\\History*" OR Filesystem.file_path="*\\User Data\\*\\Login Data*" OR Filesystem.file_path="*\\User Data\\*\\Cookies*" OR Filesystem.file_name="browser-hist-*") by Filesystem.dest Filesystem.user Filesystem.process_name Filesystem.file_path Filesystem.file_name Filesystem.action | `drop_dm_object_name(Filesystem)` | sort 0 - lastTime
```

**Defender KQL:**
```kql
DeviceFileEvents
| where Timestamp > ago(14d)
| where InitiatingProcessFileName in~ ("node.exe","node")
| where (FolderPath has_any (@"\User Data\Default\Local Extension Settings\",
                              @"\User Data\Default\Extensions\",
                              @"\User Data\Default\History",
                              @"\User Data\Default\Login Data",
                              @"\User Data\Default\Cookies",
                              @"\Brave-Browser\User Data\",
                              @"\Microsoft\Edge\User Data\"))
   or FileName startswith "browser-hist-"
| project Timestamp, DeviceName, ActionType, FileName, FolderPath, InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessAccountName
| sort by Timestamp desc
```

### Mastra implant discovery: PowerShell child of node.exe running Get-StartApps / Get-AppxPackage

`UC_0_13` · phase: **actions** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name IN ("node.exe","node") AND Processes.process_name IN ("powershell.exe","pwsh.exe") AND (Processes.process="*Get-StartApps*" OR Processes.process="*Get-AppxPackage*" OR Processes.process="*\\Uninstall*") by Processes.user Processes.dest Processes.parent_process_name Processes.parent_process Processes.process_name Processes.process | `drop_dm_object_name(Processes)` | sort 0 - lastTime
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(14d)
| where InitiatingProcessFileName in~ ("node.exe","node")
| where FileName in~ ("powershell.exe","pwsh.exe")
| where ProcessCommandLine has_any ("Get-StartApps","Get-AppxPackage",@"\Microsoft\Windows\CurrentVersion\Uninstall")
| project Timestamp, DeviceName, AccountName, ProcessCommandLine, InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessAccountName
| sort by Timestamp desc
```

### Beaconing — periodic outbound to small set of destinations

`UC_BEACONING` · phase: **c2** · confidence: **Medium**

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count, values(All_Traffic.dest_port) AS ports
    from datamodel=Network_Traffic.All_Traffic
    where All_Traffic.action="allowed" AND All_Traffic.dest_category!="internal"
    by _time span=10s, All_Traffic.src, All_Traffic.dest
| `drop_dm_object_name(All_Traffic)`
| streamstats current=f last(_time) AS prev_time by src, dest
| eval delta = _time - prev_time
| stats avg(delta) AS avg_delta stdev(delta) AS sd_delta count by src, dest
| where count > 30 AND sd_delta < 5 AND avg_delta>=30 AND avg_delta<=600
| sort - count
```

**Defender KQL:**
```kql
DeviceNetworkEvents
| where Timestamp > ago(1d)
| where RemoteIPType == "Public" and ActionType == "ConnectionSuccess"
| project DeviceName, RemoteIP, RemotePort, Timestamp
| sort by DeviceName asc, RemoteIP asc, RemotePort asc, Timestamp asc
| extend prev_dev = prev(DeviceName, 1), prev_ip = prev(RemoteIP, 1),
         prev_port = prev(RemotePort, 1), prev_ts = prev(Timestamp, 1)
| where DeviceName == prev_dev and RemoteIP == prev_ip and RemotePort == prev_port
| extend delta_sec = datetime_diff('second', Timestamp, prev_ts)
| summarize conn_count = count(), avg_delta = avg(delta_sec), stdev_delta = stdev(delta_sec)
    by DeviceName, RemoteIP, RemotePort
| where conn_count > 30 and avg_delta between (30.0 .. 600.0) and stdev_delta < 5.0
| order by conn_count desc
```

### Crypto-wallet file/keystore access by non-wallet process

`UC_CRYPTO_WALLET` · phase: **actions** · confidence: **High**

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime
    from datamodel=Endpoint.Filesystem
    where (Filesystem.file_path="*\Ethereum\keystore\*"
        OR Filesystem.file_path="*\Bitcoin\wallet.dat"
        OR Filesystem.file_path="*\Exodus\exodus.wallet*"
        OR Filesystem.file_path="*\Electrum\wallets\*"
        OR Filesystem.file_path="*\MetaMask\*"
        OR Filesystem.file_path="*\Phantom\*"
        OR Filesystem.file_path="*\Atomic\Local Storage\*")
      AND NOT Filesystem.process_name IN ("MetaMask.exe","Exodus.exe","Atomic.exe","electrum.exe","Bitcoin.exe","Phantom.exe")
    by Filesystem.dest, Filesystem.process_name, Filesystem.file_path, Filesystem.user
| `drop_dm_object_name(Filesystem)`
```

**Defender KQL:**
```kql
DeviceFileEvents
| where Timestamp > ago(7d)
| where InitiatingProcessAccountName !endswith "$"
| where FolderPath has_any (@"\Ethereum\keystore\", @"\Bitcoin\", @"\Exodus\", @"\Electrum\wallets\", @"\MetaMask\", @"\Phantom\", @"\Atomic\Local Storage\")
| where InitiatingProcessFileName !in~ ("MetaMask.exe","Exodus.exe","Atomic.exe","electrum.exe","Bitcoin.exe","Phantom.exe")
| project Timestamp, DeviceName, InitiatingProcessAccountName, InitiatingProcessFileName, FolderPath, FileName, ActionType
```

### Infostealer — non-browser process accessing browser cookie/login DBs

`UC_BROWSER_STEALER` · phase: **actions** · confidence: **High**

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime
    from datamodel=Endpoint.Filesystem
    where (Filesystem.file_path="*\Google\Chrome\User Data\*\Login Data*"
        OR Filesystem.file_path="*\Google\Chrome\User Data\*\Cookies*"
        OR Filesystem.file_path="*\Microsoft\Edge\User Data\*\Login Data*"
        OR Filesystem.file_path="*\Mozilla\Firefox\Profiles\*\logins.json*"
        OR Filesystem.file_path="*\Mozilla\Firefox\Profiles\*\cookies.sqlite*")
      AND NOT Filesystem.process_name IN ("chrome.exe","msedge.exe","firefox.exe","brave.exe","opera.exe")
    by Filesystem.dest, Filesystem.process_name, Filesystem.file_path, Filesystem.user
| `drop_dm_object_name(Filesystem)`
```

**Defender KQL:**
```kql
DeviceFileEvents
| where Timestamp > ago(7d)
| where InitiatingProcessAccountName !endswith "$"
| where FolderPath has_any (@"\Google\Chrome\User Data\", @"\Microsoft\Edge\User Data\", @"\Mozilla\Firefox\Profiles\")
| where FileName in~ ("Login Data","Cookies","logins.json","cookies.sqlite")
| where InitiatingProcessFileName !in~ ("chrome.exe","msedge.exe","firefox.exe","brave.exe","opera.exe")
| project Timestamp, DeviceName, InitiatingProcessAccountName, InitiatingProcessFileName, FolderPath, FileName, ActionType
```

### Remote service execution — PsExec / SMB lateral movement

`UC_LATERAL_PSEXEC` · phase: **actions** · confidence: **High**

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime
    from datamodel=Endpoint.Processes
    where Processes.process_name IN ("psexec.exe","psexesvc.exe","paexec.exe","smbexec.py")
       OR (Processes.process_name="wmic.exe" AND Processes.process="*/node:*")
    by Processes.dest, Processes.user, Processes.process_name, Processes.process, Processes.parent_process_name
| `drop_dm_object_name(Processes)`
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(7d)
| where AccountName !endswith "$"
| where FileName in~ ("psexec.exe","psexesvc.exe","paexec.exe","smbexec.py")
   or (FileName =~ "wmic.exe" and ProcessCommandLine has "/node:")
| project Timestamp, DeviceName, AccountName, FileName, ProcessCommandLine, InitiatingProcessFileName
| order by Timestamp desc
```

### PowerShell encoded / obfuscated command

`UC_PS_OBFUSCATED` · phase: **exploit** · confidence: **High**

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime
    from datamodel=Endpoint.Processes
    where Processes.process_name IN ("powershell.exe","pwsh.exe")
      AND (Processes.process="*-enc *" OR Processes.process="*EncodedCommand*"
        OR Processes.process="*FromBase64String*" OR Processes.process="*-nop*"
        OR Processes.process="*-w hidden*" OR Processes.process="*Invoke-Expression*"
        OR Processes.process="*IEX(*" OR Processes.process="*DownloadString*"
        OR Processes.process="*Net.WebClient*")
    by Processes.dest, Processes.user, Processes.process_name, Processes.process, Processes.parent_process_name
| `drop_dm_object_name(Processes)`
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(7d)
| where AccountName !endswith "$"
| where FileName in~ ("powershell.exe","pwsh.exe")
| where ProcessCommandLine matches regex @"(?i)(-enc|encodedcommand|frombase64string|-nop|-w\s+hidden|invoke-expression|iex\s*\(|downloadstring|net\.webclient)"
| project Timestamp, DeviceName, AccountName, ProcessCommandLine,
          InitiatingProcessFileName, InitiatingProcessCommandLine
```

### Trusted vendor binary / installer launching unusual children

`UC_SUPPLY_CHAIN` · phase: **exploit** · confidence: **Medium**

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime
    from datamodel=Endpoint.Processes
    where Processes.parent_process_name IN ("setup.exe","installer.exe","update.exe")
      AND Processes.process_name IN ("powershell.exe","cmd.exe","rundll32.exe","regsvr32.exe","mshta.exe","wscript.exe","cscript.exe","wmic.exe","bitsadmin.exe")
    by Processes.dest, Processes.user, Processes.parent_process_name, Processes.process_name, Processes.process
| `drop_dm_object_name(Processes)`
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(7d)
| where AccountName !endswith "$"
| where InitiatingProcessFileName in~ ("setup.exe","installer.exe","update.exe")
| where FileName in~ ("powershell.exe","cmd.exe","rundll32.exe","regsvr32.exe","mshta.exe","wscript.exe","cscript.exe","wmic.exe","bitsadmin.exe")
| project Timestamp, DeviceName, AccountName, InitiatingProcessFileName, FileName, ProcessCommandLine
```

### Article-specific behavioural hunt — From package to postinstall payload: Inside the Mastra npm supply chain compromi

`UC_0_8` · phase: **exploit** · confidence: **High**

**Splunk SPL (CIM):**
```spl
``` Article-specific bespoke detection — From package to postinstall payload: Inside the Mastra npm supply chain compromi ```
| tstats `summariesonly` count earliest(_time) AS firstTime latest(_time) AS lastTime
    from datamodel=Endpoint.Processes
    where (Processes.process_name IN ("node.js","dayjs.min.js") OR Processes.process_path="*C:\ProgramData\NodePackages\*")
    by Processes.dest, Processes.user, Processes.process_name,
       Processes.process, Processes.parent_process_name, Processes.process_path
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| append [
| tstats `summariesonly` count
    from datamodel=Endpoint.Filesystem
    where Filesystem.action IN ("created","modified")
      AND (Filesystem.file_path="*C:\ProgramData\NodePackages\*" OR Filesystem.file_path="*/Library/NodePackages/*" OR Filesystem.file_name IN ("node.js","dayjs.min.js"))
    by Filesystem.dest, Filesystem.user, Filesystem.process_name,
       Filesystem.file_path, Filesystem.file_name
| `drop_dm_object_name(Filesystem)`
]
```

**Defender KQL:**
```kql
// Article-specific bespoke detection — From package to postinstall payload: Inside the Mastra npm supply chain compromi
// Hunts the actual binaries / paths / commandline fragments named
// in the article instead of a generic technique-class template.
DeviceProcessEvents
| where Timestamp > ago(30d)
| where (FileName in~ ("node.js", "dayjs.min.js") or FolderPath has_any ("C:\ProgramData\NodePackages\"))
| project Timestamp, DeviceName, AccountName, FileName,
          FolderPath, ProcessCommandLine,
          InitiatingProcessFileName, InitiatingProcessCommandLine
| order by Timestamp desc

// File-creation events for the named binaries / paths
DeviceFileEvents
| where Timestamp > ago(30d)
| where ActionType in ("FileCreated","FileModified")
| where (FolderPath has_any ("C:\ProgramData\NodePackages\", "/Library/NodePackages/") or FileName in~ ("node.js", "dayjs.min.js"))
| project Timestamp, DeviceName, AccountName, FolderPath,
          FileName, ActionType, InitiatingProcessFileName,
          InitiatingProcessCommandLine
| order by Timestamp desc
```

### IOC-driven hunts (use shared templates)

These are standard IOC-substitution hunts — the canonical SPL and KQL live once in [`_TEMPLATES.md`](../_TEMPLATES.md), so we don't repeat the same boilerplate on every CVE / hash / network-IOC briefing.

- **Network connections to article IPs / domains** ([template](../_TEMPLATES.md#network-ioc)) — phase: **c2**, confidence: **High**
  - IP / domain IOC(s): `23.254.164.92`, `23.254.164.123`, `hwsrv-1327786.hostwindsdns.com`, `hwsrv-1327785.hostwindsdns.com`

- **File hash IOCs — endpoint file/process match** ([template](../_TEMPLATES.md#hash-ioc)) — phase: **install**, confidence: **High**
  - file hash IOC(s): `b122a9873bedf145ae2a7fd024b5f309007dbb025149f4dc4ac3f7e4f32a36a4`, `c38954e85bf5433e61e7c8f4230336695624ae88b6953afabf7bf817aa91b638`, `cdec8b20338beb708b5be8d3d7a3041a35a8b0fb92f9186262f312d55ff82066`, `9570f77a5e1511869f4e554e7166df9fde081f2583e293c2569621792ed7d9c9`, `221c45a790dec2a296af57969e1165a16f8f49733aeab64c0bbd768d9943badf`


## Why this matters

Severity classified as **HIGH** based on: IOCs present, 14 use case(s) fired, 22 technique(s) inferred. Read the full article for actor attribution, tooling details, and any defanged IOCs in the body that aren't visible in the RSS summary.