# [HIGH] Mastra npm Supply Chain Attack: 140+ Packages Backdoored via easy-day-js Typosquat

**Source:** StepSecurity
**Published:** 2026-06-18
**Article:** https://www.stepsecurity.io/blog/mastra-npm-packages-compromised-using-easy-day-js

## Threat Profile

Back to Blog Threat Intel @mastra npm Packages Compromised On 2026-06-17, an attacker with access to the @mastra npm organization published malicious new versions of 13 packages across the Mastra AI framework ecosystem. Each infected package adds easy-day-js — a newly created typosquat of the popular dayjs date library — as a production dependency. The easy-day-js@1.11.22 package contains a postinstall hook that runs a heavily obfuscated setup.cjs file, which downloads and executes a second-stag…

## Indicators of Compromise (high-fidelity only)

- **IPv4 (defanged):** `23.254.164.92`
- **IPv4 (defanged):** `23.254.164.123`

## MITRE ATT&CK Techniques

- **T1071.001** — Web Protocols
- **T1071.004** — DNS
- **T1071** — Application Layer Protocol
- **T1059.001** — PowerShell
- **T1027** — Obfuscated Files or Information
- **T1195.002** — Compromise Software Supply Chain
- **T1204.002** — User Execution: Malicious File
- **T1105** — Ingress Tool Transfer
- **T1041** — Exfiltration Over C2 Channel
- **T1059.007** — JavaScript
- **T1546.016** — Installer Packages
- **T1083** — File and Directory Discovery
- **T1082** — System Information Discovery
- **T1070.004** — File Deletion
- **T1564.003** — Hidden Window

## Kill chain phases observed

_(none detected from narrative keywords)_

## Recommended hunts

### Mastra supply-chain C2 traffic to 23.254.164.92 / 23.254.164.123

`UC_13_5` · phase: **c2** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats summariesonly=true count min(_time) as firstTime max(_time) as lastTime values(All_Traffic.app) as app values(All_Traffic.src) as src from datamodel=Network_Traffic.All_Traffic where (All_Traffic.dest IN ("23.254.164.92","23.254.164.123")) by All_Traffic.dest All_Traffic.dest_port All_Traffic.src All_Traffic.user
| `drop_dm_object_name(All_Traffic)`
| eval campaign="mastra-easy-day-js-supply-chain"
| convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
DeviceNetworkEvents
| where Timestamp > ago(14d)
| where RemoteIP in ("23.254.164.92","23.254.164.123")
| project Timestamp, DeviceName, RemoteIP, RemotePort, RemoteUrl, Protocol, ActionType,
          InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessFolderPath,
          InitiatingProcessAccountName, InitiatingProcessParentFileName
| order by Timestamp desc
```

### Node.js postinstall executing setup.cjs --no-warnings (easy-day-js dropper)

`UC_13_6` · phase: **install** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats summariesonly=true count min(_time) as firstTime max(_time) as lastTime values(Processes.process) as cmdline values(Processes.parent_process_name) as parent values(Processes.parent_process) as parent_cmd values(Processes.user) as user from datamodel=Endpoint.Processes where Processes.process_name="node.exe" AND Processes.process="*setup.cjs*" AND Processes.process="*--no-warnings*" by Processes.dest Processes.process_name
| `drop_dm_object_name(Processes)`
| convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(14d)
| where FileName in~ ("node.exe","node")
| where ProcessCommandLine has "setup.cjs" and ProcessCommandLine has "--no-warnings"
| extend FromNodeModules = ProcessCommandLine has @"node_modules\easy-day-js" or InitiatingProcessCommandLine has @"node_modules\easy-day-js" or InitiatingProcessFolderPath has @"node_modules\easy-day-js"
| project Timestamp, DeviceName, AccountName, FileName, FolderPath, ProcessCommandLine,
          InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessParentFileName,
          FromNodeModules
| order by Timestamp desc
```

### easy-day-js typosquat installed in node_modules (setup.cjs + package.json drop)

`UC_13_7` · phase: **delivery** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats summariesonly=true count min(_time) as firstTime max(_time) as lastTime values(Filesystem.file_path) as path values(Filesystem.process_name) as proc from datamodel=Endpoint.Filesystem where (Filesystem.file_path="*\\node_modules\\easy-day-js\\*" OR Filesystem.file_path="*/node_modules/easy-day-js/*") AND Filesystem.action="created" by Filesystem.dest Filesystem.file_name
| `drop_dm_object_name(Filesystem)`
| convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
DeviceFileEvents
| where Timestamp > ago(30d)
| where ActionType in ("FileCreated","FileRenamed")
| where FolderPath has_any (@"\node_modules\easy-day-js\", "/node_modules/easy-day-js/")
| where FileName in~ ("setup.cjs","package.json","index.js")
| project Timestamp, DeviceName, ActionType, FolderPath, FileName, SHA256, FileSize,
          InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessAccountName
| order by Timestamp desc
```

### easy-day-js dropper writes .pkg_history / .pkg_logs beacon files in temp

`UC_13_8` · phase: **actions** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats summariesonly=true count min(_time) as firstTime max(_time) as lastTime values(Filesystem.file_path) as path values(Filesystem.process_name) as proc from datamodel=Endpoint.Filesystem where Filesystem.file_name IN (".pkg_history",".pkg_logs") AND Filesystem.action="created" by Filesystem.dest Filesystem.user Filesystem.file_name
| `drop_dm_object_name(Filesystem)`
| convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
DeviceFileEvents
| where Timestamp > ago(30d)
| where ActionType in ("FileCreated","FileModified")
| where FileName in (".pkg_history",".pkg_logs")
| where FolderPath has_any (@"\AppData\Local\Temp\", @"\Windows\Temp\", "/tmp/", "/var/folders/", "/private/var/folders/")
| project Timestamp, DeviceName, ActionType, FolderPath, FileName, FileSize, SHA256,
          InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessAccountName, InitiatingProcessParentFileName
| order by Timestamp desc
```

### easy-day-js dropper self-deletes setup.cjs from node_modules (forensic evasion)

`UC_13_9` · phase: **actions** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats summariesonly=true count min(_time) as firstTime max(_time) as lastTime values(Filesystem.file_path) as path values(Filesystem.process_name) as proc from datamodel=Endpoint.Filesystem where Filesystem.file_name="setup.cjs" AND Filesystem.action="deleted" AND (Filesystem.file_path="*\\node_modules\\easy-day-js\\*" OR Filesystem.file_path="*/node_modules/easy-day-js/*") by Filesystem.dest Filesystem.user
| `drop_dm_object_name(Filesystem)`
| convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
DeviceFileEvents
| where Timestamp > ago(30d)
| where ActionType == "FileDeleted"
| where FileName =~ "setup.cjs"
| where FolderPath has_any (@"\node_modules\easy-day-js\", "/node_modules/easy-day-js/")
| where InitiatingProcessFileName in~ ("node.exe","node")
| project Timestamp, DeviceName, ActionType, FolderPath, FileName,
          InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessId,
          InitiatingProcessParentFileName, InitiatingProcessAccountName
| order 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
```

### 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 — Mastra npm Supply Chain Attack: 140+ Packages Backdoored via easy-day-js Typosqu

`UC_13_4` · phase: **exploit** · confidence: **High**

**Splunk SPL (CIM):**
```spl
``` Article-specific bespoke detection — Mastra npm Supply Chain Attack: 140+ Packages Backdoored via easy-day-js Typosqu ```
| tstats `summariesonly` count earliest(_time) AS firstTime latest(_time) AS lastTime
    from datamodel=Endpoint.Processes
    where (Processes.process_name IN ("node.js"))
    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_name IN ("node.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 — Mastra npm Supply Chain Attack: 140+ Packages Backdoored via easy-day-js Typosqu
// 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"))
| 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 (FileName in~ ("node.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`


## Why this matters

Severity classified as **HIGH** based on: IOCs present, 10 use case(s) fired, 15 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.