# [HIGH] Gremlin Stealer's Evolved Tactics: Hiding in Plain Sight With Resource Files

**Source:** Unit 42 (Palo Alto)
**Published:** 2026-05-15
**Article:** https://unit42.paloaltonetworks.com/gremlin-stealer-evolution/

## Threat Profile

Threat Research Center 
Threat Research 
Malware 
Malware 
Gremlin Stealer's Evolved Tactics: Hiding in Plain Sight With Resource Files 
7 min read 
Related Products Advanced DNS Security Advanced Threat Prevention Advanced URL Filtering Advanced WildFire Cloud-Delivered Security Services Cortex Cortex XDR Cortex XSIAM Unit 42 Incident Response 
By: Pranay Kumar Chhaparwal 
Mark Lim 
Published: May 15, 2026 
Categories: Malware 
Threat Research 
Tags: API 
Cryptocurrency 
Gremlin stealer 
Obfusc…

## Indicators of Compromise (high-fidelity only)

- **IPv4 (defanged):** `194.87.92.109`
- **SHA256:** `2172dae9a5a695e00e0e4609e7db0207d8566d225f7e815fada246ae995c0f9b`

## MITRE ATT&CK Techniques

- **T1071.001** — Web Protocols
- **T1071.004** — DNS
- **T1071** — Application Layer Protocol
- **T1176** — Browser Extensions
- **T1539** — Steal Web Session Cookie
- **T1555.003** — Credentials from Web Browsers
- **T1566.002** — Spearphishing Link
- **T1204.001** — User Execution: Malicious Link
- **T1059.001** — PowerShell
- **T1204.004** — User Execution: Malicious Copy and Paste
- **T1027** — Obfuscated Files or Information
- **T1041** — Exfiltration Over C2 Channel
- **T1071.001** — Application Layer Protocol: Web Protocols
- **T1560.001** — Archive Collected Data: Archive via Utility
- **T1074.001** — Local Data Staging
- **T1204.002** — User Execution: Malicious File
- **T1027.002** — Obfuscated Files or Information: Software Packing
- **T1027.013** — Obfuscated Files or Information: Encrypted/Encoded File

## Kill chain phases observed

_(none detected from narrative keywords)_

## Recommended hunts

### Outbound connection to Gremlin Stealer exfiltration host 194.87.92.109

`UC_281_8` · phase: **actions** · confidence: **Medium** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats summariesonly=true count min(_time) as firstTime max(_time) as lastTime values(All_Traffic.src) as src values(All_Traffic.dest_port) as dest_port values(All_Traffic.app) as app from datamodel=Network_Traffic.All_Traffic where All_Traffic.dest="194.87.92.109" by All_Traffic.dest All_Traffic.src host | `drop_dm_object_name(All_Traffic)` | convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
let GremlinExfilIp = "194.87.92.109";
DeviceNetworkEvents
| where Timestamp > ago(30d)
| where RemoteIP == GremlinExfilIp
| project Timestamp, DeviceName, InitiatingProcessAccountName, InitiatingProcessFileName, InitiatingProcessFolderPath, InitiatingProcessCommandLine, RemoteIP, RemotePort, RemoteUrl, Protocol
| order by Timestamp asc
```

### ZIP archive named with public-IPv4 pattern created in user-writable directory (Gremlin Stealer)

`UC_281_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.user) as user values(Filesystem.process_name) as process_name from datamodel=Endpoint.Filesystem where Filesystem.action=created Filesystem.file_name="*.zip" (Filesystem.file_path="*\\AppData\\*" OR Filesystem.file_path="*\\Temp\\*" OR Filesystem.file_path="*\\Users\\*") by Filesystem.dest Filesystem.file_path Filesystem.file_name | `drop_dm_object_name(Filesystem)` | rex field=file_name "^(?<ipv4>\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})\.zip$" | where isnotnull(ipv4) | convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
DeviceFileEvents
| where Timestamp > ago(30d)
| where ActionType in ("FileCreated","FileRenamed")
| where FileName matches regex @"^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\.zip$"
| where FolderPath has_any (@"\AppData\", @"\Temp\", @"\Users\", @"\ProgramData\")
| where InitiatingProcessAccountName !endswith "$"
| project Timestamp, DeviceName, InitiatingProcessAccountName, InitiatingProcessFileName, InitiatingProcessFolderPath, InitiatingProcessCommandLine, FolderPath, FileName, SHA256, InitiatingProcessSHA256
| order by Timestamp asc
```

### Gremlin Stealer packed sample SHA256 execution (2172dae9a5a695e00e0e4609e7db0207d8566d225f7e815fada246ae995c0f9b)

`UC_281_10` · 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.user) as user values(Processes.parent_process_name) as parent values(Processes.process) as cmdline from datamodel=Endpoint.Processes where Processes.process_hash="2172dae9a5a695e00e0e4609e7db0207d8566d225f7e815fada246ae995c0f9b" by Processes.dest Processes.process_name Processes.process_hash | `drop_dm_object_name(Processes)` | convert ctime(firstTime) ctime(lastTime) | append [ | tstats summariesonly=true count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Filesystem where Filesystem.file_hash="2172dae9a5a695e00e0e4609e7db0207d8566d225f7e815fada246ae995c0f9b" by Filesystem.dest Filesystem.file_path Filesystem.file_name Filesystem.file_hash | `drop_dm_object_name(Filesystem)` | convert ctime(firstTime) ctime(lastTime) ]
```

**Defender KQL:**
```kql
let GremlinSha256 = "2172dae9a5a695e00e0e4609e7db0207d8566d225f7e815fada246ae995c0f9b";
union isfuzzy=true
  (DeviceProcessEvents
    | where Timestamp > ago(90d)
    | where SHA256 == GremlinSha256 or InitiatingProcessSHA256 == GremlinSha256
    | project Timestamp, _Source = "Process", DeviceName, AccountName, FileName, FolderPath, ProcessCommandLine, SHA256, InitiatingProcessFileName, InitiatingProcessSHA256),
  (DeviceFileEvents
    | where Timestamp > ago(90d)
    | where SHA256 == GremlinSha256
    | project Timestamp, _Source = "File", DeviceName, AccountName = InitiatingProcessAccountName, FileName, FolderPath, ProcessCommandLine = InitiatingProcessCommandLine, SHA256, InitiatingProcessFileName, InitiatingProcessSHA256)
| order by Timestamp asc
```

### 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
```

### Suspicious browser extension installation

`UC_BROWSER_EXT` · phase: **install** · confidence: **Medium**

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime
    from datamodel=Endpoint.Registry
    where (Registry.registry_path="*\Software\Google\Chrome\Extensions\*"
        OR Registry.registry_path="*\Software\Microsoft\Edge\Extensions\*"
        OR Registry.registry_path="*\Software\Mozilla\Firefox\Extensions\*")
    by Registry.dest, Registry.registry_path, Registry.registry_value_data, Registry.registry_value_name, Registry.user
| `drop_dm_object_name(Registry)`
```

**Defender KQL:**
```kql
DeviceRegistryEvents
| where Timestamp > ago(7d)
| where InitiatingProcessAccountName !endswith "$"
| where RegistryKey has_any ("\Software\Google\Chrome\Extensions\","\Software\Microsoft\Edge\Extensions\","\Software\Mozilla\Firefox\Extensions\")
| project Timestamp, DeviceName, RegistryKey, RegistryValueName, RegistryValueData,
          InitiatingProcessFileName, InitiatingProcessAccountName
```

### 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
```

### Phishing-link click correlated to endpoint execution

`UC_PHISH_LINK` · phase: **delivery** · confidence: **High**

**Splunk SPL (CIM):**
```spl
``` Phishing-link click that drives endpoint execution within 60s ```
| tstats `summariesonly` earliest(_time) AS click_time
    from datamodel=Web
    where Web.action="allowed"
    by Web.src, Web.user, Web.dest, Web.url
| `drop_dm_object_name(Web)`
| rename user AS recipient, dest AS clicked_domain, url AS clicked_url
| join type=inner recipient
    [| tstats `summariesonly` count
         from datamodel=Email.All_Email
         where All_Email.action="delivered" AND All_Email.url!="-"
         by All_Email.recipient, All_Email.src_user, All_Email.url, All_Email.subject
     | `drop_dm_object_name(All_Email)`
     | rex field=url "https?://(?<email_domain>[^/]+)"
     | rename recipient AS recipient]
| join type=inner src
    [| tstats `summariesonly` earliest(_time) AS exec_time
         values(Processes.process) AS exec_cmd, values(Processes.process_name) AS exec_proc
         from datamodel=Endpoint.Processes
         where Processes.parent_process_name IN ("chrome.exe","msedge.exe","firefox.exe",
                                                   "outlook.exe","brave.exe","arc.exe")
           AND Processes.process_name IN ("powershell.exe","pwsh.exe","cmd.exe","mshta.exe",
                                            "rundll32.exe","regsvr32.exe","wscript.exe",
                                            "cscript.exe","bitsadmin.exe","certutil.exe",
                                            "curl.exe","wget.exe")
         by Processes.dest, Processes.user
     | `drop_dm_object_name(Processes)`
     | rename dest AS src]
| eval delta_sec = exec_time - click_time
| where delta_sec >= 0 AND delta_sec <= 60
| table click_time, exec_time, delta_sec, recipient, src, src_user, subject,
        clicked_domain, clicked_url, exec_proc, exec_cmd
| sort - click_time
```

**Defender KQL:**
```kql
// Phishing-link click that drives endpoint execution within 60s.
// Far higher fidelity than "every clicked URL" — most legitimate clicks
// never spawn a non-browser child process, so the join eliminates the
// 99% of noise that makes a raw click query unactionable.
let LookbackDays = 7d;
let SuspectClicks = UrlClickEvents
    | where Timestamp > ago(LookbackDays)
    | where AccountName !endswith "$"
    | where ActionType in ("ClickAllowed","ClickedThrough")
    | join kind=inner (
        EmailEvents
        | where Timestamp > ago(LookbackDays)
        | where DeliveryAction == "Delivered"
        | where EmailDirection == "Inbound"
        | project NetworkMessageId, Subject, SenderFromAddress, SenderFromDomain,
                  RecipientEmailAddress, EmailTimestamp = Timestamp
      ) on NetworkMessageId
    | join kind=leftouter (
        EmailUrlInfo | project NetworkMessageId, Url, UrlDomain
      ) on NetworkMessageId, Url
    | project ClickTime = Timestamp, AccountUpn, IPAddress, Url, UrlDomain,
              Subject, SenderFromAddress, SenderFromDomain, RecipientEmailAddress,
              ActionType;
// Correlate to a non-browser child process spawned within 60 seconds on
// the recipient's device.
DeviceProcessEvents
| where Timestamp > ago(LookbackDays)
| where InitiatingProcessFileName in~ ("chrome.exe","msedge.exe","firefox.exe",
                                         "outlook.exe","brave.exe","arc.exe")
| where FileName in~ ("powershell.exe","pwsh.exe","cmd.exe","mshta.exe",
                        "rundll32.exe","regsvr32.exe","wscript.exe","cscript.exe",
                        "bitsadmin.exe","certutil.exe","curl.exe","wget.exe")
| join kind=inner SuspectClicks on $left.AccountName == $right.AccountUpn
| where Timestamp between (ClickTime .. ClickTime + 60s)
| project ClickTime, ProcessTime = Timestamp,
          DelaySec = datetime_diff('second', Timestamp, ClickTime),
          DeviceName, AccountName, RecipientEmailAddress, SenderFromAddress,
          Subject, Url, UrlDomain, ActionType,
          FileName, ProcessCommandLine, InitiatingProcessFileName
| order by ClickTime desc
```

### Fake CAPTCHA / clipboard-injected PowerShell (ClickFix / FakeCaptcha)

`UC_FAKECAPTCHA` · 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.parent_process_name IN ("explorer.exe","RuntimeBroker.exe")
      AND Processes.process_name IN ("powershell.exe","pwsh.exe","mshta.exe")
      AND (Processes.process="*iex*" OR Processes.process="*Invoke-Expression*"
        OR Processes.process="*FromBase64*" OR Processes.process="*DownloadString*"
        OR Processes.process="*hxxp*" OR Processes.process="*curl*" OR Processes.process="*wget*")
    by Processes.dest, Processes.user, Processes.process, Processes.parent_process_name
| `drop_dm_object_name(Processes)`
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(7d)
| where AccountName !endswith "$"
| where InitiatingProcessFileName in~ ("explorer.exe","RuntimeBroker.exe")
| where FileName in~ ("powershell.exe","pwsh.exe","mshta.exe")
| where ProcessCommandLine matches regex @"(?i)(iex|invoke-expression|frombase64|downloadstring|hxxp|curl |wget )"
| project Timestamp, DeviceName, AccountName, ProcessCommandLine, InitiatingProcessCommandLine
```

### 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
```

### 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): `194.87.92.109`

- **File hash IOCs — endpoint file/process match** ([template](../_TEMPLATES.md#hash-ioc)) — phase: **install**, confidence: **High**
  - file hash IOC(s): `2172dae9a5a695e00e0e4609e7db0207d8566d225f7e815fada246ae995c0f9b`


## Why this matters

Severity classified as **HIGH** based on: IOCs present, 11 use case(s) fired, 18 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.