# [CRIT] Threat Brief: Exploitation of PAN-OS Captive Portal Zero-Day for Unauthenticated Remote Code Execution

**Source:** Unit 42 (Palo Alto)
**Published:** 2026-05-07
**Article:** https://unit42.paloaltonetworks.com/captive-portal-zero-day/

## Threat Profile

Threat Research Center 
High Profile Threats 
Vulnerabilities 
Vulnerabilities 
Threat Brief: Exploitation of PAN-OS Captive Portal Zero-Day for Unauthenticated Remote Code Execution 
5 min read 
Related Products Advanced DNS Security Advanced Threat Prevention Advanced URL Filtering Advanced WildFire Cloud-Delivered Security Services Cortex Cortex Cloud Cortex Xpanse Next-Generation Firewall Unit 42 Incident Response 
By: Justin Moore 
Unit 42 
Published: May 6, 2026 
Categories: High Profile T…

## Indicators of Compromise (high-fidelity only)

- **CVE:** `CVE-2026-0300`
- **IPv4 (defanged):** `67.206.213.86`
- **IPv4 (defanged):** `136.0.8.48`
- **IPv4 (defanged):** `146.70.100.69`
- **IPv4 (defanged):** `149.104.66.84`
- **SHA256:** `e11f69b49b6f2e829454371c31ebf86893f82a042dae3f2faf63dcd84f97a584`

## MITRE ATT&CK Techniques

- **T1071.001** — Web Protocols
- **T1071.004** — DNS
- **T1071** — Application Layer Protocol
- **T1003.001** — LSASS Memory
- **T1003** — OS Credential Dumping
- **T1190** — Exploit Public-Facing Application
- **T1021.002** — SMB/Windows Admin Shares
- **T1569.002** — Service Execution
- **T1059.001** — PowerShell
- **T1027** — Obfuscated Files or Information
- **T1219** — Remote Access Software
- **T1204.002** — User Execution: Malicious File
- **T1105** — Ingress Tool Transfer
- **T1090.002** — External Proxy
- **T1572** — Protocol Tunneling
- **T1071.001** — Application Layer Protocols: Web
- **T1087.002** — Account Discovery: Domain Account
- **T1018** — Remote System Discovery
- **T1069.002** — Permission Groups Discovery: Domain Groups

## Kill chain phases observed

_(none detected from narrative keywords)_

## Recommended hunts

### CL-STA-1132 EarthWorm staging download from 146.70.100.69:8000/php_sess

`UC_325_9` · phase: **c2** · 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.dest_port) as dest_port values(All_Traffic.src) as src values(All_Traffic.app) as app from datamodel=Network_Traffic.All_Traffic where All_Traffic.dest in ("146.70.100.69","67.206.213.86","136.0.8.48","149.104.66.84") by All_Traffic.dest All_Traffic.src host | `drop_dm_object_name(All_Traffic)` | append [| tstats summariesonly=true count from datamodel=Web.Web where (Web.dest="146.70.100.69" AND Web.dest_port=8000 AND Web.url="*/php_sess*") OR Web.url="*Acebond/ReverseSocks5/releases*" by Web.src Web.dest Web.url Web.http_user_agent | `drop_dm_object_name(Web)`] | convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
let CampaignIPs = dynamic(["146.70.100.69","67.206.213.86","136.0.8.48","149.104.66.84"]);
DeviceNetworkEvents
| where Timestamp > ago(30d)
| where RemoteIP in (CampaignIPs)
   or (RemoteUrl has_any ("php_sess","Acebond/ReverseSocks5")
       and RemoteIPType == "Public")
| project Timestamp, DeviceName, DeviceId,
          InitiatingProcessFileName, InitiatingProcessCommandLine,
          InitiatingProcessAccountName, RemoteIP, RemotePort, RemoteUrl,
          ActionType, Protocol
| order by Timestamp desc
```

### Malformed CL-STA-1132 attacker User-Agent (Mozilla/5.5 + Safari/532.31)

`UC_325_10` · phase: **exploit** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats summariesonly=true count min(_time) as firstTime max(_time) as lastTime values(Web.url) as urls values(Web.dest) as dest values(Web.status) as status from datamodel=Web.Web where Web.http_user_agent="*Mozilla/5.5*" AND Web.http_user_agent="*Safari/532.31*" by Web.src Web.http_user_agent host | `drop_dm_object_name(Web)` | convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
// Defender XDR has limited HTTP User-Agent visibility outside DeviceNetworkEvents.AdditionalFields
// for HttpConnectionInspected actions; this is best-effort. Pivot to firewall logs in Sentinel for primary coverage.
DeviceNetworkEvents
| where Timestamp > ago(30d)
| where ActionType == "HttpConnectionInspected"
| extend UA = tostring(parse_json(AdditionalFields).user_agent)
| where UA has "Mozilla/5.5" and UA has "Safari/532.31"
| project Timestamp, DeviceName, RemoteIP, RemoteUrl, RemotePort, UA,
          InitiatingProcessFileName
```

### PAN-OS firewall service account LDAP enumeration of DomainDnsZones

`UC_325_11` · phase: **actions** · confidence: **Medium** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
`wineventlog_security` EventCode=4662 ObjectName="*DomainDnsZones*" OR ObjectName="*CN=Configuration*" OR ObjectName="*DC=*" 
| eval is_fw_account=if(match(SubjectUserName,"(?i)^(panos|panfw|pa-svc|paloalto|fw-svc|user-id).*"),1,0)
| stats min(_time) as firstTime max(_time) as lastTime count values(ObjectName) as objects values(IpAddress) as src_ip values(Computer) as dc by SubjectUserName SubjectDomainName is_fw_account
| where count > 5 OR is_fw_account=1
| convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
// Adjust the FirewallSvcAccounts list to your tenant's PAN-OS User-ID / LDAP bind accounts
let FirewallSvcAccounts = dynamic(["panos-svc","panfw","pa-userid","paloalto-bind","fw-svc"]);
let FirewallMgmtIPs   = dynamic([]);  // populate with PAN-OS management IPs
IdentityQueryEvents
| where Timestamp > ago(30d)
| where ActionType in ("LDAP query","LDAPQuery","SAMR query")
| where Query has_any ("DomainDnsZones","DC=DomainDnsZones","CN=MicrosoftDNS")
   or QueryTarget has "DomainDnsZones"
| extend AcctLower = tolower(AccountName)
| where AcctLower in (FirewallSvcAccounts)
   or IPAddress in (FirewallMgmtIPs)
   or AccountName has_any ("panos","panfw","paloalto","user-id")
| project Timestamp, AccountName, AccountDomain, AccountUpn,
          DeviceName, IPAddress, ActionType, Query, QueryTarget, Protocol
| 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
```

### LSASS process access / dump (credential theft)

`UC_LSASS` · 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="*lsass*" OR Processes.process="*sekurlsa*"
        OR Processes.process="*MiniDump*" OR Processes.process="*comsvcs.dll*MiniDump*"
        OR Processes.process="*procdump*lsass*")
       OR (Processes.process_name="rundll32.exe" AND Processes.process="*comsvcs*MiniDump*")
    by Processes.dest, Processes.user, Processes.process_name, Processes.process, Processes.parent_process_name
| `drop_dm_object_name(Processes)`
```

**Defender KQL:**
```kql
DeviceEvents
| where Timestamp > ago(7d)
| where AccountName !endswith "$"
| where ActionType == "OpenProcessApiCall"
| where FileName =~ "lsass.exe"
| where InitiatingProcessFileName !in~ ("MsSense.exe","MsMpEng.exe","csrss.exe",
                                          "svchost.exe","wininit.exe","services.exe",
                                          "lsm.exe","SearchProtocolHost.exe")
| project Timestamp, DeviceName, ActionType, FileName,
          InitiatingProcessFileName, InitiatingProcessCommandLine,
          InitiatingProcessFolderPath, AccountName
| order by Timestamp desc
```

### 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
```

### RMM tool installed by non-IT user — remote-access utility for hands-on-keyboard

`UC_RMM_TOOLS` · phase: **install** · 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 ("AnyDesk.exe","TeamViewer.exe","TeamViewer_Service.exe",
        "ScreenConnect.ClientService.exe","ConnectWiseControl.ClientService.exe",
        "atera_agent.exe","SplashtopStreamer.exe","RustDesk.exe","NinjaOne.exe","kaseya*.exe")
    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~ ("AnyDesk.exe","TeamViewer.exe","TeamViewer_Service.exe",
        "ScreenConnect.ClientService.exe","ConnectWiseControl.ClientService.exe",
        "atera_agent.exe","SplashtopStreamer.exe","RustDesk.exe","NinjaOne.exe")
   or FileName matches regex @"(?i)kaseya.*\.exe"
| project Timestamp, DeviceName, AccountName, FileName, ProcessCommandLine
```

### Article-specific behavioural hunt — Threat Brief: Exploitation of PAN-OS Captive Portal Zero-Day for Unauthenticated

`UC_325_8` · phase: **install** · confidence: **High**

**Splunk SPL (CIM):**
```spl
``` Article-specific bespoke detection — Threat Brief: Exploitation of PAN-OS Captive Portal Zero-Day for Unauthenticated ```
| tstats `summariesonly` count
    from datamodel=Endpoint.Filesystem
    where Filesystem.action IN ("created","modified")
      AND (Filesystem.file_path="*/var/tmp/linuxap*" OR Filesystem.file_path="*/var/tmp/linuxda*" OR Filesystem.file_path="*/var/tmp/linuxupdate*" OR Filesystem.file_path="*/tmp/.c*" OR Filesystem.file_path="*/tmp/R5*" OR Filesystem.file_path="*/var/R5*")
    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 — Threat Brief: Exploitation of PAN-OS Captive Portal Zero-Day for Unauthenticated
// Hunts the actual binaries / paths / commandline fragments named
// in the article instead of a generic technique-class template.

// File-creation events for the named binaries / paths
DeviceFileEvents
| where Timestamp > ago(30d)
| where ActionType in ("FileCreated","FileModified")
| where (FolderPath has_any ("/var/tmp/linuxap", "/var/tmp/linuxda", "/var/tmp/linuxupdate", "/tmp/.c", "/tmp/R5", "/var/R5"))
| 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): `67.206.213.86`, `136.0.8.48`, `146.70.100.69`, `149.104.66.84`

- **Asset exposure — vulnerability matches article CVE(s)** ([template](../_TEMPLATES.md#asset-exposure)) — phase: **recon**, confidence: **High**
  - CVE(s): `CVE-2026-0300`

- **File hash IOCs — endpoint file/process match** ([template](../_TEMPLATES.md#hash-ioc)) — phase: **install**, confidence: **High**
  - file hash IOC(s): `e11f69b49b6f2e829454371c31ebf86893f82a042dae3f2faf63dcd84f97a584`


## Why this matters

Severity classified as **CRIT** based on: CVE present, IOCs present, 12 use case(s) fired, 19 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.