> For the complete documentation index, see [llms.txt](https://cortex-docs.paloaltonetworks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cortex-docs.paloaltonetworks.com/analytics-alerts/alerts-by-name/abnormal-recurring-communications-to-a-rare-domain.md).
# Abnormal Recurring Communications to a Rare Domain
### Synopsis
| Field | Value |
| -------------------- | ------------------------------------------------------------------------------------------------------------------------------------ |
| Activation Period | 14 Days |
| Training Period | 30 Days |
| Test Period | N/A (single event) |
| Deduplication Period | 1 Day |
| Required Data | Requires one of the following data sources:
Palo Alto Networks Firewall traffic Logs OR XDR Agent OR Third-Party Firewalls
|
| Detector Tags | NDR C2 Detection |
| ATT\&CK Tactic | Command and Control (TA0011) |
| ATT\&CK Technique | Non-Application Layer Protocol (T1095) |
| Severity | Informational |
### Description
Abnormal communications were seen from an internal entity to a rare external domain. This could be a case of beaconing to a C2 Server.
### Attacker's Goals
Communicate with malicious code running on your network enabling further access to the endpoint and network, performing software updates on the endpoint, or for taking inventory of infected machines.
### Investigative actions
* Identify if the external domain belongs to a reputable organization or an asset used in a public cloud.
* Identify if the source of the traffic is malware. If the source of the traffic is a malicious file, Cortex XDR Analytics also raises a malware alert for the file on the endpoint. Malware may contact legitimate domain names, therefore check for unusual apps used or unusual ports or volumes accessed.
* View all related traffic generated by the suspicious process to understand the purpose.
* Look for other endpoints on your network that are also contacting the suspicious domain name.
* Examine file-system operations performed by the process that initiated the traffic and look for potential artifacts on infected endpoints.
### Variations
Abnormal Recurring Communications to a Rare Domain With a Port Commonly Used by Attack Platforms
**Synopsis**
| Field | Value |
| ----------------- | -------------------------------------- |
| ATT\&CK Tactic | Command and Control (TA0011) |
| ATT\&CK Technique | Non-Application Layer Protocol (T1095) |
| Severity | Low |
**Description**
Abnormal communications were seen from an internal entity to a rare external domain. This could be a case of beaconing to a C2 Server.
**Attacker's Goals**
Communicate with malicious code running on your network enabling further access to the endpoint and network, performing software updates on the endpoint, or for taking inventory of infected machines.
**Investigative actions**
* Identify if the external domain belongs to a reputable organization or an asset used in a public cloud.
* Identify if the source of the traffic is malware. If the source of the traffic is a malicious file, Cortex XDR Analytics also raises a malware alert for the file on the endpoint. Malware may contact legitimate domain names, therefore check for unusual apps used or unusual ports or volumes accessed.
* View all related traffic generated by the suspicious process to understand the purpose.
* Look for other endpoints on your network that are also contacting the suspicious domain name.
* Examine file-system operations performed by the process that initiated the traffic and look for potential artifacts on infected endpoints.
Abnormal Recurring Communications to a Rare Domain to a Suspicious Autonomous System (AS)
**Synopsis**
| Field | Value |
| ----------------- | -------------------------------------- |
| ATT\&CK Tactic | Command and Control (TA0011) |
| ATT\&CK Technique | Non-Application Layer Protocol (T1095) |
| Severity | Low |
**Description**
Abnormal communications were seen from an internal entity to a rare external domain. This could be a case of beaconing to a C2 Server.
**Attacker's Goals**
Communicate with malicious code running on your network enabling further access to the endpoint and network, performing software updates on the endpoint, or for taking inventory of infected machines.
**Investigative actions**
* Identify if the external domain belongs to a reputable organization or an asset used in a public cloud.
* Identify if the source of the traffic is malware. If the source of the traffic is a malicious file, Cortex XDR Analytics also raises a malware alert for the file on the endpoint. Malware may contact legitimate domain names, therefore check for unusual apps used or unusual ports or volumes accessed.
* View all related traffic generated by the suspicious process to understand the purpose.
* Look for other endpoints on your network that are also contacting the suspicious domain name.
* Examine file-system operations performed by the process that initiated the traffic and look for potential artifacts on infected endpoints.
Abnormal Recurring Communications to a Rare Domain With an Abnormal Domain Suffix
**Synopsis**
| Field | Value |
| ----------------- | -------------------------------------- |
| ATT\&CK Tactic | Command and Control (TA0011) |
| ATT\&CK Technique | Non-Application Layer Protocol (T1095) |
| Severity | Informational |
**Description**
Abnormal communications were seen from an internal entity to a rare external domain. This could be a case of beaconing to a C2 Server.
**Attacker's Goals**
Communicate with malicious code running on your network enabling further access to the endpoint and network, performing software updates on the endpoint, or for taking inventory of infected machines.
**Investigative actions**
* Identify if the external domain belongs to a reputable organization or an asset used in a public cloud.
* Identify if the source of the traffic is malware. If the source of the traffic is a malicious file, Cortex XDR Analytics also raises a malware alert for the file on the endpoint. Malware may contact legitimate domain names, therefore check for unusual apps used or unusual ports or volumes accessed.
* View all related traffic generated by the suspicious process to understand the purpose.
* Look for other endpoints on your network that are also contacting the suspicious domain name.
* Examine file-system operations performed by the process that initiated the traffic and look for potential artifacts on infected endpoints.
Abnormal Recurring Communications to a Rare Domain With a Less Common Port
**Synopsis**
| Field | Value |
| ----------------- | -------------------------------------- |
| ATT\&CK Tactic | Command and Control (TA0011) |
| ATT\&CK Technique | Non-Application Layer Protocol (T1095) |
| Severity | Low |
**Description**
Abnormal communications were seen from an internal entity to a rare external domain. This could be a case of beaconing to a C2 Server.
**Attacker's Goals**
Communicate with malicious code running on your network enabling further access to the endpoint and network, performing software updates on the endpoint, or for taking inventory of infected machines.
**Investigative actions**
* Identify if the external domain belongs to a reputable organization or an asset used in a public cloud.
* Identify if the source of the traffic is malware. If the source of the traffic is a malicious file, Cortex XDR Analytics also raises a malware alert for the file on the endpoint. Malware may contact legitimate domain names, therefore check for unusual apps used or unusual ports or volumes accessed.
* View all related traffic generated by the suspicious process to understand the purpose.
* Look for other endpoints on your network that are also contacting the suspicious domain name.
* Examine file-system operations performed by the process that initiated the traffic and look for potential artifacts on infected endpoints.
---
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