> 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/cortex-xdr-5.x/detect-investigate-and-respond-to-threats/threat-management/detection-rules/whats-an-ioc.md).

# What's an IOC?

Learn how indicators of compromise identify known threats.

**What's an IOC?**

{% hint style="info" %}

### Notice

Managing IOCs requires a Cortex XDR Pro license.
{% endhint %}

Indicators of compromise (IOCs) enable Cortex XDR to generate issues about known malicious objects on endpoints across the organization. You can load collections of IOCs from threat-intelligence sources into Cortex XDR or define them individually.

{% hint style="info" %}

### Note

Cortex XDR supports a maximum of 4,000,000 IOCs.
{% endhint %}

You can define the following types of IOCs:

* Full path
* File name
* Domain
* Destination IP address
* MD5 hash
* SHA256 hash

After you load or define IOCs, the tenant checks for matches in the xdr\_data dataset that contains all the information collected about the endpoints and the network. Cortex XDR looks for IOC matches in all data collected in the past and continues to evaluate any new data it receives in the future.

Issues for IOCs are identified by the source type of the IOC.


---

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