> 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/first-time-attachment-exchange.md).

# First-time attachment exchange

### Synopsis

| Field                | Value                                                              |
| -------------------- | ------------------------------------------------------------------ |
| Activation Period    | 14 Days                                                            |
| Training Period      | 30 Days                                                            |
| Test Period          | N/A (single event)                                                 |
| Deduplication Period | 1 Hour 30 Minutes                                                  |
| Required Data        | Microsoft 365 Emails                                               |
| Detection Modules    | Email                                                              |
| Detector Tags        | Phishing                                                           |
| ATT\&CK Tactic       | Execution (TA0002), Credential Access (TA0006)                     |
| ATT\&CK Technique    | User Execution (T1204), Brute Force: Password Cracking (T1110.002) |
| Severity             | Informational                                                      |

### Description

Detects when an attachment is sent between individuals for the first time in 30 days.

### Attacker's Goals

Trick the user on clicking the link or opening attachments, while avoiding detection.

### Investigative actions

* Examine the sender's IP address and reputation.
* Verify whether the sender's IP address has appeared in different log sources before, and if it is recognizable.
* Scrutinize the attachments for any suspicious indications or malicious content.
* Check if the attachments have been seen before in the organization.
* Monitor further actions taken, such as file downloads or execution of attachment content.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://cortex-docs.paloaltonetworks.com/analytics-alerts/alerts-by-name/first-time-attachment-exchange.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.