mirror of
https://github.com/carlospolop/hacktricks
synced 2024-11-15 01:17:36 +00:00
174 lines
9.3 KiB
Markdown
174 lines
9.3 KiB
Markdown
# Email Injections
|
||
|
||
 (1) (2).png>)
|
||
|
||
\
|
||
Use [**Trickest**](https://trickest.com/?utm\_campaign=hacktrics\&utm\_medium=banner\&utm\_source=hacktricks) to easily build and **automate workflows** powered by the world's **most advanced** community tools.\
|
||
Get Access Today:
|
||
|
||
{% embed url="https://trickest.com/?utm_campaign=hacktrics&utm_medium=banner&utm_source=hacktricks" %}
|
||
|
||
<details>
|
||
|
||
<summary><strong>HackTricks in </strong><a href="https://twitter.com/carlospolopm"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch</strong></a> <strong>Wed - 18.30(UTC) 🎙️</strong> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>
|
||
|
||
* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
||
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
||
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
||
* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
|
||
* **Share your hacking tricks by submitting PRs to the** [**hacktricks repo**](https://github.com/carlospolop/hacktricks) **and** [**hacktricks-cloud repo**](https://github.com/carlospolop/hacktricks-cloud).
|
||
|
||
</details>
|
||
|
||
## Inject in sent e-mail 
|
||
|
||
### Inject Cc and Bcc after sender argument
|
||
|
||
```
|
||
From:sender@domain.com%0ACc:recipient@domain.co,%0ABcc:recipient1@domain.com
|
||
```
|
||
|
||
The message will be sent to the recipient and recipient1 accounts.
|
||
|
||
### Inject argument
|
||
|
||
```
|
||
From:sender@domain.com%0ATo:attacker@domain.com
|
||
```
|
||
|
||
The message will be sent to the original recipient and the attacker account.
|
||
|
||
### Inject Subject argument
|
||
|
||
```
|
||
From:sender@domain.com%0ASubject:This is%20Fake%20Subject
|
||
```
|
||
|
||
The fake subject will be added to the original subject and in some cases will replace it. It depends on the mail service behavior.
|
||
|
||
### Change the body of the message
|
||
|
||
Inject a two-line feed, then write your message to change the body of the message.
|
||
|
||
```
|
||
From:sender@domain.com%0A%0AMy%20New%20%0Fake%20Message.
|
||
```
|
||
|
||
### PHP mail() function exploitation
|
||
|
||
```bash
|
||
# The function has the following definition:
|
||
|
||
php --rf mail
|
||
|
||
Function [ <internal:standard> function mail ] {
|
||
- Parameters [5] {
|
||
Parameter #0 [ <required> $to ]
|
||
Parameter #1 [ <required> $subject ]
|
||
Parameter #2 [ <required> $message ]
|
||
Parameter #3 [ <optional> $additional_headers ]
|
||
Parameter #4 [ <optional> $additional_parameters ]
|
||
}
|
||
}
|
||
```
|
||
|
||
#### The 5th parameter ($additional\_parameters)
|
||
|
||
This section is going to be based on **how to abuse this parameter supposing that an attacker controls it**.
|
||
|
||
This parameter is going to be added to the command line PHP will be using to invoke the binary sendmail. However, it will be sanitised with the function `escapeshellcmd($additional_parameters)`.
|
||
|
||
An attacker can **inject extract parameters for sendmail** in this case.
|
||
|
||
#### Differences in the implementation of /usr/sbin/sendmail
|
||
|
||
**sendmail** interface is **provided by the MTA email software** (Sendmail, Postfix, Exim etc.) installed on the system. Although the **basic functionality** (such as -t -i -f parameters) remains the **same** for compatibility reasons, **other functions and parameters** vary greatly depending on the MTA installed.
|
||
|
||
Here are a few examples of different man pages of sendmail command/interface:
|
||
|
||
* Sendmail MTA: http://www.sendmail.org/\~ca/email/man/sendmail.html
|
||
* Postfix MTA: http://www.postfix.org/mailq.1.html
|
||
* Exim MTA: https://linux.die.net/man/8/eximReferences
|
||
|
||
Depending on the **origin of the sendmail** binary different options have been discovered to abuse them and l**eak files or even execute arbitrary commands**. Check how in [**https://exploitbox.io/paper/Pwning-PHP-Mail-Function-For-Fun-And-RCE.html**](https://exploitbox.io/paper/Pwning-PHP-Mail-Function-For-Fun-And-RCE.html)
|
||
|
||
## Inject in the e-mail name
|
||
|
||
### Ignored parts of an email
|
||
|
||
The symbols: **+, -** and **{}** in rare occasions can be used for tagging and ignored by most e-mail servers
|
||
|
||
* E.g. john.doe+intigriti@example.com → john.doe@example.com
|
||
|
||
**Comments between parentheses ()** at the beginning or the end will also be ignored
|
||
|
||
* E.g. john.doe(intigriti)@example.com → john.doe@example.com
|
||
|
||
### Whitelist bypass
|
||
|
||
<figure><img src="../.gitbook/assets/image (4) (6).png" alt=""><figcaption></figcaption></figure>
|
||
|
||
### Quotes
|
||
|
||
<figure><img src="../.gitbook/assets/image.png" alt=""><figcaption></figcaption></figure>
|
||
|
||
### IPs
|
||
|
||
You can also use IPs as domain named between square brackets:
|
||
|
||
* john.doe@\[127.0.0.1]
|
||
* john.doe@\[IPv6:2001:db8::1]
|
||
|
||
### Other vulns
|
||
|
||
.png>)
|
||
|
||
## Third party SSO
|
||
|
||
### XSS
|
||
|
||
Some services like **github** or **salesforce allows** you to create an **email address with XSS payloads on it**. If you can **use this providers to login on other services** and this services **aren't sanitising** correctly the email, you could cause **XSS**.
|
||
|
||
### Account-Takeover
|
||
|
||
If a **SSO service** allows you to **create an account without verifying the given email address** (like **salesforce**) and then you can use that account to **login in a different service** that **trusts** salesforce, you could access any account.\
|
||
_Note that salesforce indicates if the given email was or not verified but so the application should take into account this info._
|
||
|
||
## Reply-To
|
||
|
||
You can send an email using _**From: company.com**_\*\* \*\* and _**Replay-To: attacker.com**_ and if any **automatic reply** is sent due to the email was sent **from** an **internal address** the **attacker** may be able to **receive** that **response**.
|
||
|
||
## Hard Bounce Rate
|
||
|
||
Some applications like AWS have a **Hard Bounce Rate** (in AWS is 10%), that whenever is overloaded the email service is blocked.
|
||
|
||
A **hard bounce** is an **email** that couldn’t be delivered for some permanent reasons. Maybe the **email’s** a fake address, maybe the **email** domain isn’t a real domain, or maybe the **email** recipient’s server won’t accept **emails**) , that means from total of 1000 emails if 100 of them were fake or were invalid that caused all of them to bounce, **AWS SES** will block your service.
|
||
|
||
So, if you are able to **send mails (maybe invitations) from the web application to any email address, you could provoke this block by sending hundreds of invitations to nonexistent users and domains: Email service DoS.**
|
||
|
||
## References
|
||
|
||
* [https://resources.infosecinstitute.com/email-injection/](https://resources.infosecinstitute.com/email-injection/)
|
||
* [https://exploitbox.io/paper/Pwning-PHP-Mail-Function-For-Fun-And-RCE.html](https://exploitbox.io/paper/Pwning-PHP-Mail-Function-For-Fun-And-RCE.html)
|
||
* [https://drive.google.com/file/d/1iKL6wbp3yYwOmxEtAg1jEmuOf8RM8ty9/view](https://drive.google.com/file/d/1iKL6wbp3yYwOmxEtAg1jEmuOf8RM8ty9/view)
|
||
* [https://www.youtube.com/watch?app=desktop\&v=4ZsTKvfP1g0](https://www.youtube.com/watch?app=desktop\&v=4ZsTKvfP1g0)
|
||
|
||
<details>
|
||
|
||
<summary><strong>HackTricks in </strong><a href="https://twitter.com/carlospolopm"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch</strong></a> <strong>Wed - 18.30(UTC) 🎙️</strong> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>
|
||
|
||
* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
||
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
||
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
||
* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
|
||
* **Share your hacking tricks by submitting PRs to the** [**hacktricks repo**](https://github.com/carlospolop/hacktricks) **and** [**hacktricks-cloud repo**](https://github.com/carlospolop/hacktricks-cloud).
|
||
|
||
</details>
|
||
|
||
 (1) (2).png>)
|
||
|
||
\
|
||
Use [**Trickest**](https://trickest.com/?utm\_campaign=hacktrics\&utm\_medium=banner\&utm\_source=hacktricks) to easily build and **automate workflows** powered by the world's **most advanced** community tools.\
|
||
Get Access Today:
|
||
|
||
{% embed url="https://trickest.com/?utm_campaign=hacktrics&utm_medium=banner&utm_source=hacktricks" %}
|