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https://github.com/carlospolop/hacktricks
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57 lines
2.6 KiB
Markdown
57 lines
2.6 KiB
Markdown
# Emails Vulnerabilities
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## Payloads
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### Ignored parts of an email
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The symbols: **+, -** and **{}** in rare occasions can be used for tagging and ignored by most e-mail servers
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* E.g. john.doe+intigriti@example.com → john.doe@example.com
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**Comments between parentheses ()** at the beginning or the end will also be ignored 
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* E.g. john.doe(intigriti)@example.com → john.doe@example.com
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### Whitelist bypass
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* inti(;inti@inti.io;)@whitelisted.com
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* inti@inti.io(@whitelisted.com)
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* inti+(@whitelisted.com;)@inti.io
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### IPs
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You can also use IPs as domain named between square brackets:
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* john.doe@\[127.0.0.1]
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* john.doe@\[IPv6:2001:db8::1]
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### Other vulns
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.png>)
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## Third party SSO
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### XSS
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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**.
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### Account-Takeover
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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.\
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_Note that salesforce indicates if the given email was or not verified but so the application should take into account this info._
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## Reply-To
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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**.
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## **References**
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* ****[**https://drive.google.com/file/d/1iKL6wbp3yYwOmxEtAg1jEmuOf8RM8ty9/view**](https://drive.google.com/file/d/1iKL6wbp3yYwOmxEtAg1jEmuOf8RM8ty9/view)****
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## Hard Bounce Rate
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Some applications like AWS have a **Hard Bounce Rate** (in AWS is 10%), that whenever is overloaded the email service is blocked.
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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.
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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.**
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