Email Injection Overview

Email injection is a security vulnerability that can occur in Internet applications that are used to send email messages. It arises when attackers are able to inject malicious code or commands into the message, which can lead to unauthorized access, data theft, or other malicious activities.

How Email Injection Works

Email injection attacks exploit poorly validated email headers submitted by users. When an application fails to validate or sanitize the headers, an attacker can introduce additional headers or entirely new email messages. This can be used to send spam, steal sensitive data, or conduct phishing attacks.

Risks of Email Injection

Email injection can lead to a variety of security risks, including:

• Spamming: Attackers can use the vulnerability to send spam emails from the compromised server.
• Phishing: Malicious actors can send phishing emails to trick users into revealing sensitive information.
• Data Theft: Attackers can exploit the vulnerability to access and steal sensitive data.
• Server Blacklisting: The compromised server can be blacklisted by email providers if it's detected sending spam.

Example of Email Injection Attack

An attacker can manipulate the input fields of a contact form to add additional headers. Here's a simple example:

john.doe@example.com%0ABcc: attacker@example.com

In the above code, `%0A` represents a newline character, which allows the attacker to add a new header, in this case, a Bcc header, causing the email to be sent to the attacker without the knowledge of the intended recipient.

Prevention Measures

To protect against email injection attacks:

1. Always validate and sanitize user inputs.
2. Use built-in functions or libraries that offer secure methods for sending emails.
3. Limit the length of email headers to prevent large injections.
4. Regularly update and patch software to fix known vulnerabilities.

Tools for Detecting Email Injection

Several tools can help detect and prevent email injection vulnerabilities:

• Acunetix: A web vulnerability scanner that can detect email injection vulnerabilities.
• OWASP ZAP: An open-source security tool for finding vulnerabilities in web applications.
• Wapiti: A web application vulnerability scanner that can identify email injection points.

Conclusion

Email injection attacks can have severe consequences for both businesses and their customers. By understanding the risks and implementing robust security measures, organizations can protect themselves from these threats.

Learn more about Email Injection from Invicti