Input Validation / LMAP Injection



IMAP (Internet Message Access Protocol) Injection is a type of input validation vulnerability classified under CWE-20. It occurs when unfiltered user input is allowed to execute an IMAP command on an application-side IMAP server. This could occur if the application does not properly sanitize user input before passing it to the IMAP server. This vulnerability can be used to execute malicious commands on the IMAP server, allowing an attacker to gain unauthorized access to the server. It can also be used to bypass authentication and execute malicious commands. IMAP Injection is a high-level vulnerability and is described in the OWASP Testing Guide.


IMAP Injection can be used to gain unauthorized access to a server, bypass authentication, and execute malicious commands. If a server is vulnerable to IMAP Injection, an attacker can gain full control of the server, as well as access to sensitive information or files stored on the server. This can lead to data loss, data exfiltration, or malicious activity on the server. The risk of this vulnerability is high and should be addressed as soon as possible.


The best solution to IMAP Injection is to sanitize user input before passing it to the IMAP server. Input validation should be used to ensure that only valid input is accepted. This should be done by validating the input against a whitelist of valid characters and rejecting any input that contains invalid characters. Additionally, input should be encoded before passing it to the IMAP server. This will ensure that the input is not interpreted as an IMAP command.


The following code example shows how an attacker can exploit an IMAP Injection vulnerability to execute a malicious command:

GET /mail.php?user=foo&pass=bar&cmd=A%20SEARCH%20INBOX%20UNSEEN%20FROM%20%22%3C%3E%22%20

In the above example, the attacker has used the UNSEEN command to search for unseen messages from the empty string. This will retrieve all unseen messages in the INBOX folder.

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