CAPEC Details
Name Email Injection
Likelyhood of attack Typical severity
Low Medium
Summary An attacker manipulates the headers and content of an email message by injecting data via the use of delimiter characters native to the protocol. Many applications allow users to send email messages by filling in fields. For example, a web site may have a link to "share this site with a friend" where the user provides the recipient's email address and the web application fills out all the other fields, such as the subject and body. In this pattern, an attacker adds header and body information to an email message by injecting additional content in an input field used to construct a header of the mail message. This attack takes advantage of the fact that RFC 822 requires that headers in a mail message be separated by a carriage return. As a result, an attacker can inject new headers or content simply by adding a delimiting carriage return and then supplying the new heading and body information. This attack will not work if the user can only supply the message body since a carriage return in the body is treated as a normal character.
Prerequisites The target application must allow the user to send email to some recipient, to specify the content at least one header field in the message, and must fail to sanitize against the injection of command separators. The adversary must have the ability to access the target mail application.
Related Weaknesses
CWE ID Description
CWE-150 Improper Neutralization of Escape, Meta, or Control Sequences
Related CAPECS
CAPEC ID Description
CAPEC-137 An adversary manipulates the content of request parameters for the purpose of undermining the security of the target. Some parameter encodings use text characters as separators. For example, parameters in a HTTP GET message are encoded as name-value pairs separated by an ampersand (&). If an attacker can supply text strings that are used to fill in these parameters, then they can inject special characters used in the encoding scheme to add or modify parameters. For example, if user input is fed directly into an HTTP GET request and the user provides the value "myInput&new_param=myValue", then the input parameter is set to myInput, but a new parameter (new_param) is also added with a value of myValue. This can significantly change the meaning of the query that is processed by the server. Any encoding scheme where parameters are identified and separated by text characters is potentially vulnerable to this attack - the HTTP GET encoding used above is just one example.
Taxonomy: WASC
Entry ID Entry Name
30 Mail Command Injection