Email injection is a
security vulnerability
Vulnerabilities are flaws in a computer system that weaken the overall security of the device/system. Vulnerabilities can be weaknesses in either the hardware itself, or the software that runs on the hardware. Vulnerabilities can be exploited by ...
that can occur in
Internet
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...
applications
Application may refer to:
Mathematics and computing
* Application software, computer software designed to help the user to perform specific tasks
** Application layer, an abstraction layer that specifies protocols and interface methods used in a c ...
that are used to send
email
Electronic mail (email or e-mail) is a method of exchanging messages ("mail") between people using electronic devices. Email was thus conceived as the electronic ( digital) version of, or counterpart to, mail, at a time when "mail" meant ...
messages. It is the email equivalent of
HTTP Header Injection. Like
SQL injection
In computing, SQL injection is a code injection technique used to attack data-driven applications, in which malicious SQL statements are inserted into an entry field for execution (e.g. to dump the database contents to the attacker). SQL inj ...
attacks, this vulnerability is one of a general class of vulnerabilities that occur when one
programming language
A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language.
The description of a programming ...
is embedded within another.
When a form is added to a
Web
Web most often refers to:
* Spider web, a silken structure created by the animal
* World Wide Web or the Web, an Internet-based hypertext system
Web, WEB, or the Web may also refer to:
Computing
* WEB, a literate programming system created by ...
page that submits data to a Web application, a malicious user may exploit the
MIME
Multipurpose Internet Mail Extensions (MIME) is an Internet standard that extends the format of email messages to support text in character sets other than ASCII, as well as attachments of audio, video, images, and application programs. Message ...
format to append additional information to the message being sent, such as a new list of recipients or a completely different message body. Because the MIME format uses a
carriage return
A carriage return, sometimes known as a cartridge return and often shortened to CR, or return, is a control character or mechanism used to reset a device's position to the beginning of a line of text. It is closely associated with the line feed a ...
to delimit the information in a message, and only the raw message determines its eventual destination, adding carriage returns to submitted form data can allow a simple guestbook to be used to send thousands of messages at once. A malicious
spammer
Spamming is the use of messaging systems to send multiple unsolicited messages (spam) to large numbers of recipients for the purpose of commercial advertising, for the purpose of non-commercial proselytizing, for any prohibited purpose (especial ...
could use this tactic to send large numbers of messages anonymously.
More information on this topic, including examples and ways to avoid the vulnerability, can be found at th
SecurePHP Wiki
However, this vulnerability is not limited to
PHP
PHP is a general-purpose scripting language geared toward web development. It was originally created by Danish-Canadian programmer Rasmus Lerdorf in 1993 and released in 1995. The PHP reference implementation is now produced by The PHP Group ...
; it can potentially affect ''any'' application that sends email messages based on input from arbitrary users.
References
External links
Email Headers Injection Using mail() Function(English)
Email Headers Injection Using mail() Function(French)
Injection exploits
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