The purpose of this finding is to clarify the security concerns around using
passwords on the World Wide Web. Specifically, the objective is to point out
that passwords SHOULD NOT be transmitted in the clear except
in a few very specific cases.
Security on the World Wide Web is an important issue which needs to be
addressed or visible or publicized attacks on existing
vulnerabilities will create mistrust of the Web which
will limit its growth potential. Specifically this paper talks about the
use of passwords on the WWW and the needs to keep them secure during
display, temporary storage in cookies
as well as
The TAG feels there are sufficient technologies available to take a clear stance on password security as it relates to the World Wide Web.
This section addresses the issue of transmitting passwords in clear text over the World Wide Web. When a password is transmitted in clear text, it is vulnerable in many ways:
The HTTP spec specifically states that HTTP is not considered to be a secure method of user authentication (unless used in conjunction with some external secure systems such as SSL).
It is estimated that between 1 and 2 percent of e-commerce transactions are
related to fraud. As customers are
becoming more 'net savvy' hearing
more about web based attacks they are starting to examine web page types
and are attempting use only secure systems or to use
the systems they have securely. Therefore it's imperative that any
organization that wishes to safeguard its customers',
employees’ and users’ data start with secure transfers of
user login and password information.
Browsers can only follow good practice if they know
they are handling a password. Sites that do not use established protocols and
data conventions to signal the use of passwords to clients and browsers will
not benefit from this good practice.
There are some cases where it is acceptable to transmit
passwords in the clear; one example would be a test page that has no sensitive
information on it where the only reason for the prompting of the password is to
stop it from being indexed by a major search engine. Placing a password on the
page is a simple way to stop the crawling of the pages without really having to
'secure' the content. Because users often cannot tell when a password is being
send in the clear or not, we need another 'Good Practice' to make sure that
users are aware of the resulting vulnerability, and go on to use the same
password again for a application intended to be secure. Some sites attempt to reuse the notion of
passwords for other purposes, such as blocking indexing by search engines. Users
tend to choose the same password, or use the same algorithm for password
choice, and by and large have no reason to attempt to understand which
passwords are for security and which are for something else. It is a mis-use of
user generated passwords to use them for something else and to expose them on
the web. Only site generated and assigned passwords may be safely exposed, and
only if the user is clearly informed that password will not be protected by the
site that generated it.
While it's not the purpose of this paper to do an exhaustive description of secure transfer methods on the Web, there are a few common methods used today which are easy to implement;
Digest Access Authentication[Digest]:
Digest acts as an extension to HTTP 1.0 and offers a way for authentication to happen between parties using a 'shared secret' (a password). This verification method can be done without transmission of the password in clear text to address the HTTP 1.0 Basic method of authentication. The Digest method assumes that the username and password are prearranged. The requirement to prearrange usernames and passwords may complicate or prevent the user of Digest Authentication certain applications or contexts.
Secure Socket Layer (SSL/TLS)
SSL/TLS is a protocol developed for transmitting private channels via the Internet. SSL/TLS works by using a private key to encrypt data that's transferred over the SSL/TLS connection. Most browsers support SSL/TLS and most sites which require credit card information use SSL/TLS today. Originally developed by Netscape there are now many different authorities providing private keys. Self signed certificates may also be used to provide network confidentiality.
SOAP communicates over HTTP and is subject to similar password security concerns. While SSL/TSL can be used to secure SOAP-based messages point to point, the issue can be more complex if SOAP intermediaries are used. The TAG's position on SOAP remains consistent: that passwords and sensitive information MUST be transmitted in a secure manner and not as clear text. If confidential information is to be sent as part of the SOAP package, publishers SHOULD either use SSL/TLS or XML Encryption for sensitive data elements. Further information on security for SOAP messages can be found in Security Challenges, Threats and Countermeasures Version 1.0 [WSI] or on the OASIS Web Services Security TC home page[WSS].
HTML allows authors to create input forms for multiple purposes. It is the
TAG's opinion that if a form field is a password, password masking (or some other form of protection from physical proximity
capture) MUST take place to protect the user from onlookers seeing what
is being entered or later displayed
and stop anyone from later using the
'back' button to discover passwords.
If a password will not be protected in transit, protecting it in display may confuse a user about its sensitivity. [comment – I’d probably remove this entire recommendation myself, because the other two are so much more important, and this one is just slowing them down.]
[WSI]: Security Challenges, Threats and Countermeasures Version 1.0, WS-I. Available online as http://www.ws-i.org/Profiles/BasicSecurity/SecurityChallenges-1.0.pdf.