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Plaintext Authentication

Caution: Using plaintext credentials is not recommended. Use encrypted authentication methods when possible.

If a secure method of performing credentialed checks is not available, users can force Nessus to try to perform checks over unsecure protocols; use the Plaintext Authentication options.

This menu allows the Nessus scanner to use credentials when testing HTTP, NNTP, FTP, POP2, POP3, IMAP, IPMI, SNMPv1/v2c, and telnet/rsh/rexec.

By supplying credentials, Nessus may have the ability to do more extensive checks to determine vulnerabilities. HTTP credentials supplied will be used for Basic and Digest authentication only.

Credentials for FTP, IPMI, NNTP, POP2, and POP3 require only a username and password.

HTTP

There are four different types of HTTP Authentication methods: Automatic authentication, Basic/Digest authentication, HTTP login form, and HTTP cookies import.

HTTP Global Settings

Option	Default	Description
Login method	POST	Specify if the login action is performed via a GET or POST request.
Re-authenticate delay (seconds)	0	The time delay between authentication attempts. This is useful to avoid triggering brute force lockout mechanisms.
Follow 30x redirections (# of levels)	0	If a 30x redirect code is received from a web server, this directs Nessus to follow the link provided or not.
Invert authenticated regex	Disabled	A regex pattern to look for on the login page, that if found, tells Nessus authentication was not successful (e.g., Authentication failed!).
Use authenticated regex on HTTP headers	Disabled	Rather than search the body of a response, Nessus can search the HTTP response headers for a given regex pattern to better determine authentication state.
Use authenticated regex on HTTP headers	Disabled	The regex searches are case sensitive by default. This instructs Nessus to ignore case.

Authentication methods

Automatic authentication

Username and Password Required

Basic/Digest authentication

Username and Password Required

HTTP Login Form

The HTTP login page settings provide control over where authenticated testing of a custom web-based application begins.

Option	Description
Username	Login user’s name.
Password	Password of the user specified.
Login page	The absolute path to the login page of the application, e.g., /login.html.
Login submission page	The action parameter for the form method. For example, the login form for <form method="POST" name="auth_form" action="/login.php"> would be /login.php.
Login parameters	Specify the authentication parameters (e.g., login=%USER%&password=%PASS%). If the keywords %USER% and %PASS% are used, they will be substituted with values supplied on the Login configurations drop-down box. This field can be used to provide more than two parameters if required (e.g., a group name or some other piece of information is required for the authentication process).
Check authentication on page	The absolute path of a protected web page that requires authentication, to better assist Nessus in determining authentication status, e.g., /admin.html.
Regex to verify successful authentication	A regex pattern to look for on the login page. Simply receiving a 200 response code is not always sufficient to determine session state. Nessus can attempt to match a given string such as Authentication successful!

HTTP cookies import

To facilitate web application testing, Nessus can import HTTP cookies from another piece of software (e.g., web browser, web proxy, etc.) with the HTTP cookies import settings. A cookie file can be uploaded so that Nessus uses the cookies when attempting to access a web application. The cookie file must be in Netscape format.

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