]> Nikto v2.1.5 - The Manual Introduction
Overview Nikto is a web server assessment tool. It is designed to find various default and insecure files, configurations and programs on any type of web server.
Description &description; The name "Nikto" is taken from the movie "The Day the Earth Stood Still", and of course subsequent abuse by Bruce Campbell in "Army of Darkness". More information on the pop-culture popularity of Nikto can be found at http://www.blather.net/blather/2005/10/klaatu_barada_nikto_the_day_th.html
Advanced Error Detection Logic Most web security tools, (including Nikto 1.32 and below), rely heavily on the HTTP response to determine if a page or script exists on the target. Because many servers do not properly adhere to RFC standards and return a 200 "OK" response for requests which are not found or forbidden, this can lead to many false-positives. In addition, error responses for various file extensions can differ--the "not found" response for a .html file is often different than a .cgi. Some testing tools, such as Nessus, also look at the content of the response to help eliminate these false positives. While often effective, this method relies on pre-defined strings to help eliminate false positives. As of version 2.0 Nikto no longer assumes the error pages for different file types will be the same. A list of unique file extensions is generated at run-time (from the test database), and each of those extensions is tested against the target. For every file type, the "best method" of determining errors is found: standard RFC response, content match or MD4 hash (in decreasing order of preference). This allows Nikto to use the fastest and most accurate method for each individual file type, and therefore help eliminate the false positives seen for some servers in version 1.32 and below. For example, if a server responds with a 404 "not found" error for a non-existent .txt file, Nikto will match the HTTP response of "404" on tests. If the server responds with a 200 "OK" response, it will try to match on the content, and assuming it finds a match (for example, the words "could not be found"), it will use this method for determining missing .txt files. If the other methods fail, Nikto will attempt to remove date and time strings (which can constantly change) from the returned page's content, generate an MD5 hash of the content, and then match that hash value against future .txt tests. The latter is by far the slowest type of match, but in many cases will provide valid results for a particular file type. This feature is performed by making several requests for non-existent pages of various filetypes. This may add up to a thousand requests to the remote server during the lifetime of the scan. This may not be desireable over slow connection and can be disabled with the -no404 option.
History The Nikto 1.00 Beta was released on December 27, 2001, (followed almost immediately by the 1.01 release). Over the course of two years Nikto's code evolved into the most popular freely available web vulnerability scanner. The 2.0 release, in November, 2007 represents several years of improvements. In 2008, David Lodge officially joined the development team and assumed leadership of Nikto while Chris Sullo pursued another committment. In 2009, Sullo rejoined the project.
Installation
Requirements Any system which supports a basic Perl installation should allow Nikto to run. It has been extensively tested on: Windows (using ActiveState Perl and Strawberry Perl). Some POSIX features, such as interactive commands may not work under Windows. Mac OSX Various Linux and Unix installations (including RedHat, Solaris, Debian, Ubuntu, BackTrack, etc.) The only required Perl module that does not come standard is LibWhisker. Nikto comes with and is configured to use a local LW.pm file (in the plugins directory). As of Nikto version 2.1.5, the included LibWhisker differs (slightly) from the standard LibWhisker 2.5 distribution. For SSL support the Net::SSLeay Perl module must be installed. Windows support for SSL is dependent on the installation package, but is rumored to exist for ActiveState's Perl. For support for logging to Metasploit, the RPC::XML and RPC::XML::Client modules must be installed. Nikto will operate with these modules, but the functionality will not be available. Perl: http://www.cpan.org/ LibWhisker: http://www.wiretrip.net/ ActiveState Perl: http://www.activestate.com/ OpenSSL: http://www.openssl.org/ Perl modules RPC::XML::Client and RPC::XML for Metasploit logging integration
Install These instructions do not include information on installing Perl, Perl Modules, OpenSSL, LibWhisker or any of the utilities that may be needed during installation (such as gzip, tar, etc.). Please see the distributor's documentation for information on how to install and configure those software packages. Unpack the download file: tar -xvfz nikto-current.tar.gz Assuming a standard OS/Perl installation, Nikto should now be usable. See Chapter 4 (Options) or Chapter 8 (Troubleshooting) for further configuration information.
Usage
Basic Testing The most basic Nikto scan requires simply a host to target, since port 80 is assumed if none is specified. The host can either be an IP or a hostname of a machine, and is specified using the -h (-host) option. This will scan the IP 192.168.0.1 on TCP port 80: perl nikto.pl -h 192.168.0.1 To check on a different port, specify the port number with the -p (-port) option. This will scan the IP 192.168.0.1 on TCP port 443: perl nikto.pl -h 192.168.0.1 -p 443 Hosts, ports and protocols may also be specified by using a full URL syntax, and it will be scanned: perl nikto.pl -h https://192.168.0.1:443/ There is no need to specify that port 443 may be SSL, as Nikto will first test regular HTTP and if that fails, HTTPS. If you are sure it is an SSL server, specifying -s (-ssl) will speed up the test. perl nikto.pl -h 192.168.0.1 -p 443 -ssl The -mutate and -mutate-options parameters have been deprecated in nikto 2.1.2. Plugin selections, using the -Plugin parameter, should be used instead. Nikto will automagically turn a mutate option into the appropriate selection string. More complex tests can be performed using the -mutate parameter, as detailed later. This can produce extra tests, some of which may be provided with extra parameters through the -mutate-options parameter. For example, using -mutate 3, with or without a file attempts to brute force usernames if the web server allows ~user URIs: perl nikto.pl -h 192.168.0.1 -mutate 3 -mutate-options user-list.txt
Multiple Port Testing Nikto can scan multiple ports in the same scanning session. To test more than one port on the same host, specify the list of ports in the -p (-port) option. Ports can be specified as a range (i.e., 80-90), or as a comma-delimited list, (i.e., 80,88,90). This will scan the host on ports 80, 88 and 443. perl nikto.pl -h 192.168.0.1 -p 80,88,443
Multiple Host Testing Nikto support scanning multiple hosts in the same session via a text file of host names or IPs. Instead of giving a host name or IP for the -h (-host) option, a file name can be given. A file of hosts must be formatted as one host per line, with the port number(s) at the end of each line. Ports can be separated from the host and other ports via a colon or a comma. If no port is specified, port 80 is assumed. This is an example of a valid hosts file: Valid Hosts File 192.168.0.1:80 http://192.168.0.1:8080/ 192.168.0.3 For win32 users: due to peculiaries in the way that cmd.exe works with pipes, the above example may not work for you. In this case a temporary file will have to be used to store the output from nmap A host file may also be an nmap output in "greppable" format (i.e. from the output from -oG). A file may be passed to Nikto through stdout/stdin using a "-" as the filename. For example: nmap -p80 192.168.0.0/24 -oG - | nikto.pl -h -
Using a Proxy If the machine running Nikto only has access to the target host (or update server) via an HTTP proxy, the test can still be performed. There are two ways to use a proxy with Nikto, via the nikto.conf file or directly on the command line. To use the nikto.conf file, set the PROXY* variables (as described in section 4), and then execute Nikto with the -useproxy option. All connections will be relayed through the HTTP proxy specified in the configuration file. perl nikto.pl -h localhost -p 80 -useproxy To set the proxy on the command line, use the -useproxy option with the proxy set as the argument, for example: ./nikto.pl -h localhost -useproxy http://localhost:8080/
Updating Nikto can be automatically updated, assuming you have Internet connectivity from the host Nikto is installed on. To update to the latest plugins and databases, simply run Nikto with the -update command. The -update option cannot be abbreviated. perl nikto.pl -update If updates are required, you will see a list of the files downloaded: perl nikto.pl -update + Retrieving 'nikto_core.plugin' + Retrieving 'CHANGES.txt' Updates may also be manually downloaded from the appropriate version's directory at http://cirt.net/nikto/UPDATES/. Plugin and database files from the server should replace those in the 'plugins' directory.
Integration with Nessus Nessus (http://www.nessus.org/nessus/) can be configured to automatically launch Nikto when it finds a web server. Ensure Nikto works properly, that nikto.pl is in the PATH, and that nikto.nasl is present in the Nessus install. Run 'nessusd -R' and then restart nessusd. See http://blog.tenablesecurity.com/2008/09/using-nessus-to.html for detailed instructions.
Interactive Features Nikto contains several options which can be changed during an active scan, provided it is running on a system which provides POSIX support, which includes *nix and some other operating systems. On systems without POSIX support, these features will be silently disabled. During an active scan, pressing any of the keys below will turn on or off the listed feature or perform the listed action. Note that these are case sensitive. SPACE - Report current scan status v - Turn verbose mode on/off d - Turn debug mode on/off e - Turn error reporting on/off p - Turn progress reporting on/off r - Turn redirect display on/off c - Turn cookie display on/off o - Turn OK display on/off a - Turn auth display on/off q - Quit N - Next host P - Pause
Command Line Options
All Options &options;
Mutation Techniques The -mutate and -mutate-options parameters have been deprecated in nikto 2.1.2. Plugin selections, using the -Plugin parameter, should be used instead. Nikto will automagically turn a mutate option into the appropriate selection string. A mutation will cause Nikto to combine tests or attempt to guess values. These techniques may cause a tremendous amount of tests to be launched against the target. Use the reference number to specify the type, multiple may be combined. Test all files with all root directories. This takes each test and splits it into a list of files and directories. A scan list is then created by combining each file with each directory. Guess for password file names. Takes a list of common password file names (such as "passwd", "pass", "password") and file extensions ("txt", "pwd", "bak", etc.) and builds a list of files to check for. Enumerate user names via Apache (/~user type requests). Exploit a misconfiguration with Apache UserDir setups which allows valid user names to be discovered. This will attempt to brute-force guess user names. A file of known users can also be supplied by supplying the file name in the -mutate-options parameter. Enumerate user names via cgiwrap (/cgi-bin/cgiwrap/~user type requests). Exploit a flaw in cgiwrap which allows valid user names to be discovered. This will attempt to brute-force guess user names. A file of known users can also be supplied by supplying the file name in the -mutate-options parameter. Attempt to brute force sub-domain names. This will attempt to brute force know domain names, it will assume the given host (without a www) is the parent domain. Attempt to brute directory names. This is the only mutate option that requires a file to be passed in the -mutate-options parameter. It will use the given file to attempt to guess directory names. Lists of common directories may be found in the OWASP DirBuster project.
Display By default only some basic information about the target and vulnerabilities is shown. Using the -Display parameter can produce more information for debugging issues. 1 - Show redirects. This will display all requests which elicit a "redirect" response from the server. 2 - Show cookies received. This will display all cookies that were sent by the remote host. 3 - Show all 200/OK responses. This will show all responses which elicit an "okay" (200) response from the server. This could be useful for debugging. 4 - Show URLs which require authentication. This will show all responses which elicit an "authorization required" header. D - Debug Output. Show debug output, which shows the verbose output and extra information such as variable content. E - Display all HTTP errors. Show details for any HTTP error encountered. P - Print progress to STDOUT. Show status report to STDOUT during testing (interval set in nikto.conf). V - Verbose Output. Show verbose output, which typically shows where Nikto is during program execution. E - Error Output. Display all HTTP and communications errors, which show a lot of output on some servers.
Scan Tuning Scan tuning can be used to decrease the number of tests performed against a target. By specifying the type of test to include or exclude, faster, focused testing can be completed. This is useful in situations where the presence of certain file types are undesired -- such as XSS or simply "interesting" files. Test types can be controlled at an individual level by specifying their identifier to the -T (-Tuning) option. In the default mode, if -T is invoked only the test type(s) specified will be executed. For example, only the tests for "Remote file retrieval" and "Command execution" can performed against the target: perl nikto.pl -h 192.168.0.1 -T 58 If an "x" is passed to -T then this will negate all tests of types following the x. This is useful where a test may check several different types of exploit. For example: perl nikto.pl -h 192.168.0.1 -T 58xb The valid tuning options are: 0 - File Upload. Exploits which allow a file to be uploaded to the target server. 1 - Interesting File / Seen in logs. An unknown but suspicious file or attack that has been seen in web server logs (note: if you have information regarding any of these attacks, please contact CIRT, Inc.). 2 - Misconfiguration / Default File. Default files or files which have been misconfigured in some manner. This could be documentation, or a resource which should be password protected. 3 - Information Disclosure. A resource which reveals information about the target. This could be a file system path or account name. 4 - Injection (XSS/Script/HTML). Any manner of injection, including cross site scripting (XSS) or content (HTML). This does not include command injection. 5 - Remote File Retrieval - Inside Web Root. Resource allows remote users to retrieve unauthorized files from within the web server's root directory. 6 - Denial of Service. Resource allows a denial of service against the target application, web server or host (note: no intentional DoS attacks are attempted). 7 - Remote File Retrieval - Server Wide. Resource allows remote users to retrieve unauthorized files from anywhere on the target. 8 - Command Execution / Remote Shell. Resource allows the user to execute a system command or spawn a remote shell. 9 - SQL Injection. Any type of attack which allows SQL to be executed against a database. a - Authentication Bypass. Allows client to access a resource it should not be allowed to access. b - Software Identification. Installed software or program could be positively identified. c - Remote source inclusion. Software allows remote inclusion of source code. x - Reverse Tuning Options. Perform exclusion of the specified tuning type instead of inclusion of the specified tuning type.
Single Request Mode Single request mode is designed to perform a solitary request against the target. This is useful to confirm a test result using the same resources Nikto used during a scan. The single option allows manual setting of most variables used by Nikto and LibWhisker, and upon completion will display both the request and the result of the operation. Most options have a default value or can be left blank. The most common and required values are at the beginning of the "questions" section for slightly easier use. True and false are specified by numeric equivalents, 1 and 0 respectively. Please note that Single mode is not very user-friendly. Here is an example Nikto run with the -Single option. [dave@yggdrasil nikto]$ ./nikto.pl -Single -------------------------------------------- Nikto 2.1.2 -------------------------------------------- Single Request Mode Hostname or IP: localhost Port (80): URI (/): /test.html SSL (0): Proxy host: Proxy port: Show HTML Response (1): HTTP Version (1.1): HTTP Method (GET): User-Agent (Mozilla/4.75 (Nikto/2.1.2): Connection (Keep-Alive): Data: force_bodysnatch (0): force_close (1): http_space1 ( ): http_space2 ( ): include_host_in_uri (0): invalid_protocol_return_value (1): max_size (0): protocol (HTTP): require_newline_after_headers (0): retry (0): ssl_save_info (0): timeout (10): uri_password (): uri_postfix (): uri_prefix (): uri_user (): Enable Encoding (0): -------------------------------------------- Done with questions Host Name: localhost Host IP: 127.0.0.1 HTTP Response Code: 404 -------------------------------------------- Connection Details Connection: Keep-Alive Host: localhost User-Agent: Mozilla/4.75 (Nikto/2.1.2) data: force_bodysnatch: 0 force_close: 1 force_open: 0 host: localhost http_space1: http_space2: ignore_duplicate_headers: 1 include_host_in_uri: 0 invalid_protocol_return_value: 1 max_size: 0 method: GET port: 80 protocol: HTTP require_newline_after_headers: 0 retry: 0 ssl: 0 ssl_save_info: 0 timeout: 10 trailing_slurp: 0 uri: /test.html uri_param_sep: ? uri_postfix: uri_prefix: version: 1.1 -------------------------------------------- Response Headers Connection: close Content-Length: 268 Content-Type: text/html; charset=iso-8859-1 Date: Tue, 18 Aug 2009 10:13:57 GMT Server: Apache/2 code: 404 http_data_sent: 1 http_eol: http_space1: http_space2: message: Not Found protocol: HTTP uri: /test.html version: 1.1 -------------------------------------------- Response Content <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"> <html><head> <title>404 Not Found</title> </head><body> <h1>Not Found</h1> <p>The requested URL /test.html was not found on this server.</p> <hr> <address>Apache/2 Server at localhost Port 80</address> </body></html>
Plugin selection From Nikto 2.1.2 plugins can be selected on an individual basis and may have parameters passed to them. A plugin selection string may be passed on the command line through the -Plugin parameter. It consists of a semi-colon separated list of plugin names with option parameters placed in brackets. In simple form a plugin statement is like:
plugin-name(parameter name:parameter value ,other parameters )
For example we can do: tests(report:500,verbose) Which will set the parameters report to a value of 500 and verbose to a value of 1. The parameters and plugin names can be found be running: ./nikto.pl -list-plugins This also means that we deprecate the mutate options and replace them with parameters passed to plugins, so the mutate options now internally translate to: tests(all) tests(passfiles) apacheusers(enumerate,home[,dictionary:dict.txt]) apacheusers(enumerate,cgiwrap[,dictionary:dict.txt]) subdomain dictionary(dictionary:dict.txt) Macros for commonly run plugin sets can also be defined in nikto.conf, the default ones are: @@MUTATE=dictionary;subdomain @@DEFAULT=@@ALL;-@@MUTATE;tests(report:500) These are expanded by using -list-plugins and can be overridden through -Plugins. Altogether this can allow a customised set of plugins that may need to be run for a specific circumstance. For example if a normal test bought up that the server was vulnerable to the apache Expect header XSS attack and we want to run a test just to see that it is vulnerable by adding debugging, we can run: nikto.pl -host target.txt -Plugins "apache_expect_xss(verbose,debug)" And then manually check the output to see whether it was truly vulnerable. It should be noted that reports are also plugins, so if you need to customize the plugin string and want an output, include the report plugin: nikto.pl -host targets.txt -Plugins "apacheusers(enumerate,dictionary:users.txt);report_xml" -output apacheusers.xml
Configuration Files
Location Nikto, like any non-trivial program needs to know a few things about how to work with the current environment. For most situations the default configuration file will work. Sometimes, tuning may be required, or some things may need to be changes. Nikto will look for a configuration file in three places and if it finds one, will apply it in the strict order, listed below. A later found configuration file will overwrite any variables set in an earlier configuration file. The locations are: /etc/nikto.conf (this may be altered depending on platform) $HOME/nikto.conf nikto.conf
Format The configuration files are formated like a standard Unix configuration file: blank lines are ignored, any line starting with a # is ignored, variables are set with VariableName=Value line.
Variables The following variables may be set within the configuration file: CLIOPTS Default options that should always be passed to the command line. For example: CLIOPTS=-output results.txt -Format text Default Setting CLIOPTS= NIKTODTD Path to the location of the DTD used for XML output. If the path is not absolute then it will be relative to the directory where Nikto is executed. Default Setting NIKTODTD=docs/nikto.dtd RFIURL Full URL to an file for remote file inclusion. This file should contain a call to phpinfo(), as Nikto will look for the output of that command to determine that the RFI succeeded. You may use the default cirt.net file, but please keep in mind there must be connectivity from the target server to cirt.net, it's subject to cirt.net's availability, and successful requests will be logged (by Apache). We recommend you use your own. Default Setting RFIURL=http://cirt.net/rfiinc.txt? SKIPPORTS This configuration item defines ports that would never be scanned by Nikto. Default Setting SKIPPORTS=21 111 SKIPIDS Note, this filter only applies to tests in the db_tests database Contains a space separated list of Test IDs (tids) that Nikto will not run on the system, for example: SKIPIDS=000045 000345 Default Setting SKIPIDS= DEFAULTHTTPVER Defines the default version of HTTP that Nikto will use, unless superceded by a specific test. Usually keeping this to the default will suffice, though some web servers may only work with later versions of the HTTP protocol. Default Setting DEFAULTHTTPVER=1.0 UPDATES If the outdated Nikto plugin sees a web server it doesn't know of, or a version that is later than that defined in db_outdated, then it will send this information back to cirt.net for inclusion in future versions of Nikto. Server specific information (e.g. IP addresses or hostnames) are not sent. This item can be set to one of the below values:
UPDATES=yes Display each submission and ask for permission before it is sent UPDATES=no Do not send any data back to cirt.net UPDATES=auto Send data back to cirt.net with no prompting
Default Setting UPDATES=yes LW_SSL_ENGINE Force LibWhisker to use the specified SSL library instead of the default select (Net::SSLeay, if available). This item can be set to one of the below values:
LW_SSL_ENGINE=auto use auto-selection LW_SSL_ENGINE=SSL use Net::SSL LW_SSL_ENGINE=SSLeay use Net::SSLeay
Default Setting LW_SSL_ENGINE=auto MAX_WARN Unused Produces a warning of a number of MOVED responses are retrieved. This is currently unused. Default Setting MAX_WARN=20 PROMPTS Disables Nikto prompts if set to "no". This is currently only used to prompt for proxy authentication and sending updates. Default Setting PROMPTS= CIRT The IP address that Nikto will use to update the databases and plugins, or will send version information back to (as described in the UPDATES item). Default Setting CIRT=174.142.17.165 PROXYHOST PROXYPORT PROXYUSER PROXYPASS Address, port and username password of a proxy to relay all requests through. Note, to use a proxy, you must set the configuration items in the configuration file and supply the -useproxy switch to the command line. Default Setting PROXYHOST= PROXYPORT= PROXYUSER= PROXYPASS= STATIC-COOKIE Adds the supplied cookie(s) to all requests made via Nikto. This is generally useful is an authentication cookie is required for a website. Separate cookies with a semi-colon, for example: STATIC-COOKIE="cookie1"="cookie value";"cookie2"="cookie val" Default Setting STATIC-COOKIE= CHECKMETHODS Nikto will attempt to identify targets as webservers by sending a request to fetch the / URI via certain HTTP methods. Some web servers do not implement all HTTP methods and may cause Nikto to fail to identify the web server correctly if it doesn't support the method being used. If this setting is missing from the configuration file, then Nikto will default back to the Nikto 2.02 default of HEAD. Default Setting CHECKMETHODS=HEAD GET EXECDIR PLUGINDIR TEMPLATEDIR DOCDIR Defines where to find the location of Nikto, its plugins, XML/HTML templates and documents. This should only normally be changed if repackaging Nikto to work with different file system standards. Nikto will use the EXECDIR item to guess the other directories. Default Setting EXECDIR=. PLUGINDIR=EXECDIR/plugins TEMPLATEDIR=EXECDIR/templates DOCDIR=EXECDIR/docs
Output and Reports
Export Formats Nikto allows output to be saved in a variety of formats, including text, CSV, HTML, XML, NBE and exporting to metasploit. When using -output, an output format may be specified with -Format. If no -Format is specified, Nikto will try to guess the format from the file extension. If Nikto cannot guess the file format then output will only be sent to stdout. The DTD for the Nikto XML format can be found in the 'docs' directory (nikto.dtd).
HTML and XML Customisation HTML reports are generated from template files located in the templates directory. Variables are defined as #variable-name, and are replaced when the report is generated. The files htm_start.tmpl and htm_end.tmpl are included at the beginning and end of the report (respectively). The htm_summary.tmpl also appears at the beginning of the report. The htm_host_head appears once for every host, and the htm_host_item.tmpl and htm_host_im.tmpl appear once for each item found on a host and each "informational message" per host (respectively). All valid variables are used in these templates. Future versions of this documentation will include a list of variables and their meaning. The copyright statements must not be removed from the htm_end.tmpl without placing them in another of the templates. It is a violation of the Nikto licence to remove these notices.
OSS Development
Open Source Contributions Nikto is an open source project licensed under the GNU GPL license. As such, code updates are welcomed and very much appreciated.
Development Source The Nikto development source code is located in a Subversion (SVN) repository which is publicly accessible. To download the source code, install Subversion and issue the following command: svn co http://svn2.assembla.com/svn/Nikto_2 For more information on the development enviornment, please see: http://www.assembla.com/spaces/Nikto_2/trac_subversion_tool
Test and Code Writing
Scan Database Field Values Though some checks can be found in other plugins, the db_tests contains the bulk of the web test information. Here is a description of the field values: Scan Database Fields Test ID Nikto test ID OSVDB-ID Corresponding vulnerability entry number for osvdb.org Server Type Generic server matching type URI URI to retrieve HTTP Method HTTP method to use for URI Match 1 String or code to match for successful test Match 1 (Or) String or code to alternatively match for successful test Match1 (And) String or code to also match for successful test Fail 1 String or code to match for test failure Fail 2 String or code to match for test failure (alternative) Summary Summary message to report for successful test HTTP Data HTTP data to be sent during POST tests Headers Additional headers to send during test
User-Defined Tests Users can create their own, private tests for any of the databases. By placing a syntactically correct database file in the plugins directory, with a file name prefaced with a "u", the data will be loaded along with the built-in checks. For example, create the file plugins/udb_tests and it will be loaded at the same time plugins/db_tests is loaded. These files will also be checked for syntax when -dbcheck is used. For tests which require a "private" OSVDB ID, use the OSVDB ID 0 (zero). This should be used for all vulnerabilities that do not (or should not) exist in OSVDB, as ID 0 is for testing only. You are encouraged to send missing information to OSVDB at moderators@osvdb.org. For the "Test ID", it is recommended you use unique numbers between 400000 and 499999 to allow for growth of the Nikto database without interfering with your own tests (note: numbers above 500000 are reserved for other tests). Please help Nikto's continued success by sending test updates to sullo@cirt.net.
Scan Database Syntax The scan database is a CSV delimited file which contains most of the tests. Fields are enclosed by quotes and separated by commas. The field order is: Test-ID, OSVDB-ID, Tuning Type, URI, HTTP Method, Match 1, Match 1 Or, Match1 And, Fail 1, Fail 2, Summary, HTTP Data, Headers Here is an example test: "120","3092","2","/manual/","GET","200","","","","","Web server manual","",""
Plugins Plugins allow other bits of code to hook into Nikto's processing and perform extra checks that cannot be achieved through the standard plugins. Plugins can use several hooks, these are:
Initialization (mandatory) Plugin initialization is performed before targets are assigned. During this phase, the plugin should tell Nikto about its existence and capabilities. It may optionally set up any later required variables. This is always called for every plugin, even if the plugin will not be used in the scan. Any database loading or variable setup should be deferred to the start hook. Start (optional) The start hook is called after target enumeration, but before target scanning occcurs, and will only be called on plugins that are scheduled to be run. It will only execute once. This hook is normally used to load databases or to initialize memory for the plugin. Reconnaisance (optional) During the reconnaisance phase, the plugin should look for interesting information that may be of use during the scan phase. It may report vulnerablities, though this is discouraged. Scan (optional) The scan phase should perform the meat of the plugin - this is where it should look at the web server and return any potential vulnerabilities. Reporting (optional) The reporting phase is used to export any found vulnerabilities into a format that they can be used later, for example written as a file report, or imported into a database. No testing of the web server, or reporting of new vulnerbilies should be performed in this phase. This phase is slightly more complex than the others and may be called at several points during Nikto's execution, as detailed later Prefetch (optional) The prefetch phase is called before every request to the server. It is passed a copy of the request hash and can amend it before it is sent to the server. This is normally used where standard data is needed for every request, for example, if authentication is needed. As this hook will be executed for every request made, for efficiency, the hook sub should be kept optimal. It is strongly advised that conditional execution (see below) is used to ensure that it is only run when needed. Postfetch (optional) The postfetch phase is called after every request to the server. It is passed a copy of the response hash, so that it can check for content or header specific risks. As this hook will be executed for every request made, for efficiency, the hook sub should be kept optimal. It is strongly advised that conditional execution (see below) is used to ensure that it is only run when needed.
Plugins are written in standard perl in the current context. They should be placed within the PLUGINDIR defined in the Nikto configuration file and must have a filename ending in .plugin. An important concept to grasp about plugins and the order that are executed in is plugin weight: each phase will execute all defined plugins in the order defined by the weight. A plugin's weight is defined as a number between 1 and 100, where 1 is high priority and 100 is low priority. Plugins of equal weight will be executed in an undefined order.
Initialization Phase As described above, all plugins must be able to execute in the initialisation phase or they will be ignored. A perl sub must exist called filename_init. The sub is passed no parameters and should return a hash reference to a hash that should contain the following entries: name (mandatory) The short name of the plugin. This is used to identify the plugin during verbose logging and will, in future versions, be used to select plugin execution. The name should be one word and, ideally, lower case. full_name (mandatory) The full name of the plugin. This is used to identify the plugin during verbose logging and may be used in reporting modules to identify tests run against the web server. author (mandatory) The name or handle of the author of the plugin. This may be used during reporting to identify ownerships of copyright of tests run against the web server. description (mandatory) A short sentence to describe the purpose of the plugin. This may be used during reporting, or by a front end to describe the purpose of the plugin. copyright (mandatory) The copyright string (or lack of it) of the plugin. This may be used during reporting to ensure that appropriate copyright is assigned to reports. hooks (optional) This should be a hash of hashes that contains information about the hooks that the plugin can respond to. Each key of the hooks element should be the name of the required hook with a hash value that details the information. The components of the hash should be: method (mandatory) This should be a reference to a function called for the hook. cond (optional) This is an expression to be evaluated before the plugin is executed; if true, the plugins is executed, if false, the plugin is skipped. This can be used to minimise plugin execution. weight (optional) This is the weight used to schedule the running of the plugin during the reconnaisance phase. If this is left undefined it will default to 50. options (optional) This is a hash that contains help information about any parameters that can be passed to the plugin. The information will be shown if the -list-plugins parameter is used. Each key of the options element should be the name of the parameter, with a value of a string providing a brief description of the parameter. report_head (optional) This should be a reference to a function executed before any testing commences. If this is left undefined then the plugin will not be called to produce a report header. report_host_start (optional) This should be a reference to a function executed before the reconnaisance phase of each host. If this is left undefined then the plugin will not be called to produce a host header. report_host_end (optional) This should be a reference to a function executed after the scan phase of each host. If this is left undefined then the plugin will not be called to produce a host footer. report_item (optional) This should be a reference to a function executed after each found vulnerability. If this is left undefined then the plugin will not be called to produce an item record. report_close (optional) This should be a reference to a function executed after testing of all hosts has been finished. If this is left undefined then the plugin will not be called to close the report. report_format (optional) This should describe the file format that the plugin handles. This is internally matched with the contents of the -output switch to reduce excessive calls to plugins. report_weight (optional) This is the weight used to schedule the running of the plugin during the reporting phase. If this is left undefined it will default to 50. Example initialisation function sub nikto_auth_init { my $id = { name => 'auth', full_name => 'Guess authentication', author => 'Sullo/Deity', description => 'Attempt to guess authentication realms', hooks => { start => { method => \&nikto_auth_load, weight => 1, }, postfetch => { method => \&nikto_auth, weight => 19, cond => '$result->{whisker}->{code} eq 401', }, prefetch => { method => \&nikto_auth_pre, weight => 19, }, }, copyright => "2010 CIRT Inc" }; return $id; }
Start hook The Start hook is called between target and enumeration and the start of scanning. It will only ever be called once, no matter how many targets Nikto is being run against. It will only be run against plugins that will be executed later. This makes it the ideal place to set up any required variables, assign variables or load databases for the plugin to be used in response to later hooks. The start method is passed no parameters and should return nothing. void start_method void
Reconnaisance Phase The reconnaisance phase is executed for each target at the start of each scan. Each reconnaisance method such expect to take a mark hash ref. It should return nothing. void recon_method hashref mark hashref parameters The reconnaisance phase is intended to be used to pull information about the web server for later use by the plugin, or by other plugins. Reporting vulnerabilities in this phase is discouraged. Example uses of the reconnaisance phase are to spider a site, check for known applications etc.
Scan Phase The scan phase is the meat of the plugin's life, this is run, for each target, immediately after the reconnaisance phase. Each scan should check for vulnerabilities it knows about and report on them as it finds one. void scan_method hashref mark hashref parameters
Prefetch hook The prefetch hook is executed before any request is made to the target. It is designed to allow the plugin to alter the libwhisker hash before the request. In normal execution, the prefetch hook should not report vulnerabilities. hashref request, hashref response prefetch_method hashref mark hashref parameters hashref request hashref result
Postfetch hook The postfetch hook is the executed after any request is made to the target. It is designed to allow the plugin to check for issues with the response, such as vulnerable headers or content. In normal execution, the postfetch hook should report any vulnerabilities that it finds. hashref request, hashref response postfetch_method hashref mark hashref parameters hashref request hashref result
Reporting Phase This is potentially the most convoluted phase as it has several hooks that may be used for each section in the scan's lifetime. The hooks are:
Report Head This hook is called immediately after target acquisition and before the reconnaisance phase. It is designed to allow the reporting plugin to open the report and ensure that any headers are appropiately written. handle report_head string filename The filename parameter is a bit of a misnomer; it will be a copy of the string passed to the -output switch and may indicate, for example, a database name. The handle is a handle that will be passed to other reporting functions for this plugin so should be internally consistent.
Report Host Start This hook is called immediately before the reconnaisance phase for each target. It is designed to allow the reporting plugin to write any host specfic information. void report_host_start handle rhandle hashref mark The rhandle parameter is the output of the plugin's Report Head function. The mark parameter is a hashref for the target information (described below).
Report Host End This hook is called immediately after the scan phase for each target. It is designed to allow the reporting plugin to close any host specfic information. void report_host_end handle rhandle hashref mark The rhandle parameter is the output of the plugin's Report Head function. The mark parameter is a hashref for the target information (described below).
Report Item This hook is called once for each vulnerability found on the target This should report details about the vulnerability. void report_item handle rhandle hashref mark hashref vulnerbility The rhandle parameter is the output of the plugin's Report Head function. The mark parameter is a hashref for the target information (described below). The vulnerability parameter is a hashref for the vulnerability information (described below).
Report Close This hook is called immediately after all targets have been scanned. It is designed to allow the reporting plugin to elegantly close the report. void report_close handle rhandle The rhandle parameter is the output of the plugin's Report Head function.
Data Structures The below data structures are used to communicate between the various plugin methods. Unless otherwise mentioned, they are all standard perl hash references with the detailed members.
<structname>Mark</structname> The mark hash contains all information about a target. It contains the below members. It should be read-only.
Members of the <structname>Mark</structname> structure ident Host identifier, usually equivalent to what was passed on the command line. hostname Host name of the target. ip IP address of the target. port TCP port of the target. display_name Either the hostname, or the IP address of the target, dependant on whether a hostname has been discovered. ssl Flag to indicate whether the target runs over SSL. If it is set to 0, then the plugin should not use SSL. Any other value indicates SSL should be used. vhost Virtual hostname to use for the target. root Root URI to use for the target. banner Banner of the target's web server.
Parameters The parameters hash contains all parameters that are passed directly to a plugin through one of the hooks. The hash has a key of the parameter name and a value of the passed parameter. Implementation and sanity checking of the values is left up to the plugin. If a parameter has not been set, it will not be in the hash. If it has been set to an undefined value, it will be set to the number 1 in the hash. Some parameters, such as verbose and debug will be automatically handled by the Nikto, though the parameters will still be included in the hash.
Vulnerability The vulnerability hash contains all information about a vulnerability. It contains the below members. It should be read-only and should only be written using the add_vulnerability method.
Members of the <structname>Vulnerability</structname> structure mark Hash ref to a mark data structure. message Message for the vulnerability. nikto_id Test ID (tid) of the vulnerability, this should be a unique number which'll identify the vulnerability. osvdb OSVDB reference to the vulnerability in the Open Source Vulnerability Database. This may be 0 if an OSVDB reference is not relevant or doesn't exist. method HTTP method used to find the vulnerability. uri URI for the result. result Any HTTP data, excluding headers.
Standard Methods Several standard methods are defined in nikto_core.plugin that can be used for all plugins. It is strongly advised that these should be used where possible instead of writing new methods. For some methods, such as add_vulnerability which write to global variables, these must be the only interface to those global variables. array change_variables string line Expands any variables in the line parameter. The expansions are variables defined in the global array @VARIABLES, which may be read from db_variables, or added by reconnaisance plugin methods. int is_404 string uri string content string HTTPcode Makes a guess whether the result is a real web page or an error page. As several web servers are badly configured and don't return HTTP 404 codes when a page isn't found, Nikto attempts to look for common error pages. Returns 1 if the page looks like an error. string get_ext string uri Attempts to work out the extension of the uri. Will return the extension or the special cases: DIRECTORY, DOTFILE, NONE. string date_disp void Returns the current time in a human readable format (YYYY-mm-dd hh:mm:ss) string rm_active string content Attempts to remove active content (e.g. dates, adverts etc.) from a page. Returns a filtered version of the content. string get_banner hashref mark Pulls the web servers banner. This is automatically performed for all targets before a mark is passed to the plugin. boolean content_present string HTTPcode Checks the HTTPresponse against known "found" responses. TRUE indicates that the request was probably successful. string HTTPCode, string content nfetch hashref mark string uri string method string content hashref headers hashref flags string testid Makes a simple request through libwhisker with the passed parameters. nfetch is hook aware and will cause all requests to be passed through the prefetch and postfetch hooks. The flags hash is a selection of flags that may modify the behaviour of the request. The current flags are defined:
Members of the <structname>flags</structname> structure noclean Tells nfetch not to perform sanity checks on the structure. Normally requests will be checked to ensure that a valid Host header is included and that the Content-Length header matches the size of any content, setting this flag prevents the checks nocache Tells nfetch to ignore the cache for this request, the page will not be checked against the cache or placed into the cache. noprefetch Tells nfetch not to run the prefetch hook. nopostfetch Tells nfetch not to run the postfetch hook. noerror Tells nfetch not to report error responses from the request.
hashref setup_hash hashref requesthash hashref mark Sets up up a libwhisker hash with the normal Nikto variables. This should be used if any custom calls to libwhisker are used. string char_escape string line Escapes any characters within line. array parse_csv string text Breaks a line of CSV text into an array of items. arrayref init_db string dbname Initializes a database that is in PLUGINDIR and returns an arrayref. The arrayref is to an array of hashrefs, each hash member is configured by the first line in the database file, for example: "nikto_id","md5hash","description" This will result in an array of hashrefs with parameters: array[0]->{nikto_id} array[0]->{md5hash} array[0]->{description} void add_vulnerability hashref mark string message string nikto_id string osvdb string method string uri string data Adds a vulnerability for the mark, displays it to standard out and sends it to any reporting plugins. void nprint string message string display Prints message to standard out. Display specifies a filter for the message, currently this can be "v" for verbose and "d" for debug output. void cache_add string method string response_code string content string uri string postdata integer nocache hashref mark Adds the page to Nikto's cache, creating a key from a hash of the passed data. This is normally handled by nfetch. The nocache is a mirror of the nocache flag sent to the nfetch function. integer incache, string response_code, string content cache_fetch string method string uri string postdata integer nocache hashref mark Fetches the contents of the page from Nikto's cache, the page being identified by the parameters. This is normally handled by nfetch. The nocache is a mirror of the nocache flag sent to the nfetch function.
Global Variables The following global variables exist within Nikto, most of them are defined for internal use and their use by plugins is not advised. Several have been deprecated, these should not be used by plugins. %TEMPLATES (read/write) Hash to store the HTML and XML report templates. %CONTENTSEARCH (read) Hash to contain all the entries in db_content_search - a list of strings and related info to alert on from any request (regardless of test result). %CLI (read) Hash of passed CLI parameters %VARIABLES (read) (write) Hash of contents of the entries in db_variables. Plugins should only write to this hash in the reconnaisance phase. %TESTS (read) (write) Hash of the db_tests database. This is only intended to be used by the tests plugin, though it could be used by a reconnaisance plugin to add tests on the fly. %NIKTO (read) Hash which contains internal Nikto data, such as help for the command line parameters. %CONFIGFILE (read) Hash containing the data read from the configuration files. %request (read) (write) (deprecated) %result (read) (write) (deprecated) Global libwhisker hash. This should not be used; nfetch or a local hash should be used. %COUNTERS (read) (write) Hash containing various global counters (e.g. number of requests) %db_extensions (read) (deprecated) Hash containing a list of common extensions %FoF (read) (write) Hash containing data for each extension and what the server produces if a request for a non-existent file is requested. %UPDATES (read) (write) Hash containing any updates that need to be sent back to cirt.net $DIV (read) Divider mark for the items sent to standard out. @DBFILE (read) Placeholder used to hold the contents of db_tests. $PROXYCHECKED (read) (deprecated) Flag to see whether connection through the proxy has been checked. @RESULTS (read) Array of reported vulnerabilities, should only be written to through add_vulnerability. @PLUGINS (read) Array of hashrefs for each plugin. Used internally to run plugins. @MARKS (read) Array of marks to indicate each target. @REPORTS (read) Ordered array that reporting plugins should be run in. Used for efficency on calling reporting plugins. %CACHE (read) (write) Containing the URI cache, should only be read/written through cache_add and cache_fetch.
Test Identifiers Each test, whether it comes from one of the databases or in code, must have a unique identifier. The numbering scheme for writing tests is as follows:
TID Scheme 000000 db_tests 400000 user defined tests (udb* files) 500000 db_favicon 600000 db_outdated 700000 db_realms 750000 db_content_search 800000 db_server_msgs 900000 tests defined in code
As much data as possible in the %TESTS hash should be populated for each new test that is defined in code (plugins). These fields include URI for the test, message to print on success, HTTP method and OSVDB ID. Without a 'message' value in %TESTS output will not be saved in HTML or XML reports. Not all tests are expected to have a uri, method or OSVDB ID. Here is an example of setting those fields: $TESTS{999999}{uri}="/~root"; $TESTS{999999}{message}="Enumeration of users is possible by requesting ~username"; $TESTS{999999}{method}="GET"; $TESTS{999999}{osvdb}=637;
Code Copyrights Any new or updated code, tests or information sent to the author is assumed to free of copyrights. By sending new or updated code, tests or information to the author you relinquish all claims of copyright on the material, and agree that this code can be claimed under the same copyright as Nikto.
Troubleshooting
SOCKS Proxies Nikto does not currently support SOCKS proxies.
Debugging The major route to debugging Nikto requests is to use the -Display with v (verbose) or d (debug). This will output a vast amount of extra information to the screen, so it is advised to redirect output to a file when using them.
Assistance If you need assistance with development or running Nikto, the Nikto-discuss mailing list can be an excellent resource and is an easy way to contact the developers and other knowledgeable users. For more information on the maling list, including archives and subscription options, please see http://cirt.net/nikto-discuss.
Licenses
Nikto Nikto is licensed under the GNU General Public License (GPL), and copyrighted by CIRT, Inc.
LibWhisker LibWhisker is licensed under the GNU General Public License (GPL), and Copyright (c) 2009, Jeff Forristal (wiretrip.net)
Tests The web tests are licensed for use with Nikto only, and may not be reused without written consent from CIRT, Inc.
Credits
Nikto Nikto is written and maintained by Chris Sullo and David Lodge. LibWhisker is written and maintained by Jeff Forristal (Rain Forrest Puppy).
Thanks Many people have provided feedback, fixes, and suggestions. This list is a feeble attempt to thank a few people, in no particular order: Nikto 2 Testing: Paul Woroshow, Mark G. Spencer, Michel Arboi, Jericho, rfp. Jericho (attrition.org/OSVDB/OSF). Support/ideas/tests/corrections/spam and help matching OSVDB IDs to tests. rfp (wiretrip.net). LibWhisker and continuing support. Erik Cabetas for many updates and fixes. Jake Kouns (OSVDB/OSF). Jabra (spl0it.org) for XML DTD, XML templates and supporting code. Stephen Valdez for extensive testing and being a great guy. S Saady. Extensive testing. P Eronen (nixu.com). Provided many code fixes. M Arboi. Great support by writing the code to make Nikto work within Nessus, as well as bug reports. J DePriest. Ideas/fixes. P Woroshow. Ideas/fixes. fr0stman. Tests. H Heimann. Tests. Xiola (xiola.net). Web design and more. Ryan Dewhurst. Domain guessing code. Frank Breedijk. NBE exporter code. Sussurro. MSF exporter code. Joe Hart, Gavin Jones, Ed Williams (Dyn_llandeilo). Lots of suggestions and bug finding. This document is © 2010 CIRT, Inc. and may not be reused without permission.