Nmap http-shellshock NSE Script


This page contains detailed information about how to use the http-shellshock NSE script. For list of all NSE scripts, visit the Nmap NSE Library.

Script Overview

Script source code: https://github.com/nmap/nmap/tree/master/scripts/http-shellshock.nse
Script categories: exploit, vuln, intrusive
Target service / protocol: http, https
Target network port(s): 80, 443, 631, 7080, 8080, 8443, 8088, 5800, 3872, 8180, 8000
List of CVEs: CVE-2014-6271, CVE-2014-7169

Script Description

The http-shellshock.nse script attempts to exploit the "shellshock" vulnerability (CVE-2014-6271 and CVE-2014-7169) in web applications.

To detect this vulnerability the script executes a command that prints a random string and then attempts to find it inside the response body. Web apps that don't print back information won't be detected with this method.

By default the script injects the payload in the HTTP headers User-Agent, Cookie, and Referer.

Vulnerability originally discovered by Stephane Chazelas.

References:

Http-shellshock NSE Script Arguments

This is a full list of arguments supported by the http-shellshock.nse script:

http-shellshock.cmd

Custom command to send inside payload. Default: nil

http-shellshock.header

HTTP header to use in requests. Default: User-Agent

http-shellshock.uri

URI. Default: /

smbdomain

The domain to log in with. If you aren't in a domain environment, then anything will (should?) be accepted by the server.

smbhash

A password hash to use when logging in. This is given as a single hex string (32 characters) or a pair of hex strings (both 32 characters, optionally separated by a single character). These hashes are the LanMan or NTLM hash of the user's password, and are stored on disk or in memory. They can be retrieved from memory using the fgdump or pwdump tools.

smbnoguest

Use to disable usage of the 'guest' account.

smbpassword

The password to connect with. Be cautious with this, since some servers will lock accounts if the incorrect password is given. Although it's rare that the Administrator account can be locked out, in the off chance that it can, you could get yourself in trouble. To use a blank password, leave this parameter off altogether.

smbtype

The type of SMB authentication to use. These are the possible options:

  • v1: Sends LMv1 and NTLMv1.
  • LMv1: Sends LMv1 only.
  • NTLMv1: Sends NTLMv1 only (default).
  • v2: Sends LMv2 and NTLMv2.
  • LMv2: Sends LMv2 only.
  • NTLMv2: Doesn't exist; the protocol doesn't support NTLMv2 alone. The default, NTLMv1, is a pretty decent compromise between security and compatibility. If you are paranoid, you might want to use v2 or lmv2 for this. (Actually, if you're paranoid, you should be avoiding this protocol altogether!). If you're using an extremely old system, you might need to set this to v1 or lm, which are less secure but more compatible. For information, see smbauth.lua.

smbusername

The SMB username to log in with. The forms "DOMAIN\username" and "username@DOMAIN" are not understood. To set a domain, use the smbdomain argument.

slaxml.debug

Debug level at which default callbacks will print detailed parsing info. Default: 3

http.host

The value to use in the Host header of all requests unless otherwise set. By default, the Host header uses the output of stdnse.get_hostname().

http.max-body-size

Limit the received body to specific number of bytes. An oversized body results in an error unless script argument http.truncated-ok or request option truncated_ok is set to true. The default is 2097152 (2MB). Use value -1 to disable the limit altogether. This argument can be overridden case-by-case with request option max_body_size.

http.max-cache-size

The maximum memory size (in bytes) of the cache.

http.max-pipeline

If set, it represents the number of outstanding HTTP requests that should be sent together in a single burst. Defaults to http.pipeline (if set), or to what function get_pipeline_limit returns.

http.pipeline

If set, it represents the number of HTTP requests that'll be sent on one connection. This can be set low to make debugging easier, or it can be set high to test how a server reacts (its chosen max is ignored).

http.truncated-ok

Do not treat oversized body as error. (Use response object flag truncated to check if the returned body has been truncated.) This argument can be overridden case-by-case with request option truncated_ok.

http.useragent

The value of the User-Agent header field sent with requests. By default it is "Mozilla/5.0 (compatible; Nmap Scripting Engine; https://nmap.org/book/nse.html)". A value of the empty string disables sending the User-Agent header field.

vulns.short

If set, vulnerabilities will be output in short format, a single line consisting of the host's target name or IP, the state, and either the CVE ID or the title of the vulnerability. Does not affect XML output.

vulns.showall

If set, the library will show and report all the registered vulnerabilities which includes the NOT VULNERABLE ones. By default the library will only report the VULNERABLE entries: VULNERABLE, LIKELY VULNERABLE, VULNERABLE (DoS) and VULNERABLE (Exploitable). This argument affects the following functions: vulns.Report.make_output(): the default output function for portule/hostrule scripts. vulns.make_output(): the default output function for postrule scripts. vulns.format_vuln() and vulns.format_vuln_table() functions.

- - -
To use these script arguments, add them to the Nmap command line using the --script-args arg1=value,[arg2=value,..] syntax. For example:

nmap --script=http-shellshock --script-args http-shellshock.cmd=value,http-shellshock.header=value <target>

Http-shellshock NSE Script Example Usage

Here's an example of how to use the http-shellshock.nse script:

nmap -sV -p- --script http-shellshock <target>

nmap -sV -p- --script http-shellshock --script-args uri=/cgi-bin/bin,cmd=ls <target>

Http-shellshock NSE Script Example Output

Here's a sample output from the http-shellshock.nse script:

PORT   STATE SERVICE REASON
80/tcp open  http    syn-ack
| http-shellshock:
|   VULNERABLE:
|   HTTP Shellshock vulnerability
|     State: VULNERABLE (Exploitable)
|     IDs:  CVE:CVE-2014-6271
|       This web application might be affected by the vulnerability known as Shellshock. It seems the server
|       is executing commands injected via malicious HTTP headers.
|
|     Disclosure date: 2014-09-24
|     References:
|       http://www.openwall.com/lists/oss-security/2014/09/24/10
|       https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-7169
|       http://seclists.org/oss-sec/2014/q3/685
|_      http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-6271

Http-shellshock NSE Script Example XML Output

Here's a sample XML output from the http-shellshock.nse script produced by providing the -oX <file> Nmap option:

 <elem key="title">HTTP Shellshock vulnerability</elem>
 <elem key="state">VULNERABLE (Exploitable)</elem>
 <table key="ids">
 <elem>CVE:CVE-2014-6271</elem>
 </table>
 <table key="description">
 <elem>This web application might be affected by the vulnerability known as Shellshock. It seems the server
 &#xa;is executing commands injected via malicious HTTP headers. &#xa;      </elem>
 </table>
 <table key="dates">
 <table key="disclosure">
 <elem key="year">2014</elem>
 <elem key="day">24</elem>
 <elem key="month">09</elem>
 </table>
 </table>
 <elem key="disclosure">2014-09-24</elem>
 <table key="refs">
 <elem>https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-7169</elem>
 <elem>http://www.openwall.com/lists/oss-security/2014/09/24/10</elem>
 <elem>http://seclists.org/oss-sec/2014/q3/685</elem>
 <elem>http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-6271</elem>
 </table>

Authors

  • Paulino Calderon <calderon()websec.mx
  • Paul Amar <paul()sensepost com>

References

See Also

Visit Nmap NSE Library for more scripts.

Version

This page has been created based on Nmap version 7.92.