Information About Unmet Browser Exploit Requirements

Ah, I see your Metasploit has refused to serve your browser exploit to the target due to some kind of unmet requirements. This doesn't necessarily mean your target isn't vulnerable, sometimes it's just that it doesn't have the right conditions to be exploited. Or, it actually does mean the target isn't vulnerable. The following explains what each unmet requirement means:

• :source - Target has JavaScript disabled.
• :ua_name - Target isn't using the preferred browser. For example: Firefox, IE.
• :ua_ver - Target isn't using the preferred browser version.
• :os_name - Target isn't using the preferred operating system.
• :os_flavor - Target isn't using the preferred OS edition. For example: XP, Win 7.
• :language - Target isn't using the preferred OS language.
• :arch - Target isn't on the preferred architecture. For example: x86/x64
• :proxy - Target has a proxy.
• :silverlight - Target doesn't have Silverlight installed.
• :office - Target doesn't have the preferred version of Microsoft Office installed, so the exploit cannot bypass DEP.
• :java - Target doesn't have the preferred version of Java. Often this is used by exploits to bypass DEP.
• :clsid - Target doesn't have the preferred ActiveX control.
• :method - Target doesn't have the preferred ActiveX control.
• :mshtml_build - Target isn't on the preferred build of Internet Explorer. Usually means only specific builds of IE are vulnerable.
• :flash - Target isn't using the preferred version of Adobe Flash. Often this is used by exploits to leverage code execution.
• :vuln_test - A custom JavaScript-based check. See vuln_test_error for more info.

How to manually check requirement comparisons:

If you'd like to check the comparisons, simply set VERBOSE to true. The following is an example:

msf exploit(ms13_022_silverlight_script_object) > set VERBOSE true
VERBOSE => true
msf exploit(ms13_022_silverlight_script_object) > run
[*] Exploit running as background job.

[*] Started reverse handler on 192.168.1.64:4444 
[*] Using URL: http://0.0.0.0:8080/SHIzaS2aZxIA6
msf exploit(ms13_022_silverlight_script_object) >
[*]  Local IP: http://192.168.1.64:8080/SHIzaS2aZxIA6
[*] Server started.
[*] 192.168.1.80     ms13_022_silverlight_script_object - 192.168.1.80     ms13_022_silverlight_script_object - Received cookie 'sVfdquJGHzpHyLItxoTgeJI'.
[*] 192.168.1.80     ms13_022_silverlight_script_object - Gathering target information.
[*] 192.168.1.80     ms13_022_silverlight_script_object - Sending response HTML.
[*] 192.168.1.80     ms13_022_silverlight_script_object - 192.168.1.80     ms13_022_silverlight_script_object - Info receiver page called.
[*] 192.168.1.80     ms13_022_silverlight_script_object - 192.168.1.80     ms13_022_silverlight_script_object - Received cookie 'ZnKtXOQIvxAclSrEOxJ'.
[!] 192.168.1.80     ms13_022_silverlight_script_object - 192.168.1.80     ms13_022_silverlight_script_object - Received sniffed browser data over POST: 
{"os_name"=>["Microsoft Windows"], "os_flavor"=>["XP"], "ua_name"=>["MSIE"], "ua_ver"=>["8.0"], "arch"=>["x86"], "java"=>["null"], "silverlight"=>["false"], "flash"=>["null"], "office"=>["null"], "mshtml_build"=>["18702"]}.
[*] 192.168.1.80     ms13_022_silverlight_script_object - 192.168.1.80     ms13_022_silverlight_script_object - Received cookie 'ZnKtXOQIvxAclSrEOxJ'.
[*] 192.168.1.80     ms13_022_silverlight_script_object - 192.168.1.80     ms13_022_silverlight_script_object - Serving exploit to user with tag ZnKtXOQIvxAclSrEOxJ
[*] 192.168.1.80     ms13_022_silverlight_script_object - 192.168.1.80     ms13_022_silverlight_script_object - Setting target "ZnKtXOQIvxAclSrEOxJ" to :tried.
[!] 192.168.1.80     ms13_022_silverlight_script_object - 192.168.1.80     ms13_022_silverlight_script_object - Comparing requirement: source=(?i-mx:script|headers) vs k=script
[!] 192.168.1.80     ms13_022_silverlight_script_object - 192.168.1.80     ms13_022_silverlight_script_object - Comparing requirement: os_name=Microsoft Windows vs k=Microsoft Windows
[!] 192.168.1.80     ms13_022_silverlight_script_object - 192.168.1.80     ms13_022_silverlight_script_object - Comparing requirement: ua_name=MSIE vs k=MSIE
[!] 192.168.1.80     ms13_022_silverlight_script_object - 192.168.1.80     ms13_022_silverlight_script_object - Comparing requirement: silverlight=true vs k=false
[!] 192.168.1.80     ms13_022_silverlight_script_object - 192.168.1.80     ms13_022_silverlight_script_object - Comparing requirement: arch=x86 vs k=x86
[!] 192.168.1.80     ms13_022_silverlight_script_object - Exploit requirement(s) not met: silverlight

Related Reading:

https://github.com/rapid7/metasploit-framework/wiki/How-to-write-a-browser-exploit-using-BrowserExploitServer