This is where we can exploit the vulnerability to execute system commands with system privileges. The console uses the lua scripting language which is an embeddable scripting language that can be found in many software programs. When you type the ‘help’ command on the console you will be presented with a list of commands that you can use to control the Wing FTP server. You will also notice that executing system commands is not one of the options. Let’s have a look at how to execute the system commands manually. The vulnerability description mentions that we can execute system commands using the os.execute() function. Let’s try to use this function to create a new user named hacker on the Windows system and add it to the local administrator group. Use the following commands on the lua command line to add a user named ‘hacker’ with password ‘hacker’: #Wing ftp server windows# Root shell on the target host by exploiting Wing FTP Server 4.3.8 Os.execute(‘cmd.exe /c net localgroup administrators hacker /add’) Then add it to the local administrator group with the following command: Os.execute(‘cmd.exe /c net user hacker hacker /add’) #Wing ftp server password# Also check your backgrounded sessions after each attempt with the following command: Please note that sometimes you will not directly get a shell and you have to run the exploit again. The developers of Wing FTP server are actively maintaining the software and improving security. Your custom rule sids should be 1000000 or above, anything below this is reserved for the snort distribution rules.The authenticated command execution vulnerability has been fixed in versions later than 4.3.8 and updating to a later version will fix this issue. Having this in the rule will no prevent the rule from triggering if you aren't using target based, so it's also a good practice to put this in if you know the service this traffic is. If you are using target based (which now a days you should be), you need to add the service http keyword. This is going to be in the client body, so add the http_client_body option. Since this is the only content match in the rule that is case sensitive snort would put this into the fast pattern matcher on it's own, but if you modify the rule later on with another content match you would want this to be the content match to use for the fast_pattern matcher.Ĭontent:"command=os.execute" http_client_body nocase You know this content is static and never changing (case included) so this is eligible for the fast pattern matcher. You want nocase for the post match because it is not required by http for the method to be all capital letters.Ĭontent:"/admin_lua_script.html" fast_pattern http_uri Īdding the fast_pattern option will make the rule more efficient as it will put it into the fast pattern matcher in snort. The only way the request would be successful would be if the connection was already established between client and server, if it's not the exploit won't succeed and it's pointless to alert on this. This will be more efficient as snort won't have to check random traffic for unestablished sessions and it won't have to check traffic going to the client, since you know the direction for this exploit will always be going to the server. You only want to check established sessions where the flow is going to the server. If you do not have this port in your preprocessor config for http, all of your http content modifiers will NOT match because snort will not treat traffic on this port as http, which is likely the main issue you're having. ![]() (obviously don't put the dots, just representing other ports you should have in there). Preprocessor http_inspect_server: server default profile all ports Specifically, your nf should have a configuration line similar to the following: Important: Since this exploit module runs over port 5466 and is http you NEED to make sure that this port is in your http preprocessor configuration for ports. When you have rules that are "any/any" for source/destination snort treats them differently than rules with ports defined. You should always specify a port when possible. ![]() (msg:"FTP command execution" flow:to_server,established /Ĭontent:"/admin_lua_script.html" fast_pattern http_uri /Ĭontent:"command=os.execute" http_client_body nocase / I would recommend something like the following: alert tcp any any -> any 5466 /
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