TeamCity: use random padding bytes

Author: sjanusz-r7

lib/rex/proto/teamcity/rsa.rb

@@ -23,8 +23,7 @@ def self.pkcs1pad2(text, n)
 
     while n > 2
       n -= 1
-      # TODO: Random
-      r[n] = 0xff
+      r[n] = rand(1..255) # Can't be a null byte.
     end
 
     n -= 1