Fix check method

Author: wvu

modules/exploits/linux/local/pkexec.rb

@@ -67,17 +67,21 @@ def executable_path
   end
 
   def check
-    version = cmd_exec('pkexec --version')
-    if version.nil?
-      print_error "Policykit is not installed"
-      return CheckCode::Safe
+    # version can be nil
+    version = cmd_exec('pkexec --version').split.last
+
+    # version can be a string, so we check it
+    if version.nil? || !Gem::Version.correct?(version)
+      vprint_error('pkexec not found or version incorrect')
+      return CheckCode::Unknown
     end
 
-    if Gem::Version.new(version.split('.')[1]) <= 0.101
+    if Gem::Version.new(version) <= Gem::Version.new('0.101')
+      vprint_good("pkexec #{version} found")
       return CheckCode::Appears
     end
 
-    CheckCode::Unknown
+    CheckCode::Safe
   end
 
   def exploit