fix(mssql): check if output isnt an empty list/None before trying to stringify it for output

Author: Marshall-Hallenbeck

nxc/protocols/mssql.py

@@ -318,9 +318,10 @@ def execute(self, payload=None, get_output=False):
             return False
         else:
             self.logger.success("Executed command via mssqlexec")   
-            output_lines = StringIO(output).readlines()
-            for line in output_lines:
-                self.logger.highlight(line.strip())
+            if output:
+                output_lines = StringIO(output).readlines()
+                for line in output_lines:
+                    self.logger.highlight(line.strip())
         return output
 
     @requires_admin