Proper Wiring in Attic

When trouble shooting a roof leak in the attic I came across some exposed wiring i.e. 3 wire 14 AWG Romex connected with wire nuts. I have two lights that are controlled by one switch for my back porch. . After tracing each it looks like the second light was run off the lead to the first light...obviously aftermarket. The first light is mounted to an eave with no access from above and the switch is on an outside wall so I understand why the previous owner elected to tap into the line where he did. I know the right answer would have been to run the lights in series from #1 to #2 or in parallel from the switch but...

Can I just add a juntion box to cover the exposed wiring and mount it to a ceiling joist to bring it up to code or do I need to rewire the whole thing?

Corpus Christi Texas if it matters.

Thanks,
Boyd

All junctions need to be made in a proper box or fixture. The box can't be hidden inside of a wall, but I don't think loose insulation would be an issue. Terminology can get picky when dealing with electricity...series isn't what you meant. All typical lighting fixtures are done in parallel. Now, whether it ends up being done as a daisy chain or a star configuration doesn't really matter - whatever layout works for your situation. The only issue that may apply is the temperature rating of the wiring since it is being used in the attic. Not sure what the code is for that. Most stuff is probably okay.

Boxes need to be accessible, which means they can be covered by batt or loose insulation. A few inspectors have told me that they consider accessible to mean it takes nothing more than your hands and a screwdriver to get the box open. Jadnashua is right about the junction... it needs to be in a box with a blank cover plate. HTH.