The security issues from the AVSEC side
As I mentioned in my first comment, I feel well qualified to comment on the security issues, after my years spent as a detective inspector and, subsequently, an AVSEC specialist.
The furore surrounding the confirmed use of at least two stolen passports by PAX on MH370 raises many issues but doesn't strongly indicate terrorism or foul-play in this specific case.
There is a highly variable standard of screening indifferent countries, even different airports in the same country. There is no standardised training, globally. There is no global standard for passport design and security features. There is no global agreement over the use of the Interpol stolen passport database. There is no requirement for countries to notify Interpol about stolen passports. Most countries pay only cursory attention to passports when PAX are leaving a country. Airlines have no access to any stolen passport databases and only check for the appropriate visas at check-in.
By now, you should be getting the picture: there are more holes in the security net than a sieve. However, there are a number of factors that should have set alarm bells ringing. Tickets paid in cash, tickets bought by a third party, a long-way-round itinerary, one-way tickets, etc., are all classic indicators that something dodgy is going on and should be investigated before the two PAX are allowed to board that flight.
However, all these signs were missed. Why? I think the lack of good, old-fashioned paper tickets, which contained all the information needed to join the dots on a single coupon, is partly to blame. That being said, these PAX did have a paper coupon with the info on it and still the warning signs were missed. I suspect that check-in staff, many of whom are now contracted from third party vendors by airlines, do not have the requisite training to spot the warning signs.
As I mentioned above, immigration staff often do not have access to the right information and often pay no attention to other travel documentation aside from the passer, so they miss the warning signs as well. Security staff are concerned only with physical security not documentation. Then, of course, we have to remember that even well-trained humans make mistakes.
But the bottom line is that it is far, far too easy to evade detection when travelling with false or stolen travel documents. Not all those who do it are terrorists, but they certainly are criminals and up to no good.
Does this help us solve the riddle of MH370? No, right now it's a distraction from the main aim, which is to find the aircraft. Only then can the proper investigation begin. It will have to work backwards. Finding out the cause of (almost certain) crash and, if foul play was involved, working backwards to try and find out who was involved.