#33C3- Changing travelers flight bookings is really too easy for hackers

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Changing travelers flight bookings is too easy. Absolutely astounding the Karsten Nohl research on the insecurity of traveler flight information.

The current travel booking systems is deeply insecure, it lacks of cyber security by design and the notorious hackers Karsten Nohl and Nemanja Nikodijevic have demonstrated it at the 33rd Chaos Communications Congress held in Hamburg last week (“Where in the World Is Carmen Sandiego?”).

The experts explained that it is quite easy to modify any passenger’s reservation, cancel their flight bookings, and even use the refunds to book tickets for themselves.

The security duo has conducted for several months a research on security employed by the Global Distribution Systems (GDSs) that are used by various actors in the travel industry, including airlines, travel agencies, hotels and car rental companies.

Below the video of the presentation held during the 33rd Chaos Communications Congress.

GDSs are enormous archives containing all information about travel bookings, they include so-called Passenger Name Records (PNRs), records include information such as traveler’s name, itinerary, travel dates, ticket details, phone number, email, passport information, credit card numbers, seat numbers and baggage information. Travel data is precious for scammers and phishers that could use them to launch targeted attacks and organize complex frauds.

As explained by the experts the most important GDS operators in the world are Sabre, Travelport, and Amadeus. The disconcerting discovery made by the researcher is that it is possible to add or modify any travel data by accessing the system with a last name and a six-character booking code.

We have to think GDSs as systems accessible from everywhere, access points could be airline websites, travel agencies, and also third-party websites like CheckMyTrip. Every time a travel includes flights with different airlines the booking can be modified through the websites of any of the airlines that operate the trip.

Attackers could cancel a flight, and if the booking allows the change crooks could use the credit given by the airline to book a new ticket.

Unfortunately, the level of protection for the PNR is very poor, the booking code is easy to obtain, it is printed on luggage tags and is also embedded in the QR codes printed on the tickets.

Passengers use to throw away old Boarding Pass even when the overall travel isn’t yet completed, or even worse, they post on social networks the pictures of the tickets.

We explained in the past that Boarding Pass contains personal information that could be exploited by hackers.

The popular investigator Brian Krebs published an interesting post on the topic explaining that a Boarding Pass Barcode contains a lot of data.


flight bookings boarding pass barcode


Experts highlighted that there is no logging implemented in the GDSs, this means that is impossible to discriminate the accesses.

“In the short term, at the very least we should expect websites that give access to travelers’ personal information to have the bare minimum of web security, and this includes at the very least some rate limiting,” the researcher said. “And until passwords and other security measures become common, I think we have a right to know who accesses our records and there must be some accountability, especially knowing how insecure these systems are today.” explained Nohl.

Karsten Nohl and Nemanja Nikodijevic explained that many airline and trip checking websites don’t limit the number of bad codes users can enter before they’re blocked, opening the door to brute force code-guessing attacks.

The duo demonstrated that it is a question of minutes to find matching booking codes for popular last names by using automated methods. Working with GDSs brute force code-guessing attacks are very easy because the systems use only uppercase letters. The researchers explained that one of GDS analyzed doesn’t use 1 and 0 to avoid confusion with the letters I and O, two other GDSs increase the codes sequentially making easier for an attacker to guess the code withing a sequence.

“The travel agencies have their own master logins into the GDSs and these accounts have very weak passwords. In one case the password was WS, which stands for web service, followed by the date when the login was created in DDMMYY format. This can easily be brute-forced and unfortunately it was one of the most complex travel agency passwords the researchers observed.” reported CSOonline.