Three Ways to Attack

 
 
By Peter-Michael Ziegler  |  Posted 2002-06-03 Print this article Print
 
 
 
 
 
 
 


There is thus only one way at present to determine how vigorously the current biometric security systems are able to resist attempts at overcoming them: test-it-, assail-it-, and outfox-it-yourself. Attempts undertaken to breach the systems can roughly be assigned to three different scenarios:
  • The first approach relies on tricking the biometrics system with the aid of artificially created data whilst making use of the regular sensor technology of the system; a precondition for this approach being spy-work that gets hold of more or less easily obtainable biometric features such as an image of a face or a fingerprint. After developing the appropriate photograph(s) and/or creating the artificial fingerprint(s) required, these copies of features can then be used to attempt to obtain authentication. The reactivating of traces of fat on a fingerprint scanner- of so-called latent images - also belongs to this scenario.
  • The second scenario also entails tricking the biometrics system with artificial data. In this case, however, by playing back to it reference data sets, collected, for instance, with the aid of a sniffer program listening on the USB port, the systems regular sensor system is bypassed. This procedure is commonly called a replay attack. For more on USB sniffers and hardware analyzers consult the Attacking Via the USB Port box.
  • The third approach is made up of attacks that aim at the data base directly. In general this scenario requires that one be in possession of data base administrator rights and have permission to exchange sets of data used as reference sets for recognition purposes. In the event that these data sets have no separate protection of their own the assailant has the opportunity of forging user data with a view to reactivating these at a later date in accordance with his or her designs. In the sensitive area of financial transactions this could turn out to be a ticking time bomb. Vide the hypothetical case of a former bank employee who years after leaving his firm decides to bring back to life the at one time surreptitiously created data set Mr. Millers eleventh finger with the intention of generously taking care of his retirement needs.
In our attempts at outfoxing the protective programs and devices we have concentrated on the first method: direct attempts at deceiving the systems with the aid of obvious procedures (such as the reactivation of latent images) and obvious feature forgeries (photographs, videos, silicon fingerprints). After already obtaining astonishing results by means of this approach, we conducted exemplary tests only on whether it was possible to extract biometrically-relevant data by eavesdropping on the communication via the USB port between the computer and the sensor.


 
 
 
 
 
 
 
 
 
 
 

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