Block ciphers are typically resistant to direct attacks, such as an exhaustive key search or cryptanalysis, all of which require too many resources to achieve an efficient attack. Many block ciphers are examined for their resistance to less direct attacks that target a given implementation. Of these attacks, fault attacks are amongst the most effective at retrieving information on secret key, and require specific countermeasures to be included in an implementation. In this paper we describe a simple platform for the study of fault injection and analysis in the context of fault attacks block ciphers based on a Feistel structure (e.g. DES). We show that an attacker who can successfully inject faults into a block cipher can reduce the complexity of an attack to derive the secret key. We also present a novel version of the attack than can be applied to Triple-DES by independently injecting faults in the second and third instantiations of DES involved in a Triple-DES computation.